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Mrs. Kalafsky - AP Biology
Ecology Summer Assignment 2013
Welcome to AP Biology!
In an effort to be prepared for the AP Biology exam, we have a tremendous amount of
work ahead of us before May 12, 2014! I hope you are all up for the challenge! To start
us off I have attached your 2014 Summer Assignment.
Books:
 It is imperative that you order your text with Mastering Biology immediately. Use
of the text is required for the summer assignment. Lack of a text will not be
accepted as an excuse for a missing portion of the summer assignment.
 As a reminder, these are the two texts you were given information on a few weeks
ago:
Campbell Biology, 9e AP* Student Edition (HS Binding) + MasteringBiology
with Pearson eText (6-year access)
isbn10: 0131375040
isbn13: 9780131375048
AP* Test Prep Workbook for Campbell Biology—Revised for New Curriculum
price: $14.97
isbn10: 0321856635
isbn13: 9780321856630
Other Essential Information:
 You may reach me all summer via my email address
(gaetanakalafsky@popejohn.org) or cell (201-213-5727).
 Please do not hesitate to ask questions. Better to ask up front then to be
disappointed in your grades.
 Do not wait until the last minute to submit your assignments. I have set a time
deadline of 11:59 pm for each assignment. This will be 11:59 pm as set by Pope
John’s email system.
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PART 1: Complete Before June 21, 2013
Email the following information to me. Be sure to email it from an account that you
WILL check throughout the summer:
1.
2.
3.
4.
Name
Grade (2013 – 2014)
Why did you register to take AP Biology?
What are your personal strengths when it comes to learning new material? How
do you learn best?
5. What causes you to struggle in a course?
6. What is the most effective way for you to prepare for a test?
7. At this time, what do you plan on majoring in when you get to college?
PART 2: Due June 28, 2013
Register for the Mastering Biology site using the access code purchased with your text.
1.
2.
3.
4.
5.
6.
7.
8.
Register at www.pearsonschool.com/access
Enter the first 6 letters of your code (purchased with your text)
Click on Covered Titles to Select Discipline and Title
Click on Science
Select Campbell, Biology 9e AP* Edition
Choose Student Registration
Accept - Pearson License Agreement
Access Information
 Create your username & password
* Enter your complete access code
9. Account information – complete this section with your name & school
information
10. A Confirmation and Summary will be visible on the screen and emailed to you.
Register for your specific class within Mastering Biology.
1. Log in to Mastering Biology.
2. Click YES to the question Did you receive a course ID from your instructor.
3. Enter the following Course ID: KALAFSKYAPBIOLOGY20132014 and click
Continue.
4. Skip the step that asks you to enter your student ID.
5. You should now be on our specific Mastering Biology Course home page.
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Learn to use Mastering Biology.
1. On the Assignments tab, complete the Introduction to Mastering Biology
assignment.
2. This assignment must be completed prior to June 28, 2012 at 11:59 pm.
Note: If you have any difficulty accessing Mastering Biology, I must be notified before
June 28, 2013!
PART 3: Due August 16, 2013 (by 11:59 pm)
AP Biology must cover the topic of Ecology. Since emphasis is placed on understanding
concepts, not plain memorizing of facts, you can read the chapters on Ecology as a
summer assignment. Ecology is the scientific study of the interactions between organisms
and the environment. Because of its great scope, ecology is an enormously complex and
also an exciting area of Biology.
For each chapter, I have provided additional essats that contain relevant ideas or data on
the chapter content. Read the essays that pertain to the chapter, then read the chapter
and answer the questions.
Question for each chapter should be answered after you have read the article and the
chapter. Follow the chapters in order in order to acquire a better understanding of the
topics covered in each section. After completing the written questions for each chapter,
complete the masteringbiology quiz for the completed chapter.
After successful completion of all of the chapters, questions, and mastering biology
quizzes, you will be required to complete an free response question (FRQ) related to the
topics you have just learned. The FRQ is located immediately in this document,
immediately after the chapter questions.
In summary:
Read Chapters 51 – 56 and the corresponding essays (located in this packet).
 Complete the attached assignments for Chapters 51 – 56.
o Scanned and emailed or mailed to my home by 11:59 pm 8/16/13
 Complete the chapter quiz for each chapter (51 – 56). To do this you must log in
to the Mastering Biology web site.
o To be completed by 8/16/13 at 11:59 pm.
 Complete the FRQ (found after the chapter questions)
o
Emailed to me by 11:59 pm 8/16/13
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Chapter 51: Animal Behavior
Essay - Mating Systems in Sexual Animals
1. How is behavior defined?
2. What is ethology?
3. What is the difference between proximate and ultimate causation?
4. Using red-crowned cranes, provide an example of a proximate causation question
and an example of an ultimate causation question?
5. What is a fixed action pattern (FAP)? Provide one example not presented in the
text.
6. What is a sign stimulus? Give at least 3 examples of sign stimuli (2 of the examples
must not be presented in the text.
7. Nicholas Tinbergen’s work with the stickleback fish is a classic study. Explain
what he found. Use the terms fixed action pattern and sign stimulus in your
response.
8. Define the both kinesis and taxis and provide one example of each term not
presented in the text.
9. Explain what is meant by circadian clock and circadian rhythm. Identify two
behaviors, either plant or animal, that demonstrates a circadian rhythm. (You may
need to refer to other chapters in the text for examples).
10. Explain two navigational strategies used by birds to migrate.
11. Animals communicate in various ways. Discuss at least three specific examples of
animal communication using different organisms.
12. Note Figure 51.4 that shows fruit fly courtship behavior. Identify two other modes
of communication used by the fruit fly?
13. Karl von Frisch studied European honeybees. What are the two types of dances
that a returning worker bee does, and what information does each dance convey?
Use a labeled sketch to describe each dance.
14. What are pheromones? Give three specific types of information that can be
transmitted through pheromones.
15. Based on cross-fostering and human twin studies, what are the two factors that
contribute significantly to behavior?
16. What is the difference between innate and learned behavior? Give an example of
each.
17. What is meant by fitness? How can habituation increase fitness?
18. Describe the process of imprinting, and explain what is meant by sensitive or
critical period.
19. Describe the classic study of parental imprinting done by Konrad Lorenz.
20. What occurs in spatial learning?
21. What are two types of associative learning? Which type did Ivan Pavlov use to
get a dog to salivate at the sound of a bell?
22. What occurs in operant conditioning?
23. What is cognition? Give three examples of cognition in animal species; include at
least one bird behavior.
24. Many bird songs are learned during a critical period. What will happen if a whitecrowned sparrow does not hear the song of its species during this time?
25. What is foraging behavior?
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26. What is proposed by the optimal foraging theory? Explain it in terms of cost and
benefit, and cite two examples from your text.
27. To demonstrate that you understand the principle of optimal foraging, describe a
food source that you would not be likely to exploit.
28. Explain each of the following mating systems and provide one example of a
species that uses each system.
a. Promiscuity
b. Monogamy
c. Polygamy
d. Polygyny
e. Polyandry
29. What is sexual selection? (See Chapter 23)
30. There are two types of sexual selection. Explain each of them.
a. Intersexual selection
b. Intrasexual selection
31. What is agonistic behavior? Give one example of this behavior that is not in your
book.
32. What is altruism?
33. Explain the evolutionary advantage to a population of having members who
exhibit altruistic behavior.
34. Altruism may reduce the fitness of an individual—for example, by making that
individual more obvious to a predator. Explain this behavior using the concept of
inclusive fitness.
35. Explain the logic behind the comment that a person would lay down his life for
two brothers or eight cousins.
36. Contrast kin selection and reciprocal altruism. Do not simply give a definition.
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Chapter 52: An Introduction to Ecology and the Biosphere
Essay – Global Warming
1. What is ecology?
2. What is a biome?
3. Figure 52.20 shows a climograph for some major biomes in North America. What
two abiotic factors shown here are most important in determining the distribution
of the biome?
4.Describe each major terrestrial biome as to rainfall, temperature, location, and
representative flora and fauna.
Biome
Rainfall
Temperature Location
Flora (at
least 2)
Fauna (at
least 2)
Tropical
Rainforest
Desert
Savanna
Chaparral
Temperate
grassland
Northern
coniferous
forest/Taiga
Temperate
broadleaf
forest
Tundra
5. What is the largest marine biome, and how much of Earth’s surface does it cover?
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6. As you read this section and study Figure 52.13, you will encounter a number of
new terms. Distinguish between each of the following pairs of terms:
a. photic/aphotic
b.benthic/pelagic
c. oligotrophic/eutrophic
d.littoral zone/limnetic zone
e. zooplankton/phytoplankton
f. neritic/abyssal
7. Complete the following chart of the aquatic biomes.
Biome
Lakes
Wetlands
Streams and
rivers
Estuaries
Intertidals
Ocean Pelagic
Description
Autotrophs
(at least 2)
Heterotrophs
(at least 2)
Negative
Human
Impact
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Chapter 53: Population Ecology
Essay – Population Ecology, Tales of Nightmare Numbers
1. Draw type I, II, and III survivorship curves on a graph with labeled axes. Explain
why the growth rate of species with a type I survivorship curve depends primarily
on fertility rates. Explain whythe growth rate of species with a type III
survivorship curve is extremely sensitive to changes inadult survivorship.
2. Make a rough sketch of the age distribution in developing versus developed
countries, and explain the significance of the differences.
3. Consider 2 rivers: One is spring fed and is constant in water volume and
temperature year- round; the other drains a desert landscape andfloods and dries
out at unpredictable intervals. Which is more likely to support many species of
iteroparous animals? Why?
4. Explain why a constant rate of increase (rmax) for a population produces a growth
graph that is J- shaped rather than a straight line.
5. Offer a hypothesis to explain why humans have undergone near-exponential
growthfor over 500 years. Why can’t exponential growth continue indefinitely?
Give 2 examples of density- dependent factors that influence population growth in
natural populations.
6. Where is exponential growth by a plant population more likely- on a newly
formed volcanic island or in a mature, undisturbed rain forest? Why?
7. How does the prediction of the exponential model of population growth differ
from that of the logistic model?
8. What is carrying capacity? Is it a property of a habitat or of a population?
9. What is time lag?
10. How have humans sidestepped the controls that regulate populations of other
organisms?
11. How does the age structure of a population influence its future population
growth?
12. Explain why a population that fits the logistic growth model increases more
rapidly at intermediate size than at relatively small or large sizes.
13. Identify three density-dependent factors that limit population size, and explain
how each exerts negative feedback.
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Chapter 54: Community Ecology
Essay – Community Interactions: No Pigeon is an Island
1.
2.
3.
4.
Why are there limits on the food chain length?
Compare a dominant species with a keystone species – give an example of each.
How do keystone species influence species richness in communities?
What are the differences between cryptic coloration, aposematic coloration, and
mimicry? Explain the differences.
5. Compare bottom-up and top-down controls on biological communities and their
organization.
6. What is disturbance and give an example?
7. To investigate the structure and function of ecosystems, ecologists may construct
a microcosm using organisms and materials from the ecosystem. Properly
constructed, these model systems should be self-sustaining. If you remove the
primary producers from the microcosm, would you predict that your model would
continue to be self-sustaining? Explain.
8. If you remove the decomposers and detritivores, would the microcosm be selfsustaining? Explain.
9. Species interactions affect the distribution and abundance of populations.
Summarize experimental evidence that population size for snowshoe hares
depends on both predation rates by lynx and competition for food among hares.
10. Using your knowledge of ecosystem structure and function, compare the trophic
structure of a desert to that of a temperate hardwood forest. Include the relative
number (not exact) of organisms and energy availability for the different trophic
levels.
11. What is the difference between primary succession and secondary succession?
12. How does the essay, No Pigeon Is An Island, explain the information about
community interactions in this chapter?
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Chapter 55 (Ecosystems and Restoration Ecology) and Chapter 56 (Conservation
Biology and Global Change)
Essay – Phosphate Pollution, Acid Rain, and the Ozone Hole: Hope for the
Ecosystem Recovery
Essay – Exotic and Endangered Species
1. Why is the transfer of energy in an ecosystem referred to as energy flow, not
energy cycling?
2. How are detritivores essential to sustaining ecosystems?
3. Why is only a small portion of the solar energy that strikes Earth’s atmosphere
stored by primary producers?
4. What is the difference between gross primary productivity and net primary
productivity?
5. What environmental factors influence rates of primary productivity in terrestrial
and aquatic ecosystems?
6. Why is an ecosystem’s net primary production lower than its gross primary
production?
7. On a global scale, herbivores consume only about17% of net primary production
be terrestrial plants, yet most plant biomass is eventually consumed. Explain.
8. Why is energy lost from a ecosystem at every transfer from one trophic level to
the trophic level above it?
9. Marguerite has a vegetable garden in Maine. Eduardo has one in Florida. What
are some of the variables that influence primary production in each place?
10. Look around you and name all of the objects, natural or manufactured, that might
be contributing to amplification of the greenhouseeffect.
11. Why does deforestation of a watershed increase the concentration of nitrates in
streams draining the watershed?
12. Draw a SIMPLE diagram that shows one possible path for an atom or molecule of
that chemical from abiotic to biotic reservoirs andback for each of the 4
biogeochemical cycles.
13. How can the addition of excess nutrients to a lake threaten its fish population?
14. In the face of biological magnification of toxins, is it healthier to feed at a lower
or higher trophic level? Explain
15. Suppose that herbivores were removed from a temperate deciduous forest
ecosystem. Predict what would happen to the rate of nitrogen cycling. Explain the
logic behind your prediction.
16. What is Earth’s main reservoir for phosphorus, and why is it recycled at such a
slow rate from that reservoir?
17. In 1997, nonnative and invasive Asian swamp eels were collected in Florida for
the first time at two sites near Tampa and Miami. These fish are extremely
adaptable to a wide range of freshwater habitats, from wetlands to streams and
ponds. They are predators that feed on worms, insects, crayfish, frogs, and other
fishes, including bluegill and bass. Swamp eels have the ability to gulp air, which
allows them to survive in only a few inches of water and to move over land to a
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nearby body of water. Scientists are tracking their movements and increasing
numbers in the Southeast. In one pond, several species of fish have been
completely eliminated. Based on your understanding of the pond ecosystem,
predict the effect of introducing swamp eels on the following components of the
pond.
Bluegill:
Bass:
Pond Life:
18. Using your knowledge of ecosystem structure and function, propose a plan of
action for eliminating the swamp eels (question 17) from the pond before they
eliminate the other organisms. You cannot use toxins, since the local anglers fish
in this pond.
19. In what ways would humans benefit by preserving biodiversity?
20. Describe the 4 main threats to biodiversity and how each one damages diversity.
21. Why does the reduced genetic diversity of small populations make them more
vulnerable to extinction?
22. How do naturally occurring organisms provide humans with ecosystem services?
23. What are the consequences of the overexploitation of fish populations?
24. How do extinction rates today compare with the background extinction rate
evident in the fossil record?
25. Would a single large nature preserve or several small preserves experience greater
edge effects?
26. Why is a population’s effective size (Ne) almost always smaller than its total size
(N)?
27. What are the goals of restoration ecology?
28. How do bioremediation and biological augmentation differ?
29. What is meant by the term sustainable development?
30. What are the lessons that can be learned from the essays – use information from
the chapter to explain your answer.
ECOLOGY FRQ
After reading the ecology chapters 51-56 and completing the question listed above,
complete the following FRQ. This is a graded essay.
Your Answer must be in essay form. Outline form is NOT acceptable. Labeled diagrams
may be used to supplement discussion, but in no case will a diagram alone suffice. It is
important that you read the question carefully before you begin to write.
Your answer MUST be an original work. DO NOT copy from a friend or take
information directly from the web. Although your answer may differ from others in the
class, it does not mean it is wrong. As long as you answer logically and reasonably
provide correct information you will be given credit.
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These answers do not have to be lengthy. You can answer each part in one paragraph. I
am grading on correct information. The food chain can be depicted using arrows between
the organisms.
FRQ
1.
a) Living organisms play an important role in the recycling of many elements within
an ecosystem. Discuss how various types of organisms and their biochemical
reactions contribute to the recycling of either carbon or nitrogen in an ecosystem.
Include in your answer one way in which human activity has an impact on the
nutrient cycle you have chosen.
b) The survival of organisms depends on regulatory mechanisms at various
levels.Explain how the density of a population is regulated.
c) Compared with other terrestrial biomes, deserts have extremely low productivity.
Discuss how temperature, soil composition, and annual precipitation limit
productivity in deserts.
d) Describe a four-organism food chain that might characterize a desert community,
and identify the trophic level of each organism.
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ESSAYS FOR AP BIOLOGY SUMMER ASSIGNMENT
Essay – Chapter 51
Mating Systems in Sexual Animals
One of the most fascinating aspects of human life is how we choose our mates. Animals
also choose their mates, sometimes with a great deal of care. Mating systems are
important to understand because they reflect the result of natural selection on mate
choice, and ultimately on strategies for maximizing individual reproductive success.
A mating system describes how males and females pair when choosing a mate. Males and
females differ greatly in the investment each makes to reproduce, and may therefore
approach mating with differing strategies. To study these differences, scientists observe
mating systems and describe how males and females come together. When choosing
mates, animals evolve species-typical strategies for maximizing their reproductive
success — this results in considerable diversity among animal species in their mating
patterns.
In this article we first discuss why sexual reproduction exists, and how differences
between males and females affect mating systems. We move on to consider the evolution
of mate choice, and then we describe the types of mating systems found in animals.
The Evolution of Sex
Asexually reproducing animals pass on all of their chromosomes, and consequently all
copies of each gene, to their offspring. In contrast, due to meiosis, diploid sexually
reproducing animals have two copies of each chromosome but only pass one copy of
each chromosome on to an egg or sperm cell. This means that a sexually reproducing
diploid animal only passes half of its total genes on to its offspring. Despite the cost of
losing half of the potential passage of genes to the next generation, sexual reproduction is
much more common than asexual reproduction among animals because it provides
several evolutionary advantages. The major advantage of sexual reproduction comes
from genetic recombination. Genetic recombination allows an organism's offspring to
be genetically diverse. Sexual reproduction increases the chances of acquiring favorable
mutations and is unlikely to propagate deleterious ones. Genetic diversity within a group
of offspring is advantageous as the local environment changes. This idea becomes clear
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when we examine organisms that can reproduce both sexually and asexually. Aphids, for
example, will favor asexual reproduction when their environment is stable. When the
environment is going to turn cold, most species of aphids reproduce sexually, because
sexual reproduction produces eggs that are freeze tolerant and can diapause during the
winter (Simon et al. 2002). Genetic diversity may also lead to evolved defenses against
parasites and disease. The mud snail, Potamopyrgus antipodarum, is host to several
trematode parasites. Sexual individuals of this species are more common in areas where
risk of trematode infection is high. In areas where the risk of infection is low, asexual
individuals have displaced sexual ones (King et al. 2009). This suggests that the genetic
diversity acquired from sexual reproduction is necessary for this species to defend against
parasites, as asexual individuals may not easily survive in areas where parasites are high.
Sexual reproduction often involves evolutionary differentiation of males and females.
Females typically produce significantly fewer gametes (eggs) than males and invest
heavily in each one. On the other hand, males produce many gametes (sperm) and invest
little into each one. These strong differences in gamete investment between the sexes
leads to reproductive strategies between the sexes that, in some cases, conflict. Females
may spend more care than males selecting a mate due to the high cost of their gametes.
Figure 1: A male bighorn sheep.
Variance in Mating Success and Bateman's Principle
A key element of the study of mating systems is understanding how many mates an
animal has in its lifetime. Bateman's principle helps to make predictions about mating
success and number of mates. Bateman's principle postulates that variance among
females in mating success is low, whereas variance among males in mating success is
high. This stems from the fact that one mating in females should be enough to fertilize all
their eggs whereas in males reproductive success is based on the number of times they
have mated. In other words, nearly all females in a population mate and have offspring,
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but relatively few males mate successfully (Figure 2). Those males that do mate tend to
mate with many females-thus a few males have very high reproductive output, but many
males have little or no reproductive output (Bateman 1948). This leads to the prediction
that sexual selection should act more strongly on males, leading to greater elaboration of
behavior and structures used in attracting mates in males than in females.
Figure 2: Bateman’s principle.
These figures illustrate Bateman’s principle — after one mating, female mating
frequency increases and relative fitness remains constant, as the sperm from one mating
is adequate to fertilize all the female’s eggs. In males, as mating frequency increases
relative fitness also increases proportionally.
Criticisms of Bateman's theory focus on the generality of the predictions. Contrary to the
predictions of Bateman's principle, there are several possible advantages to female
multiple matings. The female cichlid fish Pseudotropheus spiliopterus mates with any
male they meet because they have a high risk of getting predated and a small population.
This often leads to multiple matings by a single female (Kellogg et al.1998). Mating with
any male that is seen ensures that these cichlids have a chance at producing offspring.
The female Malawi blue cichlid has a high population but still participates in multiple
matings. In this case multiple matings occur to avoid inbreeding and increase genetic
diversity among the offspring (Kellogg et al. 1998). Additionally, multiple matings by
females may increase the likelihood that they will find a compatible mate, one that is not
sterile, or even help prevent infanticide.
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Female Mate Choice
Mate choice is also a key element of mating systems. In most species, females are
choosier when picking a mate than males. A significant reason for this is the higher
investment females make in each gamete than males. Females may prefer certain males
for a variety of reasons, including "good genes", meaning that the male has attributes
which predict better survivorship of the offspring, good potential parenting by the male,
or possession of resources by the male that will support the offspring during their growth
and development.
Additionally, in most species, females are more likely to provide parental care. Females
that carefully select their mates are at a lower risk of losing their reproductive investment.
Males may be under strong selection for certain traits that are favored by females. Most
females look at these traits as indicators of their partner's fitness. Selection favors females
that choose males that enhance the likelihood of her offspring's success. Males with more
elaborate ornamentation, or that are more colorful, can be displaying a good indicator of
value as a mate, and may win the chance to mate with a particular female. (Figure 3).
Although mating is important, it can be a costly event — females are predicted to be
choosier about selecting their mates than males because of risks during mating, such as
aggression or disease transmission, which may negatively impact the female's
reproductive output.
Figure 3: Eyespots from peacock tail feathers.
Elaborate ornamentation usually evolves in intrasexual selection and is used in mate
choice.
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Male Mate Choice
The importance of male mate choice is controversial. Older theory predicts that male
mate choice should be less common in animals. However it plays an important role in
many mating systems, and the cost of mating for males may have been underestimated in
earlier studies. Male mate choice occurs most often when males are substantially
involved in caring for their offspring, or when there is great variation in the quality of the
females as mates within a population. If males are choosy about their mate, then over
time females may evolve ornamentation or coloration that is subject to sexual selection.
Types of Mating Systems
Monogamy
Social monogamy is the behavioral pairing of a single male with a single female. It is
most common in birds and rare in other animals (Figure 4). Theoretically, individuals in
monogamous pairs will both contribute to the defense and parental care of offspring.
Choosing an inappropriate mate could have a high fitness cost (see the sections above for
more on mate choice). Because the costs of poor mate choice in monogamous species can
be so high, in some instances organisms engage in strategies of either serial monogamy
or extra-pair copulations. Extra-pair copulations are very common in birds (Petrie et al.
1998, Stutchberry 1998). Monogamy reduces the potential for genetic variation among a
female's offspring. By mating with more than one male over the course of her lifetime, a
female gains higher genetic variation among her offspring. The benefits of monogamy,
which are shared parental care and territorial resources, are maintained by having only
one mate at a time, or by concealing extra-pair partnerships.
Figure 4: Blue-footed boobies.
Many bird species, such as these blue-footed boobies are monogamous.
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Polygyny
Polygyny is the association of one male with multiple females. This mating system is
found in a few birds and insects, but is most common in mammals. Polygyny is a strategy
used by males to increase their reproductive fitness.
Resource Defense Polygyny
In resource defense polygyny, groups of females are attracted to a resource — males
then compete for territorial possession of the resource, and, by extension, mating priority
with females at the resource (Beletsky 1994). Thus, individual males form territories
centered on resources needed for successful mating (McCracken 1981).
Harems
Another common type of polygyny is membership in a harem, a defended group of
females associated with one male. Females may initially associate in a harem for group
defense, or they may be herded together by a male. Males compete for control of the
groups. Harems typically exhibit a dominance hierarchy among the females in the group.
Leks
A lek is an aggregation of males that are each seeking to attract a mate. Within a lek,
males typically perform sexual displays. Unlike most other mating systems, leks are not
associated with resources. Aggregations of males may be near particularly attractive
females or in areas where females are likely to travel (Lank et al. 1995, Aspbury &
Gibson 2004). It is thought that males form leks because they attract more females than
do isolated males. Attracting more females is a strategy used by males to help increase
their reproductive success.
Polyandry
Polyandry is a group with one female and many males. Polyandry is a reproductive
strategy that helps a female ensure reproductive success by providing her with multiple
mating options.
Resource Defense Polyandry
In the Spotted Sandpiper, females control resources, which in turn controls male mating
associations (Oring et al. 1994).
Cooperative Polyandry
The Galapagos hawk exhibits cooperative polyandry. In this case all males in the group
copulate with the female and all participate in brood provisioning (Fabborg et al. 1995).
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Polygynandry
Some mating systems have looser male-female bonds within groups. In polygynandrous
groups, multiple females and males mate with each other, and males may care for the
broods of several females. Chimpanzees and bonobos rely on this strategy — it allows
groups of males and females to live together and spend less time being concerned with
mate competition. Polygynandry may be advantageous from the female's perspective
because it causes paternity confusion, which decreases infanticide and allows her to have
multiple males care for her brood (Hrdy 1981, 2000).
Promiscuity
In promiscuity there are no pair bonds, and males and females, although sometimes
choosy, often seem to mate randomly. As it is typically more advantageous for one or
both sexes to pick their mate, promiscuity may occur in species for which the
environment is unpredictable (Birkhead 2000, Burton 2002).
Sperm Competition
Although sperm competition is not a type of mating system per se, it is a form of malemale competition that plays an important role in mating systems. If more than one male
mates with a female in a short time period, competition can occur after the males have
released their sperm (Fisher & Hoekstra 2010). In other words, once a male has released
sperm, its sperm must be the first to reach an egg. This is often apparent in animals that
use external fertilization. In aquatic animals that release their gametes into the water,
animals that release the largest amount of sperm, and sperm that are highly capable of
swimming, are likely to produce the most offspring (Stoltz & Neff 2006). Animals with
internal fertilization also experience sperm competition. Several mechanisms have
evolved to facilitate a male's reproductive success with females that have multiple mates.
For example, in one species of damselfly, males physically remove any sperm present
from the female before it mates (Waage 1979). Sperm competition adds to the difficulty
of obtaining a successful reproductive event by males.
Conclusions
To transfer their genes to the next generation successfully, animals need to choose a
suitable mate. Failure to do so leads to low or no reproductive success — that is, poor
fitness. But reproductive success can also hinge on the number of mates, and on social
interactions that extend beyond mating. By classifying social interactions, scientists have
been able to identify different types of mating systems, such as monogamy and polygyny.
The mating systems described in this article represent a variety of strategies to achieve
reproductive success. The diversity of mating systems in animals is a fascinating example
of the incredible variety of solutions that a complex evolutionary problem can yield.
Essay – Chapter 52
Global Warming
Kalafsky 20
As the general public and scientists alike become more aware of the suggested patterns
and problems of global climate change many begin to realize that not just humans will be
affected in the future. We are but one of many species that will be forced to adapt to
changing conditions. Those who are unable or fail to adapt will be eliminated by others
who can. It is important to understand that regional changes are much more accurate and
useful to examine rather than trends on a global scale. Also, when global trends are
measurable the changes have already affected the regional elements in huge ways; there
exists no reaction time. It is also not realistic to apply these regional changes to all
species within its limits. Different species will be affected differently. Consequently, we
have chosen birds to narrow our study on how climate change affects species distribution.
Birds are excellent indicators of change in spatial distribution and changes have been
well documented for birds. We first examined the different problems and issues
surrounding global climate change. We then discussed the different theories seen behind
the alteration of species distribution due to climate change, and why this is important. We
then looked at how different species distributions have altered in general. We
concentrated on the change in distribution of birds (as they are a good example of species
indicators) including factors as abundance and location, testing if they have changed
within the recent past and whether or not these results can be attributed to climate
changes.
In recent history the world climate has seen significant changes. These changes are not
necessarily uncommon as compared with changes of the past, but as far as we can tell the
rate and nature of the changes appear to be abnormal. Global climate change includes the
theory of global warming or a rise of temperature due to the increase of greenhouse gases
in the atmosphere. Scientists have suggested that the earth’s average temperature has
increased by as much as 0.6°C (Walther et al., 2002). The estimates on this figure vary
and it is projected to rise another 1-3.5°C in the next century (Hughes, 2000). While this
might not seem like much, the effects of a small temperature increase can be impressive.
The theory behind global warming suggests that increased human activity is putting an
abnormally high amount of greenhouse gases (carbon dioxide, water vapor, methane, and
nitrous oxide) in to the atmosphere. This can happen through the use of fossil fuels for
example, which produce carbon dioxide and methane (Montgomery, 2000). A
greenhouse blanket is formed from these gases, that warms and allows the earth to sustain
life, and it is growing ever thicker. When this happens, the greenhouse gases trap longerwavelength infrared rays that would otherwise be able to be radiated out into space
(Montgomery, 2000). This in turn leads to containing heat within the region between this
blanket and the earth, thus elevating the earth’s temperature (NZCCO). This process is
known as global warming and leads to potential climate changes. Other changes in
precipitation and wind will likely be associated with the temperature changes.
“Associated changes in wind-flow patterns and amounts and distribution of precipitation
will cause differential impacts in different areas, not all of which will be equally
resilient” (Montgomery, 2000). All these changes in climate alter many other aspects of
the natural environment; everything from alterations in ice sheets and glaciers to trended
movements of biomes and species distribution. It can be seen that global warming is a
serious phenomena, potentially affecting sea levels, glaciation, agriculture, ocean cycle,
human health, species spatial distribution, and much more.
Kalafsky 21
Global warming is a complicated process with many causes and effects that are difficult
to predict or control. At the current time it is the general consensus of the scientific
community that global warming and the increase in temperature are largely due to human
action and influence. There exist two types of green house effects; the natural greenhouse
effect and the enhanced greenhouse effect. The natural greenhouse effect prevents the
earth from being frigid and inhospitable. It’s because of these gases that life on this planet
exist, “The natural greenhouse effect causes the mean temperature of the earth’s surface
to be about 33 degrees C warmer than it would be if natural greenhouse gases were not
present (NASA 2).” The enhanced greenhouse effect is the unnatural effect that was
brought on by humans. “It’s the possible raising of the mean temperature of the Earth’s
surface above that occurring due to the natural greenhouse effect (2)”. The greenhouse
gases that are the culprits in the enhanced greenhouse effect are mainly water vapor,
ozone, carbon dioxide, methane, nitrous oxide, and chlorofluorocarbons (CFC’s). Carbon
dioxide along with the other gases have been increasing in the atmosphere over the past
couple centuries, “There has been about a 25 % increase in carbon dioxide in the
atmosphere from 270 or 280 ppm 250 years ago, to approximately 360 ppm today (3).”
These records and recordings of the abundance of carbon fluctuate depending on the
hemisphere you’re in, the season it is, and at what time of day it is. Interestingly enough
the two most abundant gases in the atmosphere, nitrogen and oxygen, have no effect on
the greenhouse warming (unless when combined in the compound of nitrous oxide).
As greenhouse warming continues, there are some processes that seem to counter the
downward spiral of global warming. One example of these processes is in relation to the
carbon cycle. It has been noted that in the global plant community many plants seem to
be taking up more carbon dioxide and storing it in either biomass or soil. It is doing this
in association with the increased carbon dioxide that is present in the atmosphere. Plants
are therefore a sink for the excess carbon dioxide. This process has different implications.
“Air temperatures over the land have increased, resulting in a lengthened growing season
in the northern and mid-latitudes; gradual and slight warming seems to have favored
photosynthesis over respiration-decomposition with far-reaching effects on the global
carbon balance” (NASA FACTS 2). Other processes such as this sink for carbon dioxide
are being studied as to how much of an impact they can have to counter global warming
and their limits on their effectiveness.
An understanding of the current climatic regions and resulting biomes is important for
studying species distributions and changes of distributions. In a traditional system of
physical geography, the world can be broken down into eleven terrestrial biomes based
on vegetation classes. These include equatorial and tropical rain forest, tropical seasonal
forest and scrub, tropical savanna, midlatitude broadleaf and mixed forest, needleleaf
forest and montane forest, temperate rain forest, mediterranean shrubland, midlatitude
grasslands, warm desert and semidesert, cold desert and semidesert, and arctic and alpine
tundra (Christopherson, 2003). These biomes are characterized by the vegetation, soil,
climate including precipitation range, temperature, and water balance. Latitude plays a
big part in determining these biomes as you can tell by some of their names. The most
intense or distinctive biomes are the tropical rain forest, the deserts, and the alpine and
arctic. The tropical rain forest has “consistent year-round daylength (12 hours), high
insolation, average annual temperatures around 25°C (77°F), and plentiful moisture, plant
Kalafsky 22
and animal populations have responded with the most diverse expressions of life on the
planet” (Christopherson, 2003). Average annual rainfall in a rain forest is at least 80
inches and some can have as much as 200 inches per year (Weigle, 1999). There is no dry
season. Tropical rain forests can be found in four main regions: Central and South
America, West and Central Africa, South and Southeast Asia, and Australia (Weigel,
1999). Although the rain forest soils support a vast array of plant life, they are lacking in
nutrients because the plants consume the nutrients so quickly (Weigle, 1999). Common
rain forests plants include bamboo, hibiscus shrubs, orchids, African violets, ferns, and
Spanish mosses (Weigle, 1999). Some of the common rain forest trees are black ebony,
cinchona, mahogany, and mango (Weigle, 1999). Invertebrates are vastly abundant in the
rain forest and include such organisms as termites, army ants, orchid bees, birdwing
butterflies, postman butterflies, and hunting wasps (Weigle, 1999). Reptiles and
amphibians such as frogs, toads, salamanders, snakes, and chameleons are commonly
found here (Weigle, 1999). Mammals of the rain forest include monkeys, shrews, bats,
sloths, gorillas, and jaguars (Weigle, 1999). The rain forest has larger bird populations
than any other biome and includes some of the following: hummingbirds, birds of
paradise, jacamars, eagles, parrots, and junglefowl (Weigle, 1999).
The desert regions are created by descending, drying, and stable air of high-pressure
systems from 8 to 12 months of the year. On average, deserts receive less than 10 inches
of rainfall a year (Weigle, 1999). Here evaporation always exceeds precipitation (Weigle,
1999). Temperatures may reach between 105-110°F during the day in hot deserts
(Weigle, 1999). However, night temperatures can fall to 50°F (Weigle, 1999). Desert
soils are coarse, light colored and high in mineral content (Weigle, 1999). Some deserts
have little soil but rather pebbly rock or desert pavement (Weigle, 1999). Because of
these features, the organisms that live in the desert must be adapted to these conditions.
Consequently for example, many plants have evolved a waxy coating on them to prevent
water loss. Although deserts do not support large numbers of plants and other organisms,
they can support a wide range of organisms (Weigle, 1999). “Cold deserts have hot
summers and cold winters (Weigle, 1999)”. Cold deserts can be found in Kazakhstan,
Uzbekistan, China, Mongolia, and Utah (Weigle, 1999). They can receive precipitation in
the form of snow (Weigle, 1999).
The alpine or arctic regions can have conditions of almost continuous daylight or
continuous darkness for up to two months due to its high latitude. This phenomenon has
to do with the earth’s tilt and overall orbit and the tundra’s location above the Artic
Circle. “Arctic tundra is found across northern Alaska, Canada, and Siberia
(www.cotf.edu)”. Winters here are long and cold while summers are cool and brief.
“Intensely cold continental polar air masses and stable high-pressure anticyclones govern
tundra winters. A growing season of sorts lasts only 60-80 days, and even then frosts can
occur at any time (Christopherson, 2003)”. There are low levels of precipitation, similar
to that of the desert, and dry winds are common (www.cotf.edu). “Vegetation is fragile in
this flat, treeless world; soils are poorly developed periglacial surfaces, which are
underlain by permafrost (Christopherson, 2003)”. The permafrost cannot be penetrated by
roots or water. There are not many animals that live year-round in the tundra. Birds and
mammals such as the artic wolf, brown bear, and muskox, come to live here in the
summer (www.cotf.edu). Mosses, lichens, and grasses can grow in the artic tundra
(www.cotf.edu).
Kalafsky 23
The rest of the biomes are mild or moderate in comparison to those already described,
with conditions of temperature and precipitation and consequently organisms ranging on
a spectrum within these extremes. Grasslands are characterized by having the dominant
plants that are grasses rather than trees or shrubs (Weigle, 1999). Grasslands cover up to
25-30% of the earth and are found primarily in the interior of the continents (Weigle,
1999). They are usually windy and dry for part of the year and are found primarily on flat
or gently rolling hills (Weigle, 1999). Grasslands are considered transition zones between
deserts and forests (Weigle, 1999). The midlatitude broadleaf, or deciduous forest, can be
found in the eastern U.S., central and western Europe, Russia, Japan, and China (Weigle,
1999). Common types of trees here include beech, maple, oak, hickory, ash, and birch
(Weigle, 1999). The soils in a deciduous forest are rich (Weigle, 1999). Needleleaf, or
coniferous forests often have acidic soils due to the high acid content of the needles
(Weigle, 1999). “More than 50 percent of the world’s coniferous forests are found in
Asia, primarily in Siberia, China, Korea, and Japan, and on the slopes of the Himalaya
and Hindu Kush Mountains (Weigle, 1999)”. They can also be found in Europe, North
America, and some in South America (Weigle, 1999).
Scientists have begun to study how the changes in climate are affecting a wide range of
species. There have been a wide variety of groups including plants and animals,
vertebrates and invertebrates, terrestrial and aquatic, and tropical and polar species that
have been monitored. They have looked at everything from physiology, phenology,
distribution, adaptation, community, and ecosystem structure. Climate plays an important
role when it comes to the distribution of organisms as can be seen by studying the
biomes. Significant shifts in distribution have been seen before as climate shifts have
occurred. Many organisms are able to shift with the changing climate and adapt to the
modification, while others cannot. Many of those who can’t are disabled by three main
causes; when there are reductions in species diversity through reductions in habitat size,
when warming exceeds the migrational capabilities of a species, and when there are
losses of habitat during progressive shifts of climatic conditions (GWTBD 4). The basic
theory behind the decline in patch area and associated species loss is associated with the
theory of island biogeography. “Biogeography is the study of the distribution of plants
and animals, the diverse spatial patterns they create, and the physical and biological
processes, past and present, that produce Earth’s species richness” (Christopherson,
2003). When further expanded to habitat destruction and disturbance of islands or
isolated areas, it is predicted that species diversity will decrease with decreasing island
size (5). This theory is thought to hold true similarly in reference to a patch of forest or
even in the ocean.
When discussing the dilemma of when warming exceeds migrational capabilities of
species there is much that we cannot understand or calculate. No one, at this point, is
entirely sure at what rate species will be able to migrate under such stresses. This makes
it difficult to predict a likely outcome if these events were to happen. Instead of actually
predicting how fast organisms will move, we can predict how fast organisms will have to
move in order to keep up. With the application of already established models able to
predict current and future distributions of major vegetation types, we can predict how fast
biomes will shift. With this accomplished, we could also get a general understanding of
how fast the species found within each of the biomes would also have to move. The
Kalafsky 24
species’ survival depends on their ability to remain in their shifted biome; it is unlikely
that they would survive in another biome. Fortunately, there are transition zones between
the biomes that allow for some leeway. The third event that species may have to deal
with is the loss of habitats during progressive shifts of climatic conditions. With this
issue, the main element restricting species movements is human induced. When biomes
shift they could potentially shift into areas that are fragmented by human variations of
land use. For example, land that is currently used for agriculture or urban areas would be
uninhabitable for most species. This fragmentation effect of these areas could potentially
result in species loss (GWTBD). “The pivotal importance of patchiness in the ecology of
individuals, populations, and communities is now widely recognized (Perrins et al
1991)”. Some distinct habitats in particular have been greatly destructed. These include
estuaries, ancient woodlands, and moorlands (Perrins et al, 1991). For conservation
practices, we must be concerned with both the size of patches and their separation
(Perrins et al, 1991). “The importance of distance between patches is emphasized by our
analysis of the cost of dispersal or migration between patches (Perrins et al, 1991)”. The
relative percentages of human disturbance by continent are displayed in the following
figure(Chapin et al, 2001).
According to the following figure, biodiversity continues to decrease as the negative
factors including mostly all human induced changes (directly or indirectly) overpower the
positive factors contributing to biodiversity (Chapin et. al, 2001).
Kalafsky 25
Specific examples of a variety of organisms are useful in observing trends of climate
change on species distributions. It is often predicted that organisms will move poleward
to compensate for the overall warming of temperature. Plants are interesting organisms to
monitor because they can’t physically get up and relocate as animals can, yet changes in
distributions have been observed. Plants require a certain amount of warmth to complete
their life cycle (Chapin et al, 2001)”. This “amount of warmth” can be measured by a
certain number of days above a certain temperature for example (Chapin et al, 2001)”.
Dispersal patterns and survival in the new environments are starting to be studied. For
example, tree species in the eastern U.S. have been documented to have moved poleward
(Iverson & Prasad, 2002). Unfortunately, it has been found that some plant species are
unable to establish populations in new areas when faced with climate change and habitat
fragmentation (Primack & Miao, 1992). Therefore, some of these plant species are
experiencing population declines or even extinctions. Lichens have also been monitored
and it seems that species that ordinarily have a subtropical distribution are invading more
poleward areas (van Herk et al. 2002). This poleward movement seems to make sense in
order to compensate for the temperature increase. With a latitudinal movement toward
the poles, there would likely be a few degrees decrease in temperature for the organism.
Kalafsky 26
The effects on animals can be studied more specifically in either terrestrial or aquatic
settings. The intertidal zone is also a great region to study. This zone is the transition
between the aquatic and terrestrial zone. These organisms are already subject to
conditions of great stress. They are subject to periods of desiccation and inundation, and
they have to deal with the salinity of the ocean as well. It has been proposed that the
animals in this region will be most affected by the effects of global warming. Stillman
has studied the effects of temperature changes in crabs in the intertidal zone (2002). In
addition to all the other conditions that these crabs must be adapted to, with temperature
change added in, there will likely be negative effects on the population. Insects are also
an important group of animals to consider. Changes in insect distributions can lead to
other human implications through the spread of diseases. For example, mosquitoes have
been reported at higher altitudes in Latin America and Africa, areas which already have
high instances of malaria (Hughes, 2000). With their population shift to higher latitudes,
people at these latitudes may be increasingly affected by the diseases such as malaria that
they carry. Lastly, corals are a very important example to look at for the effects of climate
change. They are already extremely sensitive organisms who are affected by even slight
natural changes in salinity or temperature. There have been many studies done to see the
effects of global warming on corals and the evidence suggests mass extinctions of certain
species (Hughes, 2000). There have been massive bleaching effects observed in corals
already. This bleaching happens when the zooxanthellae, the symbiotic algae critical for
the corals’ survival, leave the corals. Although the mechanisms of bleaching are poorly
understood, it is believed to be linked to temperature, salinity, toxicity, or light, or a
combination of these varied effects (Davidson, 1998). “Corals are, in a sense, the highwire artists of the sea, where only a slight misstep spells doom” (Davidson, 1998).
We have narrowed down our study from these categories and have chosen to primarily
look at the effects of climate change bird species distribution. “It has been argued that if
bird communities are protected, then many other communities will be protected, and that
evaluation of bird communities can be used as an indicator of the quality and
Kalafsky 27
conservation interest of the habitats (Spellerber, 1992)”. Birds are also becoming
increasingly well documented due to the international interest and cooperation of many
different countries and organizations (Spellerberg, 1992). Although population statistics
are for birds are difficult due to their mobile lifestyles (Spellerberg, 1992), birds are
excellent indicators of climate change because effects can be seen quickly. They have the
ability to relocate to more favorable or suitable conditions. “Bird species richness has
been related to vegetation height diversity (Chapin et al, 2001)”. Consequently, one
would expect bird populations to shift as vegetation patterns are shifting. Some studies
have found that bird distributions are most affected by climate and altitude (Storch et al,
2003). The climate factors have been studied by many and have found that not only do
bird distributions vary based on temperature but also largely on precipitation as well
(Githaiga-Mwicigi, 2002). The following graphs are from a study done on birds in
Mexico and show that there is a correlation between bird distribution and temperature
and precipitation (Gomez da Silva & Medellin, 2002).
The first graph had a p-value of <0.001 which indicates that temperature did have a
significant difference on bird species abundance (Gomez da Silva & Medellin, 2002).
The second graph had a p-value of 0.006, again indicating a significant effect of
precipitation on bird species abundance (Gomez da Silva & Medellin, 2002).
Birds have been subjected to changes due to habitat degradation along with these indirect
effects from humans such as climate change and other disturbances. When these factors
are coupled with limitations based on specialization, certain species are more influenced
than others (Julliard et al 2003). It is suggested that island or mountaintop species will be
particularly vulnerable to climate changes (Newton, 1998). As a general rule, if a habitat
is reduced in area by 50%, about 10% of the species will be lost, and if the habitat area is
reduced by 90%, about 50% of the species will be lost (Newton, 1998). Organisms in
tropical forests are in particular danger due to their high rates of habitat destruction
Kalafsky 28
(Newton, 1998). The importance of land area to characteristics such as species richness
can be seen in the following graph (MacDonald & Kirkpatrick, 2003).
Some of the island species that are now considered threatened are following the patterns
of those that have gone extinct in the last 400 years. Included in these are tube-nosed
petrels (Procellariidae), frigate birds (Fregatidae), pigeons (Columbidae), honey-eaters
(Meliphagidae), honey-creepers (Drepanididae), and wattlebirds (Callaeidae) (Newton,
1998). The Pacific Ocean alone is home to 110 of these threatened island species
(Newton, 1998). The following figure breaks down the threatened and extinct birds by
island regions (Newton, 1998).
Kalafsky 29
Contrastingly, some species of birds have been affected by the human suppression of
natural disturbances. For example, bird ecosystems are often regulated by events such as
fires or droughts. As humans subdue these natural disturbances, the ecosystems are bound
to be impacted (Brawn, et al. 2001). These natural disturbances are necessary for
regulating the environmental conditions of an area. For example, fires result in the
limiting of trees in grasslands as well as providing ashes which make fertile soil after
recovery. As natural disturbances help regulate and further characterize vegetation in
biomes, land-use is also studied in relation to species distribution as it directly impacts
vegetation. Venier et al. found that indeed land-use patterns do influence the distribution
of certain species of birds (2004). “With the increasing population pressures and the
development of modern agriculture, the sustainable use of biodiversity has lost its role in
these systems. This trend has rapidly led to the destruction of local and regional
biodiversity in agricultural systems and marginalized natural vegetation and wildlife as a
natural resource (Chapin et al, 2001)”. Land use change was found to be the driver with
the biggest impact on biodiversity according to biome model scenarios, followed by
climate change as the next most important (Chapin et al, 2001). This has to do primarily
with the greater impacts at higher latitudes. The following table illustrates their findings
on the drivers of biodiversity (Chapin et al, 2001).
Kalafsky 30
A negative consequence of the suppression of natural disturbances is that they are likely
to be more extreme and abundant as a side-effect. For example, with the suppression of
natural fires, land is likely to be drier and thus further promote larger fires in the future.
The prediction for increase in fires in the future is displayed in the following image
(Chapin et al, 2001).
The migratory patterns of birds can be tracked and their nests serve as important studies
on their hatching patterns. It has been suspected that breeding ranges would move upward
Kalafsky 31
in latitude or elevation due to the increase in temperatures. However, from some of the
studies so far, this theory has not yet been supported (Archaux, 2004). Bird experiments
have been well documented worldwide and thus we feel that they are an excellent group
to study in order to see how climate change can directly affect certain species’
distributions. From one of the studies that we found, from the Rocky Mountain Bird
Observatory, noticed what they found to be unusual bird patterns for the 2001 year. From
their bird banding study, they found high numbers of the following species: Western
Tanagers, Bullock’s Orioles, Yellow-rumped Warblers, and Western Wood Peewee
(Boulder County Nature Association, 2001). Some of the species that they found low
numbers or entirely missing include Northern Waterthrush and Blue Grosbeak (Boulder
County Nature Association, 2001). We chose five of the species from this study that we
knew to be migratory birds and compared their abundances from their data from 19912001. The species that we chose were the American Goldfinch, American Tree Sparrow,
Brown-headed Cowbird, Gray Catbird, and the House Wren. The American Goldfinch is
found in southern Canada and southern U.S. It migrates primarily in flocks during the day
(Bird Index). The American Tree Sparrow can be found in the summer in Alaska and
northern Canada and in the winter in southern Canada and the central U.S. (Bird Index).
The Brown-headed Cowbird is found primarily in North America, specifically in the U.S.
and Mexico and is known to migrate shorter distances (Chipper Woods Bird
Observatory). The Gray Catbird is found in southern Canada and eastern and central
U.S.(Bird Index). It American spends its winters in Panama and the West Indies. The
Gray Catbird migrates at night (Bird Index). The House Wren is commonly found from
central Canada to southern South America and in the summer specifically in the U.S. and
Canada (Bird Index).
Kalafsky 32
Fig 1. - contrasts bird abundance over time of five different migratory species common in
North America
Kalafsky 33
Although there seems to be great variability, there are some patterns worth noting. This
graph was taken from data collected semi-annually in the spring and fall between the
years of 1991-2001. The years of 1991-1995 were grouped and graphed together and
consequently most species had high numbers for the first 2 data points (corresponding to
1991-1995 spring and 1991-1995 fall, despite the label). Every increment after that goes
up by a half-year accordingly. The March and September labels were arbitrarily picked to
represent spring and fall respectively. Three of the species, the American Goldfinch, the
Gray Catbird, and the Brown-headed Cowbird had low numbers in the fall (September)
of 2000. We are attributing this to the wildfires in Colorado at this time. This makes
sense due to the location of the observatory (Rocky Mountain Observatory). Another low
time was in the fall of 1997 for all species. A number of bird species in this area show a
slight decrease in population, but as to why this slight decrease occureed the evidence is
inconclusive. Wildfires could potentially account for the drop off in 2000, but as for the
less dramatic fluctuations in population there could be many other compounding factors
influencing these events. The overall slight decline in bird populations could be
representative of events where birds are shifting out of their common habitats. One
would think that other populations of birds would move into the regions that were being
moved out of, but in the mountains of Colorado, where this study was conducted, the
actual presence of the mountains may be acting as geographic barriers impeding the other
species abilities to move into the given region.
It is important to understand how species numbers are estimated in order to know what
management approaches should be taken. One model for the population studies of birds
involves the following equation in their model: CV=_ni/Ni (Spellerberg, 1992). Here, CV
is the index, ni is the number of pairs of the ith species at a sit and Ni is the population
size of the ith species (Spellerberg, 1992). This study was done primarily in Western
Europe. Another more common one is the Shannon-Weiner indes of species diversity.
This model uses the equation H’= - _ pi (logPi) where Pi is the proportion of individuals
of species i in the sample (Spellerberg, 1992). These two models along with many others
have created useful data for the assessment of particular habitats. From these, the IUCN
and the IWRB (International Waterfowl Research Bureau) have identified internationally
important wetlands of Europe and North Africa (Spellerberg, 1992). Some of the criteria
used to identify an important wetland for the populations include: regularly supporting
1% of the biogeographical population of one species, supporting an appreciable number
of an endangered species of plant or animal, or playing a major role in that region for
scientific or economic importance (Spellerberg, 1992).
We conclude that species spatial distributions are directly effected by global warming and
subsequently climate change. In general terms it has been stated by the scientific
community that the distribution of species have been moving in a poleward trend. Within
the realm of our study we found no conclusive evidence to prove or disprove this
statement. The evidence that we did find and cited leads us to the conclusion that the
distribution of species is infact being altered by climatic change, but we were unable to
determine exactly what that change was. This project focused on bird species (as we
found they were ideal indicators of species shifts due to the fact that their patterns of
movement are already larger and more immediate than other organisms. This and the
fact that bird movements and migrations are well documented are the reason we chose to
focus our study on birds). Evidence found specifically from birds shows that there is a
Kalafsky 34
correlation between bird population characteristics and alterations in climatic factors such
as temperature and precipitation. The change in population characteristics shows that
some sort of shift or generally trended movement is occurring.
To contribute to the sustainable future which we all would like to see, we must work on
reducing our ecological footprint on the earth. An ecological footprint is “A measure of
human pressures on the natural environment from the consumption of renewable
resources and the production of pollution (Knox & Marston, 2004)”. This means trying to
conserve as many of the species of birds, and other organisms alike, for future
generations to come. The idea of sustainable development is “A vision of development
that seeks a balance among considerations of economic growth, environmental impacts,
and social equity (Knox & Marston, 2004)”. This should be a model for all nations and
organizations alike; to create a future in which a balance exists between the physical and
human worlds.
Management and conservation practices can make a difference. For example, Newton
illustrates examples of bird species (with their associated distribution ranges) that have
seen significant results in increasing population sizes due to management practices since
1950 (1998). Among these include the Whooping Crane, California Condor, Hawaiian
Crow, and Crested Ibis, just to name a few (Newton, 1998). Newton attributes the success
of these species to protection of the existing populations and ensuring suitable habitats
(1998). Most remarkable was the case of the Mauritius Kestrel. This species in 1974 only
had four individuals remaining (Newton, 1998). Through the success of a captive
breeding and release program, the number of individuals rose to 200+ by 1993 (Newton,
1998). From these examples, one can see that there is a chance to save the species which
are most affected by human disturbance and climate change. A good background and
understanding of species distributions is crucial for management and conservation
techniques. With greater public awareness and concern, we could alleviate some of the
problems that species are facing in response to global climate change; however, action
must be taken on the regional or local level to be successful.
As human population continues to increase, there will consequently be increasing impacts
on species worldwide. Habitat destruction and climate change will force species into
regions or situations that they will be forced to adapt to. Failure to adapt will lead to
declining populations and could result in a great loss of biodiversity. It is important to
acknowledge the impact that humans are having on species and also to work towards
reducing our "ecological footprint". This means countering destructive practices that
humans have engaged in for centuries. This is key for ensuring a sustainable future for
coming generations.
Kalafsky 35
Essay – Chapter 53
Tales of Nightmare Numbers
Across from Sausalito, California, the steep flanks of Angel Island rise form the waters of
San Francisco Bay. The island, set aside as a game reserve, escaped urban development.
It did not escape from the descendants of a few deer that well-meaning nature lovers
shipped over in the early 1900s. With no natural predators to keep themin check, the few
deer became many-far too many for the limited food supply of their isolated habitat. Yet
the island attracted a steady stream of picnickers from the mainland. They felt sorry for
the malnourished animals and made sure to load the picnic baskets with extra food for
them.
The visitors imported so much food that scrawny deer kept on living and reproducing. In
time, the herd nibbled away the native grasses, theroots of which had helped slow soil
erosion on the steep hillsides. Hungry deer chewed off all the new leaves of seedlings;
they killed small trees by stripping the bark and its phloem. The herd was destroying the
environment. In desperation, game managers proposed using a few skilled hunters to thin
the herd. They were strongly denounced as being cruel. They proposed importing a few
coyotes to the island to thin the herd naturally. Animal rights advocates opposed that
solution, also.
As a compromise, about 200 of the 300+ deer were captured, loaded onto a boat, and
shipped to suitable mainland habitats. A number of them received collars with radio
transmitters so that game managers could track them after the release. In less than 60
days, dogs, coyotes, bobcats, hunters, and speeding cars and trucks had killed off most of
them. In the end, relocating each surviving deer had cost taxpayers almost 3,000 dollars.
Kalafsky 36
The State of California refused to do it again. And no one else, anywhere, volunteered to
pick up future tabs.
It is not difficult to define the boundaries of Angel Island or track its inhabitants, so it is
easy to draw a lesson from this tale: A population’s growth depends on the resources of
its environment. And attempts to “beat nature” by altering the sometimes cruel outcome
of limited resources only postpone the inevitable. Does the same lesson apply to other
populations, inother places? Yes, it does, as the next tale makes clear.
When 1999 drew to a close, there were over 6 billion people on Earth. About 2 billion
already live in poverty. Each year 40 million more join the ranks of the starving. Next to
China, India is the most populous country, with more than a billion inhabitants. By 2010
there may be 182 million more. Forty percent of those people live in rat-infested
shantytowns, without enough food or fresh water. They are forced to wash clothes and
dishes in open sewers. Land available to raise their food shrinks by 365 acres a day, on
average. Why? Irrigated soil becomes too salty when it drains poorly, and there is not
enough water to flush away the salts.
Can wealthier, less densely populated nations help?After all, they use most of the world’s
resources. Maybe they should learn to get by more efficiently, on less. For example,
people might limit their meals to cereal grains and water; give up their private cars, living
quarters, air conditioners, televisions, and dishwashers; stop taking vacations, and stop
laundering so much; close all the malls, restaurants, and theatres at night; and so on.
Maybe wealthier nations also should donate more surplus food than they already donate
to less fortunate ones. Then again, would huge donations help, or would they encourage
dependency and spur more increases in population size? And what if surpluses run out?
In is a monumental dilemma. At one extreme, the redistribution of resources on a global
scale would allow the greatest number of people to survive, but at the lowest comfort
level. At the other extreme, foreign aid rationed only to nations that restrict population
growth would allow fewer individuals to be born, but the quality of life would be greater.
Currently, the foreign aid program of the United States is based on two premises: (1) that
individuals of every nation have an irrevocable right to bear children, even if unrestricted
reproduction ruins the environment that must sustain them; and (2) that because human
life is precious above all else, the wealthiest nations have an absolute moral obligation to
save lives everywhere.
Regardless of the positions that nations take on this issue, ultimately they must come to
terms with this fact: Certain principles govern the growth and sustainability of
populations over time. These principles are the bedrock of ecology – the systematic study
of how organisms interact with one another and with their physical and chemical
environment. Ecological interactions start within and between populations, and they
extend on through communities, ecosystems, and the biosphere.
Kalafsky 37
Essay – Chapter 54
NO PIGEON IS AN ISLAND
Flying through the rain forests of New Guinea is an extraordinary pigeon with cobalt blue
feathers and lacy plumes on its head. It is about as big as a turkey, and it flaps so slowly
and noisily that its flight sounds like an idling truck. As is true of eight species of smaller
pigeons living in the same forest, it perches on branches to eat fruit. How is it possible
that nine species of large and small fruit-eating pigeons live in the space of the same
forest? Wouldn’t you think that competition for food would leave one the winner? In fact,
in that rain forest, every species lives, grows, and reproduces in a characteristic way, as
defined by its relationships with other organisms and with the surroundings.
Big pigeons perch on the sturdiest branches when they feed, and they eat big fruit.
Smaller pigeons, with their smaller bills, cannot open big fruit. They eat small fruit
hanging from slender branches that are not sturdy enough to support the weight of a
turkey-sized pigeon. The species of trees in the forest differ with respect to the diameter
of their fruit-bearing branches and the size of their fruit. So they attract different pigeons
with different characteristics. Is such ways, the nine species of pigeons partition the fruit
supply.
And how do individual trees benefit from enticing the pigeons to dine? The seeds inside
their fruits have tough coats, which can resist the action of digestive enzymes inside the
pigeon gut. During the time it takes for ingested seeds to travel through the gut, the
pigeons fly about, so they dispense seed-containing droppings in more than one place. In
this way, the pigeons tend to disperse seeds some distance from the parent plant. Later,
when seedlings grow, the odds are better that at least some will not have to compete
with their parents for sunlight, water, and nutrients. Seeds that drop close to home cannot
compete in and significant way with the resource-gathering capacity of the mature trees,
which already have extensive, well-developed roots and leafy crowns.
Within the same forest, leaf-eating, fruit-munching, and bud-nipping insects interact with
other organisms and their surroundings in certain ways. So do nectar-drinking, flower
pollinating bats, birds, and insects. And so do great numbers of beetles, worms, and other
invertebrates that busily extract energy from remains and wastes of other organisms on
the forest floor. By their activities, they cycle nutrients back to the trees.
Like humans, then, no pigeon is an island, isolatedfrom the rest of the living world. The
nine species of New Guinea pigeons eat fruit of different sizes. They disperse seeds from
different sorts of trees. Dispersal influences where new trees will grow and where the
decomposers will flourish. Ultimately, tree distribution and decomposition activities
influence how the entire forest community is organized. Directly or indirectly,
interactions among coexisting populations organize the community to which they belong.
Kalafsky 38
Essay – Chapter 55/56
PHOSPHATE POLLUTION, ACID RAIN, AND THE
OZONE HOLE: HOPE FOR THE ECOSYSTEM RECOVERY?
A central message of chapter 54 is that energy flows and nutrient cycling are undergoing
extraordinary changes in ecosystems throughout the world. Although the outcome of
these changes is uncertain, it is important to recognize that humans have already
identified and acted on several recent changes in the abiotic environment that clearly had
negative consequences. The events and responses took place at the local, regional, and
global levels.
The first example of an effective response to an abiotic change took place at a local level
and involved a global nutrient cycle. Like many other elements and molecules,
phosphorus cycles through ecosystems. The use of phosphate-based detergents in the
industrialized countries led to a large increase in the concentrations of phosphate in lakes
and streams, triggering rapid and widespread eutrophication – particularly in shallow
lakes that received out-flow from municipal sewage systems. In response, governments in
North America and Western Europe encouraged or required the use of phosphate-free
detergents, and sewage plants were upgraded to remove more phosphate during
treatment. Although phosphate pollution from farm fertilizers remains a serious problem,
the crisis conditions of the 1960’s and 1970’s have largely been alleviated. The second
example involves changes in the pH of rainwater at a regional level. The problem began
with sulfur oxides and nitrogen oxides that are pumped into the atmosphere by coal
burning electrical power plants and vehicles that lack catalytic converters. When exposed
to sunlight and water vapor, the molecules react to form sulfuric acid (H2SO4) and nitric
acid (HNO3). Normal rainwater has a slightly acidic pH, about 5.6. But in areas affected
by acid rain, precipitation can have a pH as low as 4.2 or 4.4. During the 1980’s and the
1990’s, biologists documented that forests and lakes in eastern North America and
northern Europe were being affected by acid rain.
Tree growth slowed in response to the acidification of soils, and lakes became less
productive and less diverse. Once biologists had documented the problem, governments
instituted stricter controls on the amounts of sulfur oxides and nitrogen oxides that could
be emitted from power plants, cars, and trucks. Over the past decade, the intensity of acid
rain has diminished and some of the ecosystems that were being affected have begun to
recover.
A third example involves changes in atmospheric chemistry that were global in scale.
Widespread use of the compounds called chlorofluorocarbons (CFCs) in refrigeration and
aerosol products resulted in the release of thousands of tons of CFCs into the atmosphere.
When CFCs accumulated in the upper atmosphere, they participated in chemical
reactions that released chlorine atoms. These chlorine atoms subsequently reacted with
ozone (O3) molecules, which also accumulate in the upper atmosphere. In some years,
the loss of ozone due to these reactions was so severe that an ozone hole opened over
Antarctica. This issue concerned scientists from around the world, because ozone absorbs
large amounts of ultraviolet (UV) radiation. When the ozone layer that surrounds Earth
thins or is wiped out, an excess of UV radiation can reach Earth’s surface and act as a
mutagen and carcinogen. Fortunately, soon after the problem was documented in the
Kalafsky 39
early 1990’s, international treaties scheduled and enforced the rapid phasing out of CFC
productions and use. Scientists have recently been able to document the first signs that
the size and duration of the ozone hole may be moderating.
The message of these examples is clear: Effective responses have occurred at the local,
regional, and global levels when biologists documented serious problems in ecosystem
ecology. It remains to be seen whether the same success can be achieved in response to
global warming, nitrate pollution, and other current problems in the abiotic environment.
Essay – Chapter 55/56
EXOTIC AND ENDANGERED SPECIES
When you hear someone bubbling enthusiastically about an exotic species, you can safely
bet the speaker is not an ecologist. This is a name for a resident of an established
community that has moved from its home range and successfully taken up residence
elsewhere. It makes no difference whether the importation was deliberate or accidental.
Unlike most imports, which cannot take hold outside their home range, an exotic species
insinuates itself into the new community.
Sometimes the additions are harmless and even have beneficial effects. More often, they
make native species endangered species, which by definition are extremely vulnerable to
extinction. Of all species that are now on rare or endangered lists or have already become
extinct, close to 70 percent owe their precarious existence or demise to displacement by
exotic species.
HELLO VICTORIA, GOOD-BYE CICHLIDS.
Finding better ways to manage our food supplies is essential, given the astounding
growth rate of the human population. Such efforts are well intentioned, but they can have
disastrous consequences when ecological principles are not taken into account. For
example, several years ago, someone thought it would be a great idea to introduce the
Nile perch into Lake Victoria in East Africa. People had been using simple, traditional
methods of fishing there for thousands of years. Now they were taking too many fish.
Soon there would be too few fish to feed local populations and no excess catches to sell
for profit. But Lake Victoria is a very big lake, and the Nile perch is a very big fish (more
than two meters long). A big fish in a big lake seemed like an ideal combination to attract
commercial fishermen with big, elaborate nets from the outside world – right? Wrong.
Native fishermen had been harvesting native fishes called cichlids, which eat mostly
detritus and aquatic plants. The Nile perch eats other fish – including cichlids. Having
had no prior evolutionary experience with the new predator, the 200 coexisting species of
cichlids that were native to Lake Victoria had no defenses against it.
And so the Nile perch ate its way through the cichlid populations and destroyed the lake’s
biodiversity. Dozens of cichlid species found nowhere else are extinct. Without the
cichlids to clean up the lake bottom, levels of dissolved oxygen plummeted and
contributed to frequent fish kills. By 1990, fishermen were catching mostly Nile perch.
Now there are signs that the Nile perch population is about to crash. By destroying its
Kalafsky 40
food source, the Nile perch has undercut its own population growth. It has ceased to be a
potentially large, exploitable food source for the people who live around the lake.
As if that weren’t enough, the Nile perch is an oily fish. Unlike cichlids, which can be
sun dried, the Nile perch must be preserved by smoking – and smoking requires
firewood. Local people started cutting down more trees in the local forests, and trees are
not rapidly renewable resources. To add insult to injury, the people living near Lake
Victoria never liked to eat Nile perch anyway. They prefer the flavor and texture of
cichlids.
What is the lesson? A little knowledge and some simple experiments in a contained
setting could have prevented the whole mess at Lake Victoria.
THE RABBITS THAT ATE AUSTRALIA.
During the 1800’s, British settlers in Australia just couldn’t bond with koalas and
kangaroos, so they started to import familiar animals from their homeland. In 1859, in
what would be the start of a wholesale disaster, a landowner in northern Australia
imported and released two dozen wild European rabbits. Good food and good sport
hunting, was the idea. An ideal rabbit habitat with no natural predators – that was the
reality.
Six years later, the landowner had killed 20,000 rabbits and was besieged by 20,000
more. The rabbits displaced livestock, even kangaroos. Now Australia has 200 to 300
million hippity-hopping through the southern half of the country. They overgraze
perennial grasses in good times and strip bark from shrubs and trees during droughts.
You know where they’ve been; they transform grasslands and scrublands into erode
d deserts. They have been shot and poisoned. Their warrens have been plowed under,
fumigated, and dynamited. Even when all-out assaults reduced their population size by 70
percent, the rapidly reproducing imports made a comeback in less than a year. Did the
construction of a 2,000-mile-long fence protect western Australia? No. Rabbits made it to
the other side before workers completed the fence.
In 1951, government researchers introduced myxoma virus by way of mildly infected
South American rabbits, its normal hosts. This virus causes myxomatosis. The disease
has mild effects on the South American rabbits that coevolved with the virus but nearly
always had lethal effects on the European rabbits. Biting insects, mainly mosquitoes and
fleas, quickly transmit the virus from host to host. Having no coevolved defenses against
the novel virus, the European rabbits died in droves. As you might expect, natural
selection has since favored rapid growth of populations of the European rabbits that are
resistant to the virus.
In 1991, on an uninhabited island in Spencer Gulf, Australian researches released a
population of rabbits that they had injected with a calicivirus. The rabbits died quickly
and relatively painlessly from blood clots in their lungs, heart, and kidneys. In 1995, the
test virus escaped from the island, possibly on insect vectors. It has been killing 80 to 95
percent of the adult rabbits in Australian regions. At this time, researchers are now
questioning whether the calicivirus should be used on a widespread scale, whether it can
Kalafsky 41
jump boundaries and infect animals other than rabbits (such as humans), and what the
long-term consequences will be.
THE PLANTS THAT ATE GEORGIA.
A vine called kudzu (Pueraria lobata) was deliberately imported from Japan to the United
States, where it faces no serious threats from herbivores, pathogens, or competitor plants.
In temperate parts of Asia, kudzu is a well-behaved legume with a well-developed root
system. It seemed like a good idea to import it for erosion control on hills and near
highways in the southeastern United States. However, with nothing to stop it, kudzu’s
shoots can grow one-third of a meter per day. Vines now blanket stream banks, trees,
telephone poles, houses, hills, and almost everything else in their path. Attempts to dig
them up or burn them are futile. Grazing goats and herbicides help, but goats are
indiscriminate eaters and herbicides contaminate water supplies. If the global temperature
continues to rise, kudzu could reach the Great Lakes by the year 2040.
On the bright side, a Japanese firm is constructing a kudzu farm and processing plant in
Alabama. Asians use a starch extract from kudzu in beverages, candy, and herbal
medicines. The idea is to export the starch to Asia, where the demand currently exceeds
supply. Also, kudzu might eventually help reduce the extent of logging operations. At the
Georgia Institute of Technology, researches have reported that kudzu may be used as an
alternative source of paper.