Biology 102
Spring Quarter
Written by: Sue Kloss
Lake Tahoe Community College
Instructor: Sue Kloss
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Chapter 50 – Ecology
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Intro - Ecology is the study of organisms, their abiotic environment and the relationships between orgs and their
env. And orgs and each other.
A. Ecology and evolutionary biology
1. ecology is the current process of what will, over time, become evolution
2. predator-prey interactions may affect the process of natural selection over a long time
B. Organisms and the environment-a community is all the organisms inhabiting a particular area (biota)
1. population is all the members interacting from a particular species in an area
2. community is assemblage of all potentially interacting groups of species in an area
a. characteristics include prevalent form of vegetation, response to disturbance, diversity, trophic
structure
3. distribution and abundance of organisms is a frequently addressed question in ecology
a. Red Kangaroos are distributed according to amt and variability of precipitation (Fig 50.2)
b. From this info, though, its impossible to know if biotic factors also limit distribution eg a parasite
only found in wetter areas
C. Subfields of ecology
1. organismal ecology – study of organism and relationship to its environment
a. may be physiology, behavioral, evolutionary ecology
2. population ecology – study of factors that affect no. of individuals of a species living in an area
3. community eco- study of interactions of various species or with abiotic factors of organisms living in
an area
4. ecosystem ecology – study of energy flow and chemical cycling in a particular ecosystem
5. landscape ecology – arrays of ecosystems and how they are arranged in a geographic area;
mosaics of patches. Studies focus on factors controlling energy, nutrients and organisms
6. biosphere – thin skin of earth that supports life, several km above and below earth
7. Ecology and the environment – “the ecology” is not the environment
II. Interactions of organisms and their environments limit distribution of species
A. Biogeography- study of past and present distribution of species in an evolutionary context – good
starting point for understanding the limits of geographic distribution of species
B. Dispersal and Distribution (fig. 50.5) Flow chart may help find answers (Fig. 50.6)
1. dispersal - movement of individuals away from areas of high pop density. Why no kangaroos in
North America? May be barriers to dispersal here from Australia
a. natural range expansion – long distance capable organisms get around (fig. 50.7)
b. species transplants – documented when it occurs, not done purposely today as in past
C. Behavior and Habitat Selection
1. by plants (eg. – seed germination characteristics) and animals (eg – birds select nest sites)
D. Biotic Factors – may limit distribution- predation, parasitism, disease, competition- eg. Sea urchins limit
certain seaweed species (Fig. 50.8)
a. exotic introductions can alter species distribution and species relationships eg white pine blister
rust
E. Abiotic Factors
1. temperature – must be within species autecological range
2. water – if fresh or saltwater dependent, or freezing or availability may affect distribution
3. sunlight – for Ps, also for correct development of most individuals, plus for orgs with photoperiod
requirements
4. wind – amplifies temperature – convection heating or wind chill, also imp. For dispersal or flagging
(fig. 50.9)
5. rocks and soil – pH and mineral composition may limit many plants, or affect water avail.
F. Climate
1. global climate patterns – due to differential warming of sun on earth, and earth’s movement
through space (fig. 50.10)
2. regional, local season climate - proximity to water, topography and area of earth
a. bodies of water – banana belt in Keys (fig. 50.11)
b. mountains - topography (Fig. 50.12)
c. seasonality – changing angle of sun over a year (Fig. 50.13)
3. microclimate- topographic position, low spot in a meadow; small scale differences
4. long term climate change – beech must migrate 7 – 9 km/yr, but is apparently capable of
migrating about .2 km/yr
III. Aquatic biomes – (fig. 50.17)
IV. climate determines terrestrial biomes (fig. 50.18, 19, 20)
Learning Objectives Ch. 50
1. Define ecology. Identify the two features of organisms studied by ecologists.
2. Describe the relationship between ecology and evolutionary biology.
3. Distinguish between abiotic and biotic components of the environment.
4. Distinguish among organismal ecology, population ecology, community ecology, ecosystem ecology, and
landscape ecology.
5. Clarify the difference between ecology and environmentalism.
6. Define biogeography.
7. Describe the questions that might be asked in a study addressing the limits of the geographic distribution of a
particular species.
8. Describe the problems caused by introduced species and illustrate with a specific example.
9. Explain how habitat selection may limit distribution of a species within its range of suitable habitats.
10. Describe, with examples, how biotic and abiotic factors may affect the distribution of organisms.
11. List the four abiotic factors that are the most important components of climate.
12. Distinguish between macroclimate and microclimate patterns.
13. Provide an example of a microclimate.
14. Explain, with examples, how a body of water and a mountain range might affect regional climatic conditions.
15. Describe how an ecologist might predict the effect of global warming on distribution of a tree species.
16. Name three ways in which marine biomes affect the biosphere.
Ch. 51Behavoiral Ecology
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Introduction: Animal behavior is closely tied to ecology and evolution. It is broadly defined as externally
observable muscular activity, triggered by an external stimulus. More or less, it is what an animal does when
interacting with its natural environment.
People throughout history have been remarking on and documenting animal activities, but behavioral biology, the
science of behavior, was not established until the 20th century. Nobel laureates Karl von Frisch, Konrad Lorenz
and Niko Tinbergen were some of the first pioneers in the field.
I. Proximate vs. Ultimate causes of behavior
A. What is behavior?
1. behavioral traits are phenotype as much as color or size, most the result of muscular activity
2. behavior can also be nonmuscular - when animal secretes a hormone to attact mate
3. learning is considered behavior
4. ecologists also study the mechanisms underlying these behaviors
5. behavior may be thought of as anything an animal does and how it does it
B. Proximate and Ultimate Questions
1. Proximate questions ask about behavior that focus on the environmental stimuli that trigger
a behavior as well as the genetic, physiuoogical and anatomical mechansism underlying a
behavioral act
2. Proximal questions are “how” questions e.g. how does day length influence breeding in cranes
3. reasonable hypothesis - breeding is triggered by effect of increased day length on animal’s
production and response to particular hormones
4. various experiments demonstrate that daily lengthening exposure to light produce neural and
hormonal changes that induce behavior associated with reproduction - singing, nest building, etc
5. Ultimate questions address the evolutionary significance of a behavior. eg. why did natural
selection favor this behavior and not a different one?
6. behavior should increase fitness in some way
7. a reasonable hypothesis for why cranes reproduce in spring and early summer is most food is
available for rapidly growing young
C. Ethology - scientific study of how animals behave, pioneered in mid 60s. - Tinbergen of Netherlands,
von Frisch andLorenz of Austria shared a Nobel prize in 1973.
1. Core of behavioral ecology in 1963 paper by Tinbergen
a. What is the mechanistic basis of the behavior- chemical, anatomical and physiological
mechanisms?
b. How does development of animal (zygote - mature adult) influence the behavior?
c. What is the evolutionary history of the behavior?
d. How does the behavior contribute to survival and reproduction (fitness)?
2. this list includes both proximate and ultimate causes of the behavior
3. Fixed Action Patterns (FAP)- sequence of unlearned behavior
a. essentially unchangeable and once initiated, usually carried to completion
1. sticklebacks attack invading males to territory (Fig. 51.3)
2. sign stimulus - an external sensory stimulus that triggers FAP
b. in sticklebacks, color red stimulates FAP- chasing away intruders (Fig. 51.4) explains
both proximate and ultimate causes
c. greylag goose/egg rolling is another example
d. FAPs are genetically programmed nervous pathway
e. Advantages? No need to take time for learning in vital skills/processes
4 . Imprinting - a type of behavior that includes both learning and innate components and is
generally irreversible (Fig. 51.5)
a. sensitive period - time in animal’s development that is the only time when certain
behaviors can be learned
b. e.g. young geese follow their mothers and learn basic behaviors of species
c. parents bond to young and learn to recognize them e.g. among gulls, sensitive period
is one to two days, if bonding does not occur, parent will not initiate care of the infant,
leading to certain death of the infant
d. cranes have been imprinted on biologists in crane suits and taught new migration
routes (Fig. 51.6)
e. salmon imprint smell of stream early in life, can navigate back there
II. Many behaviors have a strong genetic component
A. Directed movements - kineses and orientation place animals in favorable environments
1. kinesis- random movements - e.g. sow bugs randomly move more in dry environments,
increasing the chance they will find a moist, more favorable environment (Fig. 51.7)
a. so do body lice
2. orientation behavior - animal places its body in a specific position relative to an env. cue
a. taxis - automatic movement directed to or away from a stimulus
1) trout- rheotaxis- orient themselves toward flowing water
2) chemotaxis - chemical signal orients you to mate
3. orienting behavior much more tuned to environment, and so more prevalent than kineses
B. Migration depends on internal maps (fig. 51.8)
1. cognition- the ability of an animals nervous system to perceive, store, process and use
information gathered by its sensory receptors
2. cognitive ethology - study of animal cognition - includes animal awareness
3. cognitive maps- internal representations or codes of spatial relationships among objects in
their surroundings a. Kamil from U of Nebraska - pinyon jays and Clarks nutcrackers - observed that
these birds could establish rules and apply a general abstract rule to locate a seed
cache - “seed caches are located halfway btn. partic. landmarks”
4. Seasonal migration - regular back and forth movement of animals between two areas at
particular times of the year
a. Enables animals to access rich food sources
b. breed or winter in favorable surroundings
c. whale migrations from AK to Baja
d. large populations of insects in N. hemisphere in spring and summer, draws birds
e. monarch butterfly - Winter in Cuba, Mexico, and a few places in California. In late
summer, all N. America’s monarchs migrate to these sites. They remain in trees for
4-5 months and live off food they’ve stored, they don't eat. Wintering sites have to be
cool enough to not metabolize stored food before spring, but not so cold that they freeze.
In spring, they mate and begin migrating north. As they arrive in regional destinations,
they lay eggs and die. Two or more generations are produced during summer,
repopulating Canada and U.S. As summer ends, they fly back to winter grounds, but
they've never flown the route before.
f. how do they orient? grey whales seem to use the N. American Pacific Coast, stick
heads out of water
g. many birds migrate at night, using the stars- bird migratory experiment (Fig. 51.21)
h. magnetite found in the heads of some birds and insect
C. Animal Communications and signals
1. signal causes a change in another animal’s behavior
2. communication - transmission, response to, and change in behavior due to a signal
a. many fish will erect their fins, often enough to drive away intruder - lower energy costs
than fighting
b. may be visual, auditory, chemical, tactile, or electrical
1. nocturnal animals don't use visual signals, tend to use olfactory and auditory
most mammals are nocturnal
2. birds use auditory and visual signals- they are diurnal
3. if we had well developed olfactory senses, the world would appear very
different to us
3. chemical communication
a. pheromones - chemicals for communication, genetically controlled, for most part
1. especially common among mammals and insects, often reproductive
2. moths can attract mates from several kilometers away
3. pheromones can also institute courtship behavior
4. pheromones can induce a fright response (Fig. 51.9)
a. just 1 cm2 of skin in fathead minnows can induce rxn even if diluted by
58k liters of water
2. Auditory communication
a. songs of most bird species are at least partly learned
b. insects of many spp. have songs under direct genetic control
1. drosophila - songs in wing beats - males reared in isolation can perform song
2. lacewings - dift. spp in same habitat (sympatric) have different songs
(behavioral isolation)
a. Henry of Uconn never observed hybrids in wild, but in lab could mate
them and have hybrid songs (Fig. 51.10)
D. Genetic influence on mating and parental behavior
1. many mammal behaviors under relatively strong genetic control
2. mating and parenting by prairie voles
a. these are monogamous (only 3% of mammals are monogamous)
b. males help care for young, also uncommon among male mammals
c. form strong pair bonds, grooming and huddling (fig. 51.11)
d. found to be under control of apparently a single gene (neurotransmitter that they
injected into mice who developed the same behaviors)
III. Environment interacting with genetics influence development of behavior - environment modifies many
behaviors that have genetic basis
A. Dietary influences in mate selection
1. drosophila in desert feeding on rotting cactus - females from one pop will avoid males that feed
on partic. species of cactus, tends to be associated w/ available food for that population
2. Hydrocarbon chains structure - proximate cause (Fig.; 51.13) - sprayed males with “right”
hydrocarbons and then mating chances equaled males from females pop
B. Social environment and aggressive behavior
- mice of different species cross fostered showed
tendencies of foster families in aggressive behaviors
C. Learning
1. habituation - scare crows, white noise, hydra touched repeatedly; allows animal’s nervous
system to focus on stimuli that may be more relevant to survival and reproduction
2. spatial learning - modification of behavior based on spatial structure of environment
a. Tinbergen classic experiment - (Fig 51.14)
3. associative learning - associates one feature of env. with another - e.g. bright colored
caterpillar or butterfly = bad taste and toxic
a. classical conditioning - arbitrary stimulus is associated with reward or punishment
b. operant conditioning- animals own behavior is associated with rewared or punishment
(fig. 51.16)
5. cognition and problem solving - cognition - animals nervous system can perceive, store,
process and use info gathered by sensory receptors
a. novel problem solving- solve a problem you have never been exposed to
b. may solve problem by copying another animal (Fig. 51.17)
6. genetic and environmental interaction in learning - considerable research on bird songs shows
a large amount of variability in genetic vs. environmental factors in learning complex behaviors
a. How much of artistry (a world class pianist) is the result of genes, how much from hard
work?
b. Is the capacity for hard work genetic?
c. in biology, it’s not a question of nature vs. nurture, but what degree of each is involved
1. fishers lovebird carries long strips in beak
2. peach faced lovebird carries short strips under back feathers
3. hybrids tries to tuck intermediate strips under feathers; when it fails, in beak
Objectives Ch. 51
1. Define behavior.
2. Distinguish between proximate and ultimate questions about behavior. Ask a proximate question and an
ultimate question about bird song.
3. Explain how the classical discipline of ethology led to the modern study of behavioral ecology.
4. Define fixed action patterns and give an example.
5. Define imprinting. Suggest a proximate cause and an ultimate cause for imprinting in young geese.
6. Explain how genes and environment contribute to behavior. Explain what is unique about innate behavior.
7. Distinguish between kinesis and taxis.
8. Distinguish between signal and pheromone.
9. Explain how Berthold’s research demonstrated a genetic basis for blackcap migration. 10. Describe research
on the genetic and physiological controls on parental behavior of prairie voles. Describe Bester-Meredith and
Marler’s research on the influence of social behavior on parental behavior of California mice
11. Explain how habituation may influence behavior.
12. Describe Tinbergen’s classic experiment on spatial learning in digger wasps.
13. Distinguish between landmarks and cognitive maps.
14. Describe how associative learning might help a predator to avoid toxic prey.
15. Distinguish between classical conditioning and operant conditioning.
16. Describe an experiment that demonstrates problem solving in nonhuman animals.