Unit 2 Biological Diversity Study Guide
1. What is biodiversity? What is the underlying cause of biodiversity?
 Biodiversity is the variability among living organisms from all sources, including terrestrial,
marine, and other aquatic ecosystems and the ecological complexes of which they are part;
this includes diversity within species, between species, and of ecosystems.
 Biodiversity forms the foundation of the vast array of ecosystem services that critically
contribute to human well-being.
 Biodiversity is important in human-managed as well as natural ecosystems.
 Decisions humans make that influence biodiversity affect the well-being of themselves and
others.
2. What is the underlying cause of biodiversity?
http://www.eco-question.com/what-are-the-main-causes-of-biodiversity-loss
 Habitat loss and destruction
 Alterations in ecosystem composition
 Over Exploitation
 Invasive species
 Pollution and contamination
 Global climate change
3. Biological diversity involves the following concepts. Explain each:
 Genetic diversity – variety of genes in a species to allow for it to have an reproductive
advantage
 Habitat/ecosystem diversity- large area with different biomes for organisms to thrive
 Species diversity- number of different species and their abundance.
4. Why is biodiversity high in some places but low in others?
 Unique Climates and Conditions
One of the most significant and naturally occurring causes of differences in biodiversity across
the world is differences in climate. Mountain tops and deserts are naturally low in biodiversity,
for the simple reason that their unique climates are not suitable to many types of life. Plants and
animals have as much difficulty surviving in the thin atmosphere on freezing mountain tops as
they do living in hot, waterless deserts. As such, these climates support very low biodiversity.
On the other extreme, moist, tropical zones like the Amazon rainforest support some of the
highest levels of biodiversity in the world. Numerous varieties of plants and animals can thrive
in these environments.
 Pollution and Environmental Destruction
Even in the most biodiverse regions of the world, like rainforests, human pollution can reduce
biodiversity. This is because pollution does not uniformly affect all species. Some species, for
example, might be more resistant to the impact of a toxic oil in a water supply, while another
species might be killed almost to extinction because of the pollutant. The loss of a single species
can throw off a food web, and lead organisms that relied heavily on that species as a source of
food to also die. In the process, numerous species may die or even go extinct, which reduces
biodiversity considerably.
 Invasive Species
Invasive species are another type of environmental factor that can vastly reduce biodiversity.
While invasive species are frequently introduced by humans, they sometimes occur naturally.
Introducing a new species to an new environment can often lead to a disruptive change in food
webs, which can reverberate throughout a region and cause numerous other species to go
extinct. In the 1950's, for example, British colonists introduce a species of perch into Africa's
Lake Victoria, and the perch killed off numerous other species in the lake. The fish that the
perch killed, in turn, no longer ate the algae that grew in the lake, so the algae population
bloomed and then decayed, resulting in decreasing oxygen levels in the lake, which then
became inhospitable to many forms of life. This is an example of how one small invasive
species can turn a high biodiversity region into a low one. (A local example would be the zebra
muscles that are invaiding local lakes.)
 Overhunting or Overuse
Overhunting or overuse of a species can have the same adverse impact on biodiversity as an
invasive species or pollution. Overusing or overhunting just one species in an ecosystem can
disrupt food chains and impact the ability of numerous other species to survive. But sometimes
the threat is not due to food web disruption. In the Amazon rainforest, for example, the spider
monkey plays an important role in helping the the tree species Inga ingoides survive by
distributing its seeds manually and through feces. As the spider monkey has been hunted almost
to extinction, the Inga ingoides have largely failed to reproduce, and thus have also declined in
population. The overhunting of just one species can thus rapidly reduce the entire biodiversity
of a region.
5. Why is biodiversity important in an ecosystem?
 Biodiversity and food: 80% of human food supply comes from 20 kinds of plants. But
humans use 40,000 species for food, clothing and shelter. Biodiversity provides for variety
of foods for the planet.
 Biodiversity and human health: The shortage of drinking water is expected to create a
major global crisis. Biodiversity also plays an important role in drug discovery and
medicinal resources. Medicines from nature account for usage by 80% of the world’s
population.
 Biodiversity and industry: Biological sources provide many industrial materials. These
include fiber, oil, dyes, rubber, water, timber, paper and food.
 Biodiversity and culture: Biodiversity enhances recreational activities like bird watching,
fishing, trekking etc. It inspires musicians and artists.
6. What are the characteristics of an endangered species?
http://www.ehow.com/info_7840074_characteristics-common-endangered-species.html
Endangered species are animals or plants that are so few in number that it is possible they may
become extinct in the near future. A species can become endangered due to changes in the
environment, predators, disease, or from the impact of humans. While a wide variety of species
have become extinct -- from the Tasmanian tiger to the Dodo bird -- they do share some
common characteristics.
 Habitat: Animals or plants that live in a small area, such as an island or cave, are vulnerable
to extinction. They may be unable to relocate or adapt to changes in their environment.
Species that have a specialized habitat, such as marshes, are also at risk. For example, the
Ivory-billed Woodpecker needs old-growth forests, which when cut for lumber cannot
quickly be replaced. Many bat species dwell in caves and cannot easily find new homes.
 Diet: The more limited the diet of a species, the more likely it is to become extinct. General
herbivores, which eat a wide variety of plants, are better able to find food when their
environment changes than a species such as the Giant Panda, which eats mainly the slowgrowing bamboo plant. The black-footed ferret survives almost entirely on prairie dogs,
which are viewed by farmers and ranchers as a pest that threatens their livestock.
 Reproduction: Species that live a long time and have few young are vulnerable to
extinction. They are not as resilient to population losses as fast-reproducing species. For
example, small rodents have a high mortality rate and have large litters, sometimes multiple
times a year. Larger animals that face fewer predators tend to produce fewer offspring.
Some produce just one offspring at a time and do not reproduce every year.
 Size: Larger animals are more vulnerable to extinction. They require larger habitats in
which to find food and mates. Mountain lions have territories of up to 116 square miles (300
square km).
 Commercial Value: Animals or plants that are sought after as pets or for their commercial
value have often faced extinction. Rhinoceros are often hunted for their horns, which are
considered an aphrodisiac in some cultures. The Sturgeon fish, a source of caviar, is now
endangered due to overfishing. Many species of tiger have become extinct or are
endangered because of demand for their fur.
7. What is the current reasoning as to why things are becoming extinct at such a fast rate?
Human interactions and population growth – Conservationists say rate of new species slower
than diversity loss caused by the destruction of habitats and climate change
8. What is the main reason for the sixth mass extinction?
 The Earth's sixth mass extinction is already underway — and humans are the driving force
behind it, according to a new study. The researchers say “human activities are driving the
latest mass extinction event. A ballooning human population, habitat destruction to make
way for new settlements or agricultural production, climate, ocean acidification, and soil,
water, and air pollution are all wiping species off the face of the Earth.”
 "Recent extinction rates are unprecedented in human history and highly unusual in Earth's
history," according to a study in the journal Science Advances. "Our global society has
started to destroy species of other organisms at an accelerating rate, initiating a mass
extinction episode unparalleled for 65 million years."
 Researchers used "extremely conservative assumptions" to determine extinction rates that
prevailed in the past five annihilation events. Still, they found the average rate of vertebrate
species lost over the past century was up to 114 times higher than normal.
9. List 3 endangered species.
Asian Elephant, Black rhino, Indian Tiger
10. Summarize the Endangered Species Act.
The Endangered Species Act of 1973 (ESA) was signed on December 28, 1973, and provides
for the conservation of species that are endangered or threatened throughout all or a significant
portion of their range, and the conservation of the ecosystems on which they depend. The ESA
replaced the Endangered Species Conservation Act of 1969. Congress has amended the ESA
several times.
 It is illegal for Americans to import or trade in any product made from an endangered or
threatened species unless it is used for an approved scientific purpose or to enhance the
survival of the species.
 Authorizes the Marine Fishery Service and the U.S. Fish and Wildlife Service to identify
and list all other endangered & threatened species.
 These species cannot be hunted, killed, collected or injured in the U.S.
11. Explain in situ vs ex situ.
In Situ would be trying to help a threatened species recover in their natural habitat leaving it
there and protecting it with laws. Ex situ would be to bring them out of their habitat to a zoo or
animal preserve to be cared for.
12. How do scientists account for the development of life on earth?
Using the fossil record, DNA & chemical analysis and ice cores.
13. What is biological evolution by natural selection, and how can it account for the current
diversity of organisms on the earth?
Biological evolution, refers to the change of living things over time. Charles Darwin concluded
that biological evolution occurs as a result of natural selection, which is the theory that in any
given generation, some individuals are more likely to survive and reproduce than others. In order
for natural selection to occur in a population, several conditions must be met:
 Individuals in the population must produce more offspring than can
survive. Human beings are somewhat unique among living things in that we can make
conscious choices about how many offspring we have. Most other organisms, however,
produce as many offspring as they can.
 Those individuals must have different characteristics. During Darwin’s time, no one
knew where these differences came from. Now scientists know that differences in
organisms arise due to mutations in DNA combined with the mixing of genetic
information during sexual reproduction.
 Offspring must inherit some characteristics from their parents.During Darwin’s
time, the laws of inheritance were just beginning to be figured out, so Darwin didn’t
know exactly how parents passed on their traits. Modern scientists know that traits are
inherited when parents pass genes on to their offspring.
 Organisms with the best-suited characteristics for their environment are more
likely to survive and reproduce. This is the heart of natural selection. If there’s
competition for survival and not all the organisms are the same, then the ones with the
advantageous traits are more likely to survive. If these traits can be inherited, then the
next generation will show more of these advantageous traits.
If these four conditions are met, then the new generation of individuals will be different from the
original generation in the frequency and distribution of traits. This is the theory we use to
account for all biodiversity on Earth.
14. How do extinction of species and the formation of new species affect biodiversity?
As environmental conditions change, the balance between formation of new species and
extinction of existing species determines the earth's biodiversity.
15. How did we become such a powerful species in a short time?
Humans have survived and thrived because we have certain traits that allow us to adapt and
modify parts of the environment to increase our survival chances. Evolutionary biologist
attribute our success to three adaptations:
 Strong oppossiable thumbs that allow us to use tools
 Ability to walk upright which frees up our hands and give us great agility
 Complex brains which allows us to develop many skills, including the ability to use
speech to transmit complex ideas
16. How have human activities affected the Earth’s biodiversity?
There is no doubt that human civilization has had a negative impact on biodiversity, particularly
since the industrial revolution. Overfishing and hunting, the destruction of habitats through
agriculture and urban sprawl, the use of pesticides and herbicides, and the release of other toxic
compounds into the environment have all taken their toll, particularly on vertebrates.
17. How serious is tropical deforestation?
Deforestation may meets some human needs, it has profound, sometimes devastating,
consequences, including
 social conflict
 extinction of plants and animals
 climate change
 Reasons for tropical deforestation:
o The poor become subsistence farmers to feed their families
o Government subsidies make the wood cheaper
o Governments give title to the land where the poor clear and colonize the land
o Easy financing of large scale projects in rainforest areas for developing countries
o Failure to value ecological services of forests
18. How can we sustain tropical forest?
Strategies for preserving tropical forests can operate on local to international scales.
 On a local scale, governments and non-governmental organizations are working with forest
communities to encourage low-impact agricultural activities, such as shade farming, as well
as the sustainable harvesting of non-wood forest products such as rubber, cork, produce, or
medicinal plants. Parks and protected areas that draw tourists—ecotourism—can provide
employment and educational opportunities for local people as well as creating or stimulating
related service-sector economies.
 On the national scale, tropical countries must integrate existing research on human impacts
on tropical ecosystems into national land use and economic development plans. For tropical
forests to survive, governments must develop realistic scenarios for future deforestation that
take into account what scientists already know about the causes and consequences of
deforestation, including the unintended deforestation that results from road-building,
accidental fire, selective logging, and economic development incentives such as timber
concessions and agricultural subsidies.
 Finally, on the national and international scale, an increasing value in the global marketplace
for products that are certified as sustainably produced or harvested—timber, beef, coffee,
soy—may provide incentives for landowners to adopt more forest-friendly practices, and for
regional and national governments to create and enforce forest-preservation policies. Direct
payments to tropical countries for the ecosystem services that intact tropical forest provide,
particularly for carbon storage to offset greenhouse gas emissions, are likely to become an
important international mechanism for sustaining tropical forests as more countries begin to
seriously tackle the problem of global warming.
19. What is ecological restoration?
Ecological restoration aims to recreate, initiate, or accelerate the recovery of an ecosystem that
has been disturbed. Disturbances are environmental changes that alter ecosystem structure and
function. Common disturbances include logging, damming rivers, intense grazing, hurricanes,
floods, and fires. Restoration activities may be designed to replicate a pre-disturbance
ecosystem or to create a new ecosystem where it had not previously occurred. Restoration
ecology is the scientific study of repairing disturbed ecosystems through human intervention.
Virtually all the worlds' ecosystem types have been the subject of restoration efforts, but
particular attention has been paid to ecosystems most impacted by human activities, such as
wetlands, grasslands/rangelands, riparian areas, and tropical forests.
20. What are some Ecological Restoration Methods used for sustaining an ecosystem?
 Restoration to former natural state
 Rehabilitation into a functional/useful ecosystem (mining sites, landfills, clear-cut forests)
 Remediation after extraction methods, industrial exploitation so there contains no chemical
contaminants (mining, brownfields)
 Replacement with another ecosystem (tree farm for forest)
21. Why should we care about protecting wild species?
It is essential to take actions to protect wildlife from extinction. By doing so, we do not only
ensure their survival, but also the diversity of the ecosystem. As a result, it will help improve
the ecological health of the earth. Listed below are some of the reasons why wildlife protection
is essential.
 Promote Biodiversity; Biodiversity is essential for a healthy and functional ecosystem.
If wildlife is extracted from its natural habitat, the delicate balance of the ecosystem will
be disturbed which will then lead to disastrous results. For instance, there is a wide
diversity of species living in a tropical rain forest. If any species should become extinct,
the food chain will be disrupted affecting all the species. For this reason, promoting
biodiversity is one of the main reasons why we should protect wildlife.
 Beneficial For Humans: One can learn a lot from animals which can benefit the human
race. For instance, a lot of medicines have been derived from the chemicals produced by
animals. These medicines are then used to help cure various health conditions, such as
heart diseases, disorders, and other illnesses. In fact, based on the statistics provided by
the U.S Fish and Wildlife Service, more than 25% of the medicinal prescriptions given
every year contain chemicals from animals. For instance, there are scientists who are
studying venom from the pit viper to cure the symptoms of Melanoma, and the venom
from a tarantula can help fight neurological disorders.
Wildlife protection is essential because if the animal is gone, it will be impossible to
study and learn from them. Unfortunately, a lot of wildlife has disappeared from earth
due to human activities, such as the Bali tiger, Mexican grizzly bear, and the Japanese
wolf.
 Conservation Of Natural Habitat: When we conserve and protect the natural habitat
of wildlife species, we enrich our planet. To do so, we must keep the animals in their
natural place. Conservation of natural habitats will also be beneficial for humans since it
helps keep the essential watersheds intact and ensuring clean, fresh water.Today, there
are now wildlife preservation programs wherein they allow the animals to roam freely in
their natural habitat. Some of these programs also allow the animals to interact with
humans. This is beneficial since it educates the people and raises awareness regarding
the importance of protecting these wildlife species.
22. Which human activities endanger wildlife?
 Species endangered by unsustainable hunting: Overhunting and overfishing have
threatened animal species since aboriginal Europeans, Australians, and Americans
developed effective hunting technology thousands of years ago. The dodo, passenger
pigeon, great auk, and Steller's sea cow were hunted to extinction. Unstainable hunting
and fishing continue to endanger numerous animals worldwide.
 Introduced or invasive species entering the ecosystem: In many places, vulnerable
native species have been decimated by non-native species imported by humans.
Predators like domestic cats and dogs, herbivores like cattle and sheep, diseases, and
broadly-feeding omnivores like pigs have killed, starved, and generally outcompeted
native species after introduction. Some destructive species introductions, like the
importation of mongooses to the Pacific islands to control snakes, are intentional, but
most of the damage caused by exotic species and diseases is unintended. Species living
on islands are especially vulnerable to introduced predators. In one case, the accidental
introduction of the predatory brown tree snake to the Pacific island of Guam in the late
1940s caused a severe decline of native birds. Prior to the introduction of the snake there
were 11 native species of birds on Guam, most of which were abundant. By the mid1980s seven of the native species were extinct or extirpated on Guam, and four more
were critically endangered. The Guam rail, a flightless bird, is now extinct in the wild,
although it survives in captivity and will hopefully be captive-bred and released to a
nearby, snake-free island.
 Habitat destruction: Many species have become extinct or endangered as their natural
habitat has been converted for human land-use purposes. The American ivory-billed
woodpecker, for example, once lived in mature, bottomland hardwood forests and
cypress swamps throughout the southeastern United States. These habitats were heavily
logged and/or converted to agricultural land by the early 1900s. There have been no
reliable sightings of the American ivory-billed woodpecker since the early 1960s, and it
is probably extinct in North America. A related subspecies, the Cuban ivory-billed
woodpecker, is also critically endangered because of habitat loss, as is the closely related
imperial woodpecker of Mexico. Tropical deforestation presents represents the single
greatest threat to endangered species today, though destruction of coastal and shallow
marine habitats associated with anthropogenic global warming may present an even
larger challenges in the future. While there was little net change (-2%) in the total forest
cover of North America between the 1960s and the 1980s, the global area of forested
land decreased by 17% during that period. Conversion of species-rich tropical forests in
Central America, South America, Africa, and the Pacific islands to unforested
agricultural land accounts for most of the decline. (Ironically, tropical soils have such
poor structure and nutrient content that they generally cannot support profitable
agriculture once the forest biomass has been removed.)
23. What is reconciliation ecology and what are its goals?
Reconciliation ecology is the branch of ecology which studies ways to encourage biodiversity in
human-dominated ecosystems. Michael Rosenzweig first articulated the concept in his
book Win-Win Ecology, based on the theory that there is not enough area for all of earth’s
biodiversity to be saved within designated natural preserves. Therefore, humans should increase
biodiversity in human-dominated landscapes. By managing for biodiversity in ways that do not
decrease human utility of the system, it is a "win-win" situation for both human use and native
biodiversity. The science is based in the ecological foundation of human land-use trends and
species-area relationships. It has many benefits beyond protection of biodiversity, and there are
numerous examples of it around the globe. Aspects of reconciliation ecology can already be
found in management legislation, but there are challenges in both public acceptance and
ecological success of reconciliation attempts.Reconciliation ecologists believe increasing
biodiversity within human dominated landscapes will help to save global biodiversity. This is
sometimes preferable to traditional conservation because it does not impair human use of the
landscape and therefore may be more acceptable to stakeholders. However, not only will it
encourage biodiversity in the areas where it takes place, but many scholars cite other benefits of
including biodiversity in human landscapes on both global conservation activities and human
well-being.
 Habitat connectivity benefit: Increasing wildlife habitat in human-dominated systems
not only increases in situ biodiversity, it also aids in conservation of surrounding
protected areas by increasing connectivity between habitat patches. This may be
especially important in agricultural systems where buffers, live fences, and other small
habitat areas can serve as stops between major preserves.
 Educational benefits: Placing importance on native ecosystems and biodiversity within
human landscapes increases human exposure to natural areas,[which has been shown to
increase appreciation of nature. Studies have shown that students who participate
in outdoor education programs show a greater understanding of their environment,
greater willingness to act in order to save the environment, and even a greater
enthusiasm for school and learning. Green spaces have also been shown connect urban
dwellers of all ages with nature, even when dominated by invasive species.
Reconnecting people with nature is especially important for conservation because there
is a tendency for people to use the biodiversity present in the landscape they grew up in
as a point of comparison for future trends.
 Psychological benefits: The results of reconciliation ecology can also improve human
well-being. E. O. Wilson has hypothesized that humans have an innate desire to be close
to nature and numerous studies have linked natural settings to decreased stress and faster
recovery during hospital stays. Many examples of native plants and animals taking
advantage of human dominated landscapes have been unintentional, but may be
enhanced as part of reconciliation ecology. Others are intentional redesigns of human
landscapes to better accommodate native biodiversity. These have been going on for
many hundreds of years including examples within agricultural systems, urban and
suburban systems, marine systems, and even industrial areas.
24. How serious is tropical deforestation, and how can we help sustain tropical forests?
At least half of the world’s terrestrial plant and animal species live
in tropical rain forests. Large areas of tropical forest are burned to make way for cattle
ranches and crops up to 7000 fires a day. They are shrinking at alarming rates.
 How should rangeland resources be used, managed, and sustained? Suppress growth of
invasive species, rotational grazing, reduce soil erosion, replant barren areas, use less
fertilizer and herbicides.
 What problems do parks face, and how should we manage them? Too many visitors,
private owners in parks, money needed to fix, loss of species, pollution – need to buy up
private owners, charge more, and make parking lost off the site.
 How should we establish, design, protect, and manage terrestrial nature reserves?By
passing laws world wide for protection of biodiversity, including ecosystems, species
and populations, promote the long-term survival of the species and other elements of
biodiversity they contain by maintaining natural processes and viable populations and by
excluding threats. To meet these objectives, conservation planning must deal not only
with the location of reserves in relation to natural physical and biological patterns but
also with reserve design, for example the watershed that they will rely on.
25. How do biologists estimate extinction rates, and how do human activities affect these
rates?
It is difficult to measure we have to use the biodiversity methods of sampling and counting species
and the Shannon Weaver method. All species become extinct. Since humans arrived, rate of
extinction has gone up 100 to 1,000 times and by some estimates 10,000 times Conservative
extinction rates 0.01% - 1.0%
Other information to review:
Explain HIPPO or HIPPCO
What is the difference between intrinsic and extrinsic?
How do scientist measure biodiversity?
What do the vales R, H and E mean in regards to biodiversity?
Sample Questions:
Endemic species are
a. usually the dominant species within an ecosystem
b. on the brink of extinction
c. widely distributed, found especially on large continents
d. limited to just one location, such as an island
e. well established and show the least risk of extinction
Wildlife in the Serengeti is currently threatened by
a. plans to build a highway that passes through the park
b. pollution from a nearby coal power plant
c. an invasive fish that has been introduced into the major river that flows through the
park
d. plans to legalize hunting of most of the large animal species in the park
e. an overabundance of elephants
Many of the hot spots for biodiversity are located in areas that are considered to be
a. developing
b. transitional
c. industrialized
d. post-industrial
e. developed
Which of the following statements concerning biodiversity hot spots is correct?
a. they are only found in developed countries
b. there are more hot spots in developed countries than developing countries
c. they tend to be in countries with the highest densities and growth rates
d. they are found in countries with the lowest population density
e. they are found in equal numbers in both temperate and tropical regions
Fragmenting one large park or preserve into many small parks with human habitation in between them
is most likely to lead to which of the following?
a. Increase in gene flow within species
b. increase in the population of top carnivores
c. Decrease in the proportion of edge habitats
d. Stabilization of microclimates
e. Reduction in species diversity
Which of the following statements about exotic species is true?
a. Exotic species are only introduced accidentally, never intentionally.
b. Exotic species are always a threat to biodiversity.
c. Plant species are never exotic species, since plants are not mobile.
d. Overharvesting is a direct cause of the introduction of exotic species.
e. Exotic species are also called alien species.
Which of the following characteristics is most likely to lead to an inbreeding depression?
a. gene flow
b. sexual reproduction
c. ecosystem variability
d. low genetic diversity
e. large population
As the number of Flying Foxes decrease in the Pacific Islands, the trees that grow from the seeds
dispersed by the Flying Fox decreases as well. This is an example
a. k-strategist
b. fragmentation
c. conversion
d. a threatenend species
e. ecological extinction
Which of the following statements about exotic species is true?
a. Exotic species are only introduced accidentally, never intentionally.
b. Exotic species are always a threat to biodiversity.
c. Plant species are never exotic species, since plants are not mobile.
d. Overharvesting is a direct cause of the introduction of exotic species.
e. Exotic species are also called alien species.
Fishing regulations on the size and type of nets used when fishing for tuna help protect endangered
turtle species in the open ocean is an example of ______________________.
What is most significant when determining the diversity of an ecosystem?
What are the causes of the current (sixth) mass extinction?
A species of plant that provides nutritional and/or medicinal benefits for humanity would be referred to
as having ________________ value.