Ecosystems and Biodiversity

Important Case Studies and Legislation

  • Colorado River Case Study - expect to see an FRQ about this on your exam

  • Distribution of Water on the Planet

  • Clean Water Act (CWA)

  • Safe Drinking Water Act (SDWA)


  • A biome contains characteristic communities of plants and animals that result from, and are adapted to, its climate.

  • Major terrestrial biomes include taiga, temperate rainforests, temperate seasonal forests, tropical rainforests, shrubland, temperate grassland, savanna, desert, and tundra.

    1. Know the abiotic and biotic factors that determine a particular biome.

  • The global distribution of nonmineral terrestrial natural resources, such as water and trees for lumber, varies because of some combination of climate, geography, latitude and altitude, nutrient availability, and soil.

  • The worldwide distribution of biomes is dynamic; the distribution has changed in the past and may again shift as a result of global climate changes.

    • If the distribution of biomes shifts, how might that affect the organisms that live in that biome?

Ponds vs. Lakes vs. Streams vs. Rivers

    • These are a vital source of drinking water

      1. Which has the most moving water? Which has the least?

      2. What types of organisms will live in the different areas of these bodies of water?

      3. What health problems can arise due to dirty or contaminated water?

      4. What are some of the things we are doing to combat the loss of fresh water?

Estuaries vs. Intertidal vs Coral Reefs

    • All are highly productive

      1. Which is located in nutrient-rich water?

      2. Which is located in nutrient-poor water?

      3. Which has the clearest water?

      4. Why are these areas called nurseries?

    • Most red light is absorbed in the upper 1m of water, and blue light only penetrates deeper than 100m in the clearest water. This affects photosynthesis in aquatic ecosystems, whose photosynthesizers have adapted mechanisms to address the lack of visible light

      1. What are the zones of the ocean?

      2. Which gets the most light?

      3. Which gets the least?

      4. Why is this important?

    • Algae in marine biomes supply a large portion of the Earth's oxygen and also take in carbon dioxide from the atmosphere

      1. Why is this important (especially the carbon dioxide absorption)?

    • The global distribution of nonmineral natural resources, such as different types of fish, varies because of some combination of salinity, depth, turbidity, nutrient availability, and temperature

Conservation Biology

  • Human survival depends on developing practices that will achieve sustainable systems. A suitable combination of conservation and development is required. The management of resources is essential. Understanding the role of cultural, social, and economic factors is vital to the development of solutions.

    • How should we manage and sustain parks and natural reserves?

    • What is the ecosystem approach to sustaining biodiversity?

    • Will restoration encourage further destruction and what can you do?


  • Biodiversity in an ecosystem includes genetic, species, and habitat diversity.

  • The more genetically diverse a population is, the better it can respond to environmental stressors. Additionally, a population bottleneck can lead to a loss of genetic diversity.

  • Ecosystems that have a larger number of species are more likely to recover from disruptions.

  • Loss of habitat leads to a loss of specialist species, followed by a loss of generalist species. It also leads to reduced numbers of species that have large territorial requirements.

  • Species richness refers to the number of different species found in an ecosystem.

    1. Why is biodiversity important?

    2. What does it mean for an ecosystem to be "resilient"?

    3. Why would an ecosystem with a higher species richness be more resilient?

    4. Which species will die first when an ecosystem is changed or destroyed?

    5. How does the conservation of biological diversity involve an understanding of the intricate relationships among species and between species and their environments?

    6. What are the ecological functions of biological diversity?

    7. What major problems are associated with biological diversity and what impact does human activity have?

Evolution and Natural Selection

  • Organisms adapt to their environment over time, both in short- and long-term scales, via incremental changes at the genetic level.

  • Environmental changes, either sudden or gradual, may threaten a species’ survival, requiring individuals to alter behaviors, move, or perish.

    1. Why is it important for a species to have a high genetic diversity?

    2. What can happen if a species loses too much genetic diversity?

Island Biogeography

  • Island biogeography is the study of the ecological relationships and distribution of organisms on islands, and of these organisms’ community structures.

  • Islands have been colonized in the past by new species arriving from elsewhere.

  • Many island species have evolved to be specialists versus generalists because of the limited resources, such as food and territory, on most islands. The long-term survival of specialists may be jeopardized if and when invasive species, typically generalists, are introduced and outcompete the specialists.

    1. Why is island biogeography important?

    2. Which would have more UNIQUE species: an island close to the mainland or an island far away from the mainland?

    3. Which islands are examples of evolution due to an island's location?

    4. Why are island species unlikely to be successful in the wild if they were transported to the mainland?


  • Ecological tolerance refers to the range of conditions, such as temperature, salinity, flow rate, and sunlight that an organism can endure before injury or death results.

  • Ecological tolerance can apply to individuals and to species.

    1. What abiotic factors tend to influence the ecological tolerance of a species? Biotic?

    2. What limits the growth of populations?

    3. How do communities and ecosystems respond to changing environmental conditions?

Ecosystem Disruptions

  • Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions.

  • Earth system processes operate on a range of scales in terms of time. Processes can be periodic, episodic, or random.

  • Earth’s climate has changed over geological time for many reasons.

  • Sea level has varied significantly as a result of changes in the amount of glacial ice on Earth over geological time.

  • Major environmental change or upheaval commonly results in large swathes of habitat changes.

  • Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions.

    1. Know some examples of ecosystem disruptions and their effects.

    2. What can an organism do if their habitat changes? HINT: Adapt, die, move - Know examples of each.


  • There are two main types of ecological succession: primary and secondary succession.

  • A keystone species in an ecosystem is a species whose activities have a particularly significant role in determining community structure.

  • An indicator species is a plant or animal that, by its presence, abundance, scarcity, or chemical composition, demonstrates that some distinctive aspect of the character or quality of an ecosystem is present.

  • Pioneer members of an early successional species commonly move into unoccupied habitat and over time adapt to its particular conditions, which may result in the origin of new species.

  • Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.

    1. What is the differences in primary and secondary succession?

    2. Which is more common?

    3. Which species arrive first in succession? Last?

    4. What are differences in these species?

    5. Why are keystone species important?

    6. Know some examples of keystone species.

    7. What are indicator species?

    8. Know some examples of indicator species/phyla.

    9. What is the difference between an indicator and keystone species?

    10. How do species replace one another in ecological succession?

Relationships Between Species

  • In a predator-prey relationship, the predator is an organism that eats another organism (the prey).

  • Symbiosis is a close and long-term interaction between two species in an ecosystem. Types of symbiosis include mutualism, commensalism, and parasitism.

  • Competition can occur within or between species in an ecosystem where there are limited resources. Resource partitioning— using the resources in different ways, places, or at different times—can reduce the negative impact of competition on survival.

    1. How do species interact?

    2. Be able to describe mutualism, commensalism, and parasitism.

    3. Know examples of each of the above.

    4. Why is competition important?

    5. Why would an organism not utilize its entire niche?

Biodiversity Loss

  • HIPPCO (habitat destruction, invasive species, population growth, pollution, climate change, and over exploitation) describes the main factors leading to a decrease in biodiversity.

  • Habitat fragmentation occurs when large habitats are broken into smaller, isolated areas. Causes of habitat fragmentation include the construction of roads and pipelines, clearing for agriculture or development, and logging.

  • The scale of habitat fragmentation that has an adverse effect on the inhabitants of a given ecosystem will vary from species to species within that ecosystem.

  • Global climate change can cause habitat loss via changes in temperature, precipitation, and sea level rise.

  • Some organisms have been somewhat or completely domesticated and are now managed for economic returns, such as honeybee colonies and domestic livestock. This domestication can have a negative impact on the biodiversity of that organism.

  • Some ways humans can mitigate the impact of loss of biodiversity include creating protected areas, use of habitat corridors, promoting sustainable land use practices, and restoring lost habitats.

    1. Memorize HIPPCO - not just the acronym, but what each stands for.

    2. What are some problems with habitat fragmentation? Why does it disproportionately affect larger animals?

    3. How can climate change affect a species' range.

    4. What are some benefits of domesticating a species? Drawbacks?

    5. What can we do to reduce/mitigate the impacts of biodiversity loss? Can all strategies be used with all species? Why or why not?

    6. Should we protect certain species and not others?

Invasive Species

  • Invasive species are species that can live, and sometimes thrive, outside of their normal habitat. Invasive species can sometimes be beneficial, but they are considered invasive when they threaten native species.

  • Invasive species are often generalist, r-selected species and therefore may outcompete native species for resources.

  • Invasive species can be controlled through a variety of human interventions.

    1. How do invasive species get to their new habitat?

    2. What is the difference between a nonnative species and an invasive species?

    3. Is a nonnative species ALWAYS an invasive species?

    4. What are typical characteristics of invasive species?

    5. How can we reduce the impacts of invasive species?

Endangered Species

  • A variety of factors can lead to a species becoming threatened with extinction, such as being extensively hunted, having limited diet, being outcompeted by invasive species, or having specific and limited habitat requirements.

  • Not all species will be in danger of extinction when exposed to the same changes in their ecosystem. Species that are able to adapt to changes in their environment or that are able to move to a new environment are less likely to face extinction.

  • Selective pressures are any factors that change the behaviors and fitness of organisms within an environment.

  • Species in a given ecosystem compete for resources like territory, food, mates, and habitat, and this competition may lead to endangerment or extinction.

  • Strategies to protect animal populations include criminalizing poaching, protecting animal habitats, and legislation.

    1. What is an endangered species?

    2. Which species are MOST likely to become endangered? Why?

    3. What can we do to protect endangered species? Describe some SPECIFIC examples. (NOTE: "ban whatever" or "protect whatever" is not specific enough)

    4. Do these strategies always work? Why or why not?