Unit 2: The Living World: Biodiversity
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2.1 Introduction to Biodiversity
ERT-2.A—Explain levels of biodiversity and their importance to ecosystems
Explain levels of biodiversity and their importance to ecosystems. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.2 Ecosystem Services
ERT-2.B—Describe ecosystem services
Describe ecosystem services. • There are four categories of ecosystem services: provisioning, regulating, cultural, and supporting. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
ERT-2.C—Describe the results of human disruptions to ecosystem services
Describe the results of human disruptions to ecosystem services. • Anthropogenic activities can disrupt ecosystem services, potentially resulting in economic and ecological consequences. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.3 Island Biogeography
ERT-2.D—Describe island biogeography
Describe 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
ERT-2.E—Describe the role of island biogeography in evolution
Describe the role of island biogeography in evolution. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.4 Ecological Tolerance
ERT-2.F—Describe ecological tolerance
Describe ecological tolerance. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.5 Natural Disruptions to Ecosystems
ERT-2.G—Explain how natural disruptions, both short- and long-term, impact an ecosystem
Explain how natural disruptions, both short- and long-term, impact an ecosystem. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.6 Adaptations
ERT-2.H—Describe how organisms adapt to their environment
Describe how organisms adapt to their environment. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
2.7 Ecological Succession
ERT-2.I—Describe ecological succession
Describe ecological succession. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.
ERT-2.J—Describe the effect of ecological succession on ecosystems
Describe the effect of ecological succession on ecosystems. • 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. • Enduring understanding ERT-2: Ecosystems have structure and diversity that change over time.