Unit 2 · The Living World: Biodiversity

Levels of biodiversity ● (core concept) — Biodiversity in an ecosystem includes genetic, species, and habitat diversity.

Genetic diversity and population bottleneck ● (core concept) — The more genetically diverse a population is, the better it can respond to environmental stressors. A population bottleneck — a sharp reduction in population size — can lead to a loss of genetic diversity.

Species diversity and ecosystem recovery ● (core concept) — Ecosystems that have a larger number of species are more likely to recover from disruptions.

Habitat loss and species loss ● (core concept) — 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 ● (core concept) — Species richness refers to the number of different species found in an ecosystem.

Ecosystem services (four categories) ● (core concept) — The four categories of ecosystem services are provisioning, regulating, cultural, and supporting services.

Human disruption of ecosystem services ● (core concept) — Anthropogenic (human-caused) activities can disrupt ecosystem services, potentially resulting in economic and ecological consequences.

Island biogeography ● (core concept) — Island biogeography is the study of the ecological relationships and distribution of organisms on islands, and of these organisms' community structures.

Island colonization ● (core concept) — Islands have been colonized in the past by new species arriving from elsewhere.

Island specialists and invasive generalists ● (core concept) — 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 when invasive species, typically generalists, are introduced and outcompete them.

Ecological tolerance ● (core concept) — 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. It can apply to individuals and to species.

Natural disruptions vs. human disruptions ● (core concept) — Natural disruptions to ecosystems have environmental consequences that may, for a given occurrence, be as great as, or greater than, many human-made disruptions.

Time scales of Earth processes ● (core concept) — Earth system processes operate on a range of scales in terms of time. Processes can be periodic (regularly repeating), episodic (occasional events), or random.

Climate and sea-level change over geologic time ● (core concept) — Earth's climate has changed over geological time for many reasons, and sea level has varied significantly as a result of changes in the amount of glacial ice on Earth.

Environmental upheaval and habitat change ● (core concept) — Major environmental change or upheaval commonly results in large swathes of habitat changes.

Wildlife migration ● (core concept) — Wildlife engages in both short- and long-term migration for a variety of reasons, including natural disruptions.

Natural selection and adaptation ● (core concept) — Natural selection acts on heritable traits, causing populations to adapt to their environment over generations via incremental changes at the genetic level.

Responses to environmental change ● (core concept) — Environmental changes, either sudden or gradual, may threaten a species' survival, requiring individuals to alter behaviors, move, or perish.

Primary and secondary succession ● (core concept) — There are two main types of ecological succession: primary succession, which begins in an area with no previous life and no soil (e.g., bare rock), and secondary succession, which occurs in a previously occupied area where soil remains after a disturbance.

Keystone species ● (core concept) — A keystone species is a species whose activities have a particularly significant role in determining community structure.

Indicator species ● (core concept) — 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 species ● (core concept) — 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 and ecosystem characteristics ● (core concept) — Succession in a disturbed ecosystem will affect the total biomass, species richness, and net productivity over time.