GCA Environmental Science - Chapter 5: Evolution and Community Ecology

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5.1 Evolution 5.2 Species Interactions 5.3 Ecological Communities 5.4 Community Stability

natural selection

process by which individuals that are better suited to their environment survive and reproduce most successfully

evolution

generation-to-generation change in the proportion of different inherited genes in a population that account for all of the changes that have transformed life over an immense time

survival of the fittest

a natural process resulting in the evolution of organisms best adapted to the environment

threatened species

a species that could become endangered in the near future

endangered species

a species whose numbers are so small that the species is at risk of extinction

extinct species

a species that was once present on Earth but has died out

predator

animal that hunts and eats other animals

prey

animal hunted or caught for food

extirpated

species that have disappeared from an area, but still exist elsewhere

habitat loss

the process in which natural habitat is rendered functionally unable to support the species present; leading cause of species decline

adaptation

inherited characteristic that increases an organism's chance of survival

structural adaptation

a physical feature of an organism's body having a specific function that contributes to the survival of the organism

behavioral adaptation

an inherited behavior that helps an organism survive

mimicry

an adaptation that allows an animal to protect itself by looking like another kind of animal or like a plant

reflex

an automatic instinctive unlearned reaction to a stimulus, an automatic response that occurs very rapidly and without conscious control (playing dead)

instinct

a complex behavior that is rigidly patterned throughout a species and is unlearned (migration)

extinct

no longer in existence

biodiversity

the number of different species in a given area

symbiosis

relationship in which two species live closely together over a long period of time

parasitism

symbiotic relationship in which one organism lives in or on another organism (the host) and consequently harms it

mutualism

symbiotic relationship in which both species benefit from the relationship

commensalism

symbiotic relationship in which one member of the association benefits and the other is neither helped nor harmed

food chain

series of steps in an ecosystem in which organisms transfer energy by eating and being eaten

food web

consists of the many overlapping food chains in an ecosystem

producer

an organism that makes its own food

consumer

an organism that obtains energy by feeding on other organisms

herbivore

organism that obtains energy by eating only plants

secondary consumer

An organism that eats primary consumers

carnivore

organism that obtains energy by eating animals

omnivore

organism that obtains energy by eating both plants and animals

tertiary consumer

An organism that eats secondary consumers

scavenger

a detritivore that gets its energy by feeding on refuse and other decaying organic matter

decomposer

organism that breaks down and obtains energy from dead organic matter

trophic level

Steps on a food/biomass pyramid that are defined by organisms within a community that are the same distance from the primary producers in a food web

energy pyramid

diagram that shows the energy available to each trophic level in an ecosystem; 10% is passed on to upper levels, the rest is lost as heat

ecological succession

The gradual and orderly process of change in an ecosystem brought about by the progressive replacement of one community by another until a stable climax is established

primary succession

an ecological succession that begins in a an area where no biotic community previously existed

pioneer species

first species to populate an area during primary succession

climax community

The last or final stage of succession in a community which is in equilibrium with its environment

secondary succession

Sequence of community changes that take place after a community is disrupted by natural disasters or human actions

sustainability

The concept of using the earth's resources in such they provide for people's needs in the present without diminishing ability to provide for future generations

gene

a sequence of DNA that codes for a particular trait

genetic drift

biological evolution that occurs by chance

fitness

describes how reproductively successful an organism is in its environment

artificial selection

process of selection conducted under human direction

speciation

process by which new species are generated

tolerance

the ability to survive and reproduce under changing environmental conditions

resource partitioning

species divide the resource they use in common by specializing in different ways

coevolution

two species evolve in response to changes in each other

chemosynthesis

primary producers use energy stored in the bonds of hydrogen sulfide to convert carbon dioxide and water into sugars (energy from chemicals on ocean floor)

detritivores

cycle the nutrients of nonliving organic matter, including leaf litter, waste products, and the dead bodies of other community members

keystone species

a species with a strong or wide-reaching impact on a community

invasive species

a nonnative organism that spreads widely in a community

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