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GCA Environmental Science - Chapter 5: Evolution and Community Ecology

5.1 Evolution 5.2 Species Interactions 5.3 Ecological Communities 5.4 Community Stability
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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