Unit 3 - Biology

Evolution

any change in relative frequencies of alleles in a population’s gene pool

Selection pressure

an external force which drives changes in the frequency of traits within a population (disease, predation, etc)

Inheritance

the process by which genetic information is passed from parent to offspring

Fitness

how well an organism can survive and reproduce

Homologous structures

common ancestry, different functions

Analogous structures

different ancestry, same function

Speciation

the evolutionary process by which new, distinct species arise from an ancestral population, caused by isolation

Geographic Isolation

when two populations are separated geographically

Behavioral Isolation

when two populations that were once able to interbreed evolve in courtship rituals/behavior

Cladogram

a diagram that shows how different groups of organisms diverged from common ancestors

Natural selection

the process by which organisms with variations most suited to their environment survive and reproduce

Variation

the differences in characteristics within a population or species

Adaptation

any heritable characteristic that increases an organisms ability to survive and reproduce

Coevolution

when two or more species reciprocally affect each other's evolution

Divergent evolution

two or more related species evolve in different directions from a common ancestor, leading to new species

Convergent evolution

when two unrelated organisms independently evolve similarities when adapting to similar environments

Reproductive isolation

when a species’ gene pool gets split because members stop breeding with other members

Temporal isolation

when two or more species reproduce at different times

Sexual selection

when females select mates based on size, strength, or coloration

Trait

a specific, heritable characteristic or feature of an organism

Vestigial Structures

structures that have lost all/most of their original function through evolution