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23 terms

Evolution

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evolution
change in a kind of organism over time; process by which modern organisms have descended from ancient organisms
natural selection
the principle that, among the range of inherited trait variations, those that lead to increased reproduction and survival will most likely be passed on to succeeding generations; also called "survival of the fittest"
homologous structures
structures that have different mature forms but develop from the same embryonic tissues
vestigial structures
remnant of a structure that may have had an important function in a species' ancestors, but has no clear function in the modern species
allele frequency
the number of times an allele occurs in a gene pool, compared to the total number of alleles in that pool for the same gene
gene pool
all the genes, including all the different alleles for each gene, that are present in a population at any one time
founder effect
genetic drift that occurs when a few individuals become isolated from a larger population, with the result that the new population's gene pool is not reflective of the original population.
Hardy-Weinberg Principle
allele frequencies in a population will remain constant unless one or more factors cause the frequencies to change
species
group of similar organisms that can breed and produce fertile offspring
behavioral isolation
form of reproductive isolation in which two populations have differences in courtship rituals or other types of behavior that prevent them from interbreeding
temporal isolation
form of reproductive isolation in which two populations reproduce at different times
geographic isolation
form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water
extinct
species that no longer exist
convergent evolution
when two or more species NOT descended from a common ancestor develop similar traits as they adapt to the same type of environment
adaptive radiation
process by which a single species or small group of species evolves into several different forms that live in different ways; rapid growth in the diversity of a small group of organisms
gradualism
a model of evolution in which gradual change over a long period of time leads to biological diversity
punctuated equilibrium
evolutionary model suggesting species often diverge in spurts of relatively rapid change, followed by long periods of little change
directional selection
form of natural selection in which the entire curve moves; occurs when individuals at one end of a distribution curve have higher fitness than individuals in the middle or at the other end of the curve
stabilizing selection
form of natural selection by which the center of the curve remains in its current position; occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end
disruptive selection
form of natural selection in which a single curve splits into two; occurs when individuals at the upper and lower ends of a distribution curve have higher fitness than individuals near the middle
adaptation
inherited characteristic that increases an organism's chance of survival
fitness
how well an organism can survive and reproduce in its environment
speciation
the formation of new species as a result of evolution