Evolution Latest Update Already Graded A

Evolution Latest Update Already Graded A Theory of Evolution the best scientific explanation for both the unity and diversity of life; proposed by Charles Darwin Charles Darwin Father of Evolution evolution change in allele frequency over time; process by which modern organisms have descended from ancient organisms (decent with modification) genetic equilibrium situation in which allele frequencies remain constant; no evolution occuring natural selection natures way of selecting the best a particular environment; also called survival of the fittest diversity all of the different species on Earth variation the differences within a single species species group of similar organisms capable of interbreeding and producing fertile offspring speciation formation of new species common ancestry a group of organisms share common descent if they have a common ancestor biogeography the study of the distribution of species and ecosystems in geographic space and through geological time; evidence of common ancestry fossil record the geological record of organisms on earth that have been preserved in the rock in a chronological order (oldest on bottom); evidence of common ancestry embryology the study of embryos; evidence of common ancestry molecular homology similar amino acid sequences (DNA) among different species from a common ancestor; evidence of common ancestry homologous structures structures that have different mature forms in different organisms but develop from the same embryonic tissues; evidence of common ancestry analogous structures is a trait or an organ that appears similar in two unrelated organisms vestigial structure a structure that an organism has that is no longer useful to it, but that they have this structure because a common ancestor to that organism found it useful fitness ability of an organism to survive and reproduce in its environment adaptation inherited characteristic that increases an organism's chance of survival mimicry the similarity of one species to another which protects one or both camouflage when an organism blends in with its environment for protection against predators cladogram diagram that shows the evolutionary relationships among a group of organisms derived characteristics characteristic that appears in recent parts of a lineage, but not in its older members divergent evolution (adaptive radiation) process by which a single species or small group of species evolves into several different forms that live in different ways convergent evolution process by which unrelated organisms independently evolve similarities when adapting to similar environments coevolution the evolution of two or more interdependent species, each adapting to changes in the other gradualism when speciation occurs over long periods of time rather than by sudden major changes punctuated equilibrium pattern of evolution in which long stable periods (stasis) are interrupted by brief periods of rapid change extinction disappearance of a species from all parts of its geographical range gene pool the sum of all the genes in an interbreeding population allele frequency number of times an allele occurs in a gene pool inherited vs. acquired traits characteristic passed on via genetic material vs. physical characteristic that is not inherited but may be an effect of the environment single-gene trait trait controlled by a single gene (ex: widow's peak in humans) polygenic trait trait controlled by two or more genes (ex: skin color of humans) stabilizing selection form of natural selection that occurs when individuals near the center of a distribution curve have higher fitness than individuals at either end directional selection form of natural selection that 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 disruptive selection form of natural selection that occurs when individuals at both ends of a distribution curve have higher fitness than individuals near the middle reproductive isolation the inability of a species to breed successfully with related species due to geographical, behavioral, physiological, or genetic barriers or differences 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 geographic isolation form of reproductive isolation in which two populations are separated physically by geographic barriers such as rivers, mountains, or stretches of water temporal isolation form of reproductive isolation that occurs when members of two species occupy similar habitats, but breed at different times natural resistance ex: bacterial resistance to antibiotics or insects resistant to pesticides/insecticides gene flow is the transfer of alleles or genes from one population to another genetic drift change in allele frequencies of a population due to chance or random events rather than by natural selection mutation a random change in the DNA that can possibly be beneficial and can produce genetic variation in a species crossing over also called gene shuffling or genetic recombination; produces genetic variation in a species