Evolution and Natural Selection equilibrium punctuated precambrian radiation adaptive Darwin change over time artificial selection stromatolites mutations evolution vestigial no longer used dog breeds Hardy-Weinburg disruptive selection speciation polygenic trait equilibrium genetic new species from many phenotypes leads to speciation absolute dating natural selection the fittest survival of endosymbiotic theory eukaryotes explains species evolve together coevolution gene shuffling directional selection stabilizing selection gene pool behavioral isolation all genes in a population shifts to extreme whole population in population reduces variety mating ritutals characteristics acquired index fossil Lamarck Darwin selection natural Era Mesozoic Miller & Urey geographic isolation temporal isolation homologous structures single gene trait rivers, mountains evidence for evolution mating seasons two phenotypes relative dating period Quaternary Hutton geologic processes Lyell age of earth Wallace ecological competition founder effect random mating HMS Beagle