Evidence for macroevolution Strongest Fossil Record order of

Evidence for macroevolution Strongest = Fossil Record • order of fossils in sediments • oldest at bottom • date with radioisotopes

Fossil Record Find successive change in groups of organisms: "missing links" • whale legs & shape

Fossil Record Find successive change in groups of organisms: "missing links" • whales • horse size

Fossil Record Find successive changes: "missing links" • whale legs & shape • horse size • hominid cranium

Evidence for macroevolution DNA: many genes are so similar that they must have diverged from a common ancestor: Align genes, count diffs

Evidence for macroevolution DNA: many genes are so similar that they must have diverged from a common ancestor Align genes, count diffs # changes says when 2 spp. split

Molecular clocks Align genes, count diffs # changes tells when 2 spp. split Calibrate with fossil record

Mitochondrial DNA traces Mom • only comes from mom & doesn’t recombine • says we split ~ 170, 000 years ago Y chromosome traces Dad • only comes from dad & doesn’t recombine • Says we entered Europe ~ 50, 000 years ago

Evidence for macroevolution Fossil record DNA Comparative anatomy: same bones derived from common ancestor: shape & function has changed

Evidence for macroevolution Fossil record DNA Comparative anatomy: same bones derived from common ancestor: shape & function changed Vestigial structures: non-functional left-overs

Evidence for macroevolution Fossils DNA Comparative anatomy Embryos retrace evolution as they develop

Embryos retrace phylogeny Embryos retrace evolution as they develop

Embryos retrace phylogeny Embryos retrace evolution as they develop Close spp look alike longer

Convergent evolution similar selection results in organisms that look alike e. g. desert plants: American cacti & African euphorbs look alike but unrelated

Convergent evolution similar selection -> organisms look alike e. g. Australian marsupials resemble American placental mammals

Convergent evolution similar selection -> organisms look alike e. g. Australian marsupials resemble American placental Mammals Fill same niche: role in nature

Analogy vs homology Analogous: look alike but different origin Bird vs insect wings

Analogy vs homology Analogous: look alike but different origin Bird vs insect wings fins vs flippers

Analogy vs homology Analogous: look alike but diff origin • Bird vs insect wings • fins vs flippers Homologous: look different, same origin

Pace of evolution Some plants evolve rapidly Mammals evolve slowly Starfish evolve very slowly

Pace of evolution Gradualism: gradual evolution Large populations Slow change in selection

Pace of evolution Gradualism: gradual evolution Large populations Slow change in selection Punctuated equilibria: evolve in spurts

Pace of evolution Punctuated equilibria: evolve in spurts small populations Genetic drift alters gene pool Rapidly adapt then reach equilibrium

Pace of evolution Mass extinctions: O 2 poisoning 2 b. y. a. killed most bacteria

Mass extinctions O 2 poisoning 2 b. y. a. killed most bacteria 96% of species died at end of Permian Asteroid 65 m. y. a. killed dinosaurs

Mass extinctions O 2 poisoning 2 b. y. a. killed most bacteria 96% of species died at end of Permian: asteroid? Asteroid 65 m. y. a. killed dinosaurs Man is causing another mass extinction! Enable evolution of new spp!

Mass extinctions Enable evolution of new spp! Formerly occupied niches become available major factor in success of mammals