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Evolution Natural Selection and Evidence Ch. 15.1 Definition •Evolution = the change in populations over time Evidence •How do we know that evolution happened? –Adaptations –Fossils –Anatomy –Embryology –Biochemistry Evidence •Fossils –Show changes through time –Not complete, but gives the overall picture Evidence •Anatomy •Homologous structures –Similarity in form of major body parts –Indicates that the species had a common ancestor Evidence • Homologous structures See p. 409 in book Evidence •Vestigial structures –Body structure that has no function –Probably was useful in an ancestor –Ex. Appendix in humans, wings in ostrich, leg bones in snakes Evidence •Embryology –Study of the earliest stages of growth –Can see similarities in embryos that you don’t see in adult forms –Suggests they evolved from a common ancestor Evidence •Embryology Evidence •Embryology Evidence •Embryology Evidence •Embryology Evidence •Biochemistry –All living things share same biochemistry –Closely related organisms have more similar DNA sequences –Can use comparisons of DNA to determine relationships between species Evidence •Can see it happening in species with short generation times –Bacteria –Insects –Yeast
