BIOL 123 Lecture Notes - Lecture 25: Karl Ernst Von Baer, Embryology, Convergent Evolution
Document Summary
Fossils provide evidence of evolutionary change over time. Fossils of modern whales illustrate stages in the evolution of an aquatic species from land-dwelling ancestors. New species evolved from and replaced previous species. Comparative anatomy gives evidence of descent with modification. Similarities in bodies of modern organisms suggest descent from a common ancestor. Homologous structures provide evidence of common ancestry. Homologous structures = internally similar structures; same evolutionary origin despite differences in current function or appearance. Examples: pterodactyl, bird, and bat; dolphin and seal; dog and sheep; Functionless structures are inherited from ancestors. human and shrew have same bone arrangements in forelimbs. Vestigial structures = structures that serve no purpose or apparent function. Examples: molar teeth in vampire bats (does not chew, drinks blood); pelvic bones in whales and snakes. Some anatomical similarities result from evolution in similar environments. Convergent evolution = in which natural selection causes non-homologous.
