ANHB1101 Lecture Notes - Lecture 3: Comparative Anatomy, Common Descent, Pentadactyl
5 Sep 2018
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Similarities and differences in anatomy of different species. Features in common as they stemmed from a common ancestor with these features. Differences due to different environments and favouring of desirable adaptations. Homology the same organ in different organisms under every variety of form and function (owen). Phylogenetic constraint no vertebrates have 6 limbs. Variations are based on what was previously there. Atavistic features - atavism is an evolutionary throwback, such as traits reappearing which had disappeared generations before. Some horses born with an extra toe (evidence for evolution and common ancestry). Analogous features similar features evolve independently through similar environmental pressures in different geographical locations or from different common ancestors. Homology vertebrates limbs are homologous structures as all are composed of similar bones inherited from a recent common ancestor. Analogy - wings on bats, butterflies and birds evolved independently, not from a recent common ancestor. But they have a similar function of flight and so are analogous.
