BI SC 002 Lecture Notes - Lecture 32: Vestigiality
Document Summary
A vestigial structure has lost its function but is homologous to a functional structure in another species: mole. Small bones where they would have had hind limbs many years ago: modern whale. Vestigial hind limbs in some snake species and pelvises in whales: evidence of these organisms" ancestors. Anatomical structures are analogous if they are superficially similar but did not derive form a common ancestor. Neither of these cave animals have pigment or eyes. Examples: salamander, cave crayfish, dolphins and sharks. Similar because beneficial for their living environment. But completely different: one is a mammal, one is a fish. These similarities arose by convergent evolution: produces similar structures in organisms that do not share the same lineage. Lack of pigment arose independently in each of these cave animals. Anatomical similarities are often most obvious in embryos. Notice how much more similar human and chimpanzee skull structure is in fetuses: compared to in adults. Bird wings are modified: arms, claws.
