Comparative AnatomySimilarities in the basic pattern of anatomy is evidence ofinheritance from a common ancestor:i) Homologous Structuresii) Analogous Structuresiii) Vestigial Structures
Comparative Anatomyi) Homologous Structures:• Body parts of different species with similar structuresbut different functions.• Evidence of close evolutionary relationship (recentcommon ancestor).
Comparative Anatomy Homologous Structures
Comparative Anatomyii) Analogous Structures:• Body parts of different species with similar functionsbut different structures.• No evolutionary relationship. Australian squirrel glider North American chipmunk
Comparative AnatomyThough this marsupial and placental mammal look verysimilar, they are distantly related. Their methods ofgestation and birth are analogous. Australian squirrel glider North American chipmunk Marsupial Placental mammal
Comparative Anatomy Analogous Structures The coloured bones are homologous. The thin membrane of an insects wing is analogous to feathers or leathery flesh.
Comparative Anatomyiii) Vestigial Structures:• Structures of little or no use.• These are remnants of structures in an ancestralspecies that had a use for them.Humans no longer have an inner eyelid - a structure similar to the one on cats -but we still have the remnants of one (dont worry, shes not hurting the cat).
Comparative Anatomy Vestigial Structures on Humans plica semilunaris + goosebumps
Comparative Anatomyiii) Vestigial Structures: Some whale fossils have hind leg bones.
Comparative Anatomyiii) Vestigial Structures: The cave fish (on the right) is blind, yet it still has eyes.