Evidence for evolution
Comparative Anatomy
Homology: A similar physiological structure inherited from a common ancestor. Does not necessarily have the same function!
Analogy: A similar physiological structure due to convergent evolution. Looks similar and has a similar function!
Homology and Analogy
(Tetrapod: Animal with four limbs)
Homologous Structures
Homology and Evolution
Homologies are everywhere…Leaves of an oak tree and of a gingko tree.
The wings of a dragonfly and the wings of a butterfly.
And are not always obvious…
Each is a modification of the basic incisor tooth structure. Over time, evolution adapted each of these animals' incisors to perform different functions. They are homologous structures, inherited from a common ancestor with incisor teeth.
And are not only structural…
Analogous Structures
How do analogies evolve…What happens if the
long red flowers disappear?
So… Homology or Analogy?
Criteria for homologies…Same basic structure
Same relationship to other features
Same development
Using homologies to reconstruct relationships…
Structures that serve no function in a living organism.
Vestigial Features and Anatomical Oddities
Are these vestigial structures?
Vestigial Features and Anatomical Oddities
Are these vestigial structures?
Vestigial Features and Anatomical Oddities
What about the pilomotor reflex?
Vestigial Features and Anatomical Oddities