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