A.4.1 - Evolution and speciation

Three types of evidence for evolution

• Molecular evidence from amino acid sequences and genetic data

• Morphological evidence from homologous structures revealing common ancestors

• Experimental evidence from selective breeding

Homologous vs. analogous structures

Homologous: evolved from a common ancestor, similar anatomy, may have different functions (i.e. pentadactyl limbs in humans, birds, and bats)

Analogous: serve the same function, but evolved from different ancestors and can have dissimilar anatomy (i.e wings in insects vs. birds) 

Evolution def.

Cumulative change in the heritable characteristics of a population

Speciation split

Evolution to the point where a new species arises

Common ancestor shown in early embronic development of humans

Slits on the side of the neck similar to gills

Artificial selection example

Corn/maize descended from Teosinte, an ancient wild grass, by selective breeding (farmers only planting seeds of the grass with the most desirable traits)