BIOL 112 Lab 2

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Evidence for Evolution

Four unifying themes of Biology:

1. Cell Theory
2. Gene Theory
3. Theory of Inheritance
4. Theory of Evolution
   1. Species change over time
   2. Species are related through descent from a common ancestor
   3. Biological change is driven by observable forces

Evidence supporting Evolution

• Fossil Record
• Biogeography
• Homology and Analogy
• Vestigial Traits
• Developmental Similarities
• Molecular Genetics (similarities/differences in proteins)
• Observation of Evolutionary Change

Describing Relationships

Phylogenetic trees have one of three forms:

1. Monophyletic: (single ancestor) includes the entire subtree (all descendants) of a common ancestor. Also called a clade.
2. Polyphyletic: (multiple ancestor) many subtrees that do not show any relation to a common ancestor.
3. Paraphyletic: (to one side of ancestor) similar to monophyletic, but does not include all descendants of a common ancestor.

Biogeography

Biodiversity over a geographical area.

Populations isolated into geographical areas by "sudden" incursions called vicariances

Homology

Related species will share common inheritable traits. Some traits might be different due to divergent evolution.

All of these mammals have similar forelimb structures derived from the same bones of a mammalian common ancestor:

bat (wing), whale (flipper), human (arm), horse (leg)

Also gives rise to vestigial (vanishing) structures: whales' ancestor had legs, but those disappeared after getting in the water.

Analogy

Unrelated species develop similar solutions and adaptations to similar environmental conditions. This is called convergent evolution

Dolphins and sharks have streamlined bodies, dorsal and pectoral fins, and powerful tails.