Bio | Evidence of Evolution

Fossil Record: How does it show evolution?

Shows transitional forms and a clear sequence of change in organisms over time (e.g., horse size/toe reduction).

Embryology: How does it support common ancestry?

Early embryos of different vertebrates show striking similarities (e.g., gill slits, tails) suggesting a shared developmental plan.

Homologous Structures (Comparative Anatomy): Definition & Evidence?

Structures with the same underlying bone structure but different functions; evidence of a common ancestor.

Vestigial Structures: How do they support evolution?

They are useless remnants of structures that served a purpose in an ancestor, showing descent with modification (e.g., whale pelvis, human tailbone).

Molecular Biology (Cytochrome C): How does it show relatedness?

Fewer differences in DNA or protein sequences (e.g., amino acids) means a more recent common ancestor (closer evolutionary relationship).

Evolution in Action (Antibiotic Resistance): What is the selective pressure and the result?

Antibiotic is the selective pressure; results in rapid evolution through natural selection on random mutations.

Cladogram: What does this diagram show and what defines a branch point?

• Shows evolutionary relationships and common ancestry

• Each branch point represents a shared derived characteristic (a new trait not seen in ancestors)

• Clades are groups of organisms w/ shared traits

Phylogenic Tree (Phylogeny)

Similar to Cladogram, but includes dates