1.2 Evidence for Evolution
Homology
anatomical
Homologous structures: structures in different species that are similar due to common ancestry
Vestigial structures: homologous structures that are present in an organism but are no longer used
tailbone and wisdom teeth in humans
Convergent evolution: organisms independently adapt to similar environments in a similar way
not due to ancestry
Analagous structures: structures in different species that are similar due to adaptation to similar environments
developmental (embryological)
Comparative embryology: anatomical homologies not visible in adult organisms
molecular
Molecular homology: similarities in DNA sequences or amino acid sequences due to common ancestry
Fossil record
provides evidence of extinction of species, the origin of new groups, and changes within groups over time
extinctions: saber tooth cat
transitional forms: fish to land animals
ancestors of living species
Geological timescale can determine age of fossils based on:
rocks (isotopes, radioactive decay)
relative layer
chemical dating
Biogeography
How species are distributed across geography
closely related species are usually found near each other
continents and sea levels have CHANGED
Direct observation
observable, measurable changes over short periods of time
artificial selection: humans breed for specific traits