Evidence for Evolution Fossils Structures Homologous Vestigial Molecular

Evidence for Evolution Fossils Structures – Homologous, Vestigial Molecular Biology

Fossils • Can trace evolutionary history – see earlier forms of an organism

Fossils • Can locate when organisms lived (approx)

Homology or Analogy? Front leg of dog Front flipper of whale

Similar structures indicate common ancestry, even though functions are different

Analogous structures have similar functions, but different structures – thus not closely related

Vestigial Structures

Lamark • 1744 -1829 • An organism can acquire and then pass on characteristics during its lifetime to its offspring. • Giraffe example – stretched their necks to reach food and were able to pass that on to offspring • Frog “grew webbed feet to swim better” and passed that on to offspring

Darwin • 1809 -1882 • Medical School, seminary, naturalist • 1831 Beagle Voyage – 5 years – Galapagos Isl.

Darwin • Darwin’s voyage solidified his ideas on how living things change over time • All species of life have descended from a common ancestor • 1859 – On the Origin of Species

Galapagos Discoveries • Beak adaptions

For Evolution to Happen: Overproduction – more individuals are produced than can survive – shad eggs that we saw Struggle – organisms compete for resources – water, food, light Variation – with a population, no two individuals are identical - vary in size, speed, color disease resistance Selection – some are better suited for their environment – “Selected For” and reproduce

Theory of Natural Selection • Those individuals which are best adapted to their environment, are more likely to survive long enough to reproduce – thus passing on the genes for those traits to their offspring

Assume 2 things • There a variety of traits to begin with – if not, a species won’t evolve, and might go extinct • There are environmental pressure giving some of those traits an advantage, other a disadvantage – if not, a population stays the same( there’s no pressure to evolve)

Example of Natural selection • Peppered Moths • http: //www. robinhamer. com/next/thinking/ moth/index. html