Evolution & Natural Selection Chapter 11

What is evolution? What is biological evolution?

What does that mean? Genetic makeup = Genetic change =

What causes changes in allele frequencies in a population What causes changes in allele frequencies in a population? (Mechanisms of evolution) Mutation Natural selection Artificial selection Sexual selection

Mutation

Natural selection Three conditions are necessary for this to occur

1. Variation for a trait

Variation for a behavioral trait

2. Heritability

3. Unequal reproductive success

Measuring reproductive success Fitness is a measure of

Natural selection, cont.

Natural selection, cont. Leads to evolutionary adaptation

Natural selection is NOT. . . . . . a choice. Organisms do not evolve because they want to or “need” to.

Remember what we’re talking about? Mechanisms of evolution: Mutation Natural selection Artificial selection Sexual selection

Artificial selection

Sexual selection Same conditions apply. . . results:

Sexual selection continued Leads to sexual dimorphism

Remember what a theory is?

Evidence of evolution Geology Fossil record Biogeography Comparative anatomy & embryology Molecular biology Laboratory & field experiments

Comparative anatomy Anatomical similarities between species give signs of common ancestry Homologous structures: Vestigial organs:

Molecular biology