Punctuated Equilibrium Verses Gradualism

What Drives Evolution

1-Isolation Temporal Geographic Behavioral

2-Artificial Selection Did not drive evolution!!!

2-Natural Selection

3-Variation & Heritability

Sources of Genetic Variation Mutations – 300 mutations in our DNA that are different from our parents mutations Only matter if they can be passed to next generation – skin cancer Sexual Reproduction – remixes the genes your parents provide into new combinations of paired alleles Lateral Gene Transfer – only in single celled creatures but significant to all evolution and current resistance to drugs. Single Gene (allele selection) Vs Polygenic Traits (phenotype selection) & how natural selection works on them. Type of Selection for Polygenic Traits: Directional / Stabilizing / Disruptive

Founder Population

Bottleneck

Genetic Drift

Evolution Vs Genetic Equilibrium Genetic Equilibrium = allele frequency in a gene pool does not change – sexual reproduction does not change change frequency. Hardy Weinberg principle = predicts allele frequency for a population and if it is wrong than it is likely that evolution is taking place. Disturbances to Equilibrium: 1.Nonrandom mating – mate selection 2.Small Population Size 3.Immigration & Emigration 4.Mutations 5.Natural Selection 6.Look at Darwin’s Finches pages

Molecular Evolution Molecular Clocks Uses rates of neutral mutations in stretches of DNA to estimate the time that two species have evolved independently of each other – page 499 Gene Duplication Gene Families such as Hox genes New copy genes evolve without changing the original Hox Genes: Mutations to this gene is significant to the body plan Dark Matter: Switches

Microevolution & Macroevolution

Mass Extinctions 5 recorded mass extinctions 1.Ordovician (440mya) - 50% of animal families 2.Devonian (360mya) - 30% of animal families 3.Permian (250mya) - 50% of animal families, including 95% of marine species 4.Triassic (210mya) - 35% of animal families 5.Cretaceous (65mya) - 60% of animal species Recovery Time 1.Ordovician - 25 million years 2.Devonian - 30 million years 3.Permian/Triassic million years 4.Cretaceous - 20 million years Many other minor extinctions Background Extinction

Mass Extinctions Current - Holocene Extinction