Unit One Evolution and Genetics Chapters 20, 21, and 22

Genes Within Populations Chapter 20

Darwin British Naturalist Theory of Natural Selection

Nuts and Bolts of the Theory Species accumulate differences over time Individuals pass on their traits Descendants differ from ancestors New species can therefore arise from old species

Major Agent of Change Not all organisms are the same Some organism’s differences are better adaptations Better adaptations are passed on Populations gradually change Populations are better adapted to LOCAL circumstances

Measuring allele frequencies Approach #1 o Electrophoresis to separate proteins RFLP’s or SNP’s Approach #2 o Hardy-Weinberg prediction Mutations Population genetics

Hardy-Weinberg Assumptions o No mutation takes place o No immigration or emigration o Mating is random o Population size is large o No selection occurs o Mr. Anderson Hardy-Weinberg Mr. Anderson Hardy-Weinberg

Five Agents of Change Mutation changes alleles Gene flow—when alleles move between populations Nonrandom mating shifts genotype frequencies Genetic drift may alter allele frequencies in small populations Selection favors some genotypes over others

Did you notice anything about the agents of change and Hardy-Weinberg? Explain what you noticed.

Nonrandom mating Assortative MatingDisassortative Mating Phenotypically similar organisms mate Essentially inbreeding Phenotypically different organisms mate Hybrids produced

Genetic Drift: Bottleneck Effect What types of scenarios could possibly cause this?

Genetic Drift: Founder Effect What happened? Explain a mechanism whereby this could occur.

Bottleneck and Founders Effect Examples Northern Elephant Seal Amish communities

Selection Phenotypic variation between individuals exist Variation between individuals results in differences of surviving offspring in the next generation Phenotypic variation has a genetic basis Rock Pocket Mouse

Darwin’s Fitness According to Darwin what is fitness?

Natural Selection Revisited Negative frequency dependent selection Positive frequency dependent selection Oscillating selection o Changes occur based on environmental pressures o Example in next chapter: finch beak shape due to precipitation Heterozygote advantage o Sickle cell anemia

Other Selection Types Disruptive Directional Stabilizing

The Evidence for Evolution Chapter 21

Artificial Selection Certain phenotypes are favored

Russian Foxes

Homologous Structures

Vestigial Structures

Convergence and Biogeography

The Origin of Species Chapter 22

Sympatric Species Phenotypically different Utilize different habitats Behave differently

Subspecies

Biological Species Concept Sympatric species if they were to mate would become homogenized Ernst Mayr and the concept o Defines species as “…groups of actually or potentially interbreeding natural breeding populations which are reproductively isolated from other such groups.” o In other words, you must be able to reproduce and produce fertile offspring to be a species How could a species be reproductively isolated?

Geographic Isolation

Adaptive Radiation Notable examples include island habitats Hawaii Galapagos

Character displacement A system where individuals that do not use the same resources are favored by natural selection

Micro and Macroevolution Stickleback Evolution