Name that type … Macro-? Or Micro-? Type of Natural Selection? Bacteria at Harvard Type of natural selection??? CLICK

Population Genetics and Evolution 5-5

Mechanisms of evolution Evolution is change in a population over time. Gene pool - all of the alleles of a population’s genes that can be passed on

Allelic frequency B B B b b b B b b b B b b B B B B B B B What is the frequency of Allele B? There are 20 alleles total. There are 12 B. The frequency of B = 12/20 Or 0.6 What is the frequency of b? 8/20 = 0.4 Or 1- 0.6 = 0.4

Genetic equilibrium Genetic equilibrium – no change in allelic frequency of a population = no evolution (HARDY-WEINBERG principle) Changes in the gene pool / allelic frequency cause evolution

Factors that can cause evolution Mutations if they are favorable, not lethal. Genetic drift. Chance events, small populations Gene flow caused by immigration or emigration, larger populations

Speciation Members of similar populations can no longer interbreed – become different species. Caused by: A physical barrier / geographic isolation (e.g. mountain). Different environments are possible at each site and the separated populations can evolve differently. PARAPATRIC SPECIATION Reproductive isolation (e.g. mating habits, time of breeding, or physical size)

Patterns of Evolution in Populations 1. Divergent evolution Species that were once similar become more and more different. Usually because of very different environments.

2. Adaptive Radiation An ancestral species gives rise to many new species.

3. Convergent evolution Distantly related species become more similar. Occurs because of similar environments in different parts of the world Ex. Shark and dolphin

Coevolution When two different species that depend on each other evolve together (e.g. humming bird and flowers)

Australian Giant Prickly Stick Insect List 3 unique adaptive features you can infer this creature has.

Tongue of a Chameleon (click picture) Simulator CLICK

Hardy-Weinberg LAB Make 4 evenly-sized pieces of paper 2 A_s 2 a_s