Ch 17 Population Genetics and Speciation Genetic Variation I.Population Genetics A. Microevoln can be studied by observing changes in the numbers and types of alleles in poplns B. popln genetics – study of frequency and interaction of alleles and genes in poplns

C. Phenotypic Variation 1. organism appearance differences 2. normal distribution – bell curve – cluster of data around an average value D. The major source of new alleles in natural poplns is mutation in germ cells.

17.2 Genetic Change I.Equilibrium and Change A. genetic equilibrium – popln where there is no change (how realistic is this?) B. Forces of Genetic change 1. gene flow – genes are added or removed to popln – imigration or emigration 2. nonrandom mating (alpha male?) 3. genetic drift – random changes in alleles

4. mutation 5. natural selection – eliminates ind from a popln – so those traits won’t be passed on II. Popln size and evoln  allele frequencies are more stable in large poplns III. Patterns of Natural Selection (p 409)

17.3 Speciation (Read p !) I.Forming new species A. reproductive isolationreproductiv 1. two poplns can no longer interbreed 2. see p 413 B. subspecies – poplns that are diverging species

C. Mechanisms of Isolation 1. geography – physical barrier 2. ecological niche – role species has in env 3. mating behavior and timing (frogs) 4. polyploidy – plants receiving duplicate chromosomes – so isolated 5. hybridization – 2 species may mate II. Extinction - the species that exist are net result of both speciation and extinction

Some websites Flowers and bugs Peacocks Wolves – reprod isolation