Ch 17 Population Genetics and Speciation17. 1 Genetic VariationI. Population Genetics

A. Microevoln can be studied by observing changes in the numbers and

types of alleles in poplnsB. popln genetics – study of frequency and interaction of alleles and genes in poplns

C. Phenotypic Variation 1. organism appearance differences2. 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 ChangeI. Equilibrium and Change

A. genetic equilibrium – popln where there is no change (how realistic is this?)

B. Forces of Genetic change1. 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 412-414!)I. Forming new species

A. reproductive isolation1. two poplns can no longer interbreed2. see p 413

B. subspecies – poplns that are diverging species

C. Mechanisms of Isolation1. geography – physical barrier2. ecological niche – role species has in

env3. mating behavior and timing (frogs)4. polyploidy – plants receiving duplicate

chromosomes – so isolated5. hybridization – 2 species may mate

II. Extinction - the species that exist are net result of both speciation and extinction

Some websitesFlowers and bugshttp://www.teachersdomain.org/asset/tdc02_vid_floral/

Peacockshttp://www.pbs.org/wgbh/evolution/library/01/6/quicktime/l_016_09_56.html

Wolves – reprod isolationhttp://www.cbc.ca/clips/mov/duncombe_wolf050110.mov