Hardy- Weinberg Equilibrium What Happens if it doesn’t

Hardy -Weinberg Under certain conditions the frequency of an allele will remain the same

Hardy -Weinberg No Mutation No immigration or emigration Large population No Natural Selection Random Mating

Hardy -Weinberg Use p & q to represent allele frequency P2 +2pq + q2 = 1.00 (100%)

Disruptions to Equilibrium Mutations Could produce new alleles (spontaneous) Hard to eliminate harmful recessives If helpful become part of population

Disruptions to Equilibrium Migration Emigration – exit Immigration – into

Disruptions to Equilibrium Genetic drift Allele frequencies change Happens in small population Leads to no variation & possible extinction

Disruptions to Equilibrium Non random mating Geographic proximity Many species have mate selection

Disruptions to Equilibrium Natural selection stabilizing – selects for the average directional – selects for extreme disruptive–selects for either end sexual – choose mates  

Concepts of species morphological based on looks - what look like 2 different species can breed & produce fertile off spring

Concepts of species biological – populations of organisms that can breed & produce fertile offspring, but do not breed with other groups

Concepts of species Modern – single type of organism that are morphologically similar, can interbreed & produce fertile offspring

Types of speciation Allopatric speciation Results because a physical barrier is present

Types of speciation Sympatric Speciation Results when there are no barriers, from natural selection, mutation and genetic drift

Isolation Mechanism geographic – physical separation (island & rivers) 2. Reproductive – unsuccessful breeding

Reproductive isolation Post- zygotic – after fertilize offspring can’t reproduce Ex: mule, seedless grape  

Reproductive isolation Pre – zygotic before fertilize Ex: mating times

Rates of Speciation gradual – slow shift in the forms that are seen punctuated – sudden shift in the forms seen in the fossil record