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
 p (%) + q (%) = 1.00 (100%)

P 2 +2pq + q 2 = 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
1.
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