Extra Credit Kevin Schlang BIO311D

Population Genetics

Genetic Variations in Populations

Allele Frequency= Gene Frequency= gametic frequency

Def: The proportion of a certain allele within a population

Gene Pool: The set of all alleles at all Loci of a population

MN blood type example

Frequencies of Alleles for blood types similar in populations closer to each other

New Guinea and Australia are similar, but Guatamala almost opposite

Example used to explain % Frequence

N/total X 100

The Hardy-Weinberg genetic equilibrium

The allele and genotypic frequencies remain the same from generation to generation in a population in which there is

Factors in order for Hardy-Weinberg equilibrium to exist

Infinite large population size

Random mating

No Selection

No mutations

No migration

Equation

p^2+2pq+q^2=1

P^2=Frequency of Homozygous Dominant Species

q^2= frequency of homozygous recessive allele

2pq=frequency of heterozygous genetype

Def: Random changes in the genetic code

Facts

mutation rates for many genes vary between one out of ten to one hundred thousand

mutation is the ultimate source of genetic variation in populations.

the majority of mutations are detrimental in a given environment

Def: random changes in allele frequencies in a population from generation to generation.

genetic drift results from sampling error in a population with limitied size.

Effects from Genetic Drift

Founder Effect

random changes in allele frequencies in a population during colonization.

founder effect occurs within the same generation.

Bottleneck effect

random changes in allele frequencies in a population due to dramatic reduction of population size.

Reduction in size is caused either by some catastrophic events (density- independent factors) or only the frequencies of those loci are conside

Speciation

2 Types

Allopatric

Def: species formation from a common ancestor in geograpghically separate locations

2 Models of Allopatric Speciation

Dumb-Bell Model

Ancestrol species divides into two almost equal halves each of which forms a new species.

Peripheral Isolate Model

New Species forms from population isolated at edge of ancestrol species range

Sympatric

Def: differentiating and acquiring reproductive isolation within the same area (sym=together, patria=homeland)

Polyploidy

Examples

Apple maggot fly

polinating species becoming more keen to one type of plant.

Adaptive Radiation

When one or very few species give rise to many new species within a relatively short period of time.

Example

Darwins Finches

Finches in diferent areas beaks developed changes creating several species.

Pollution in Ecosystems

Pollution due to pestecyes

Aerosol Used to spray insects which remains in Atmoshere for a long time

DDT Example

Sprayed during WW2 to get insects away. However in 60's if was found that it results in thinner eggshells which relates to decline in number of bird species during the time.

Biomagnification increases concentration of DDT, and DDT remained in soil for long time.

Figuring how pollution has changed

Ice Croe from greenland

Pull out core of ice and snow and it will show anual rings with airpockets. Air in pockets can be analyzed and one can look at nitrogen content.

Coolants

Coolants Contribute to ozone thinning.

Acid Rain

Sulfuric and Nitric Acids contribute to increase PH in rain in areas from pollution from fossil fuels.

Global Warming

Ozone Depletion causing temp increase more in northpole and contributing to increase in skin cancer in more south pole areas.

Def: Increase in global temp.

Physical Enviornmental Impacts

Melting of arctic ice and glaciers

rising sea levels

Changes in Percipitation

Projected increase of 4 degrees Celcius in next 4 years

Biological Impacts

Earlier spring events

Polward shifts of species ranges

Ex Beech trees ranges have already moved north

Largescale destruction of tropical rainforests

Species Extinction

76 species of frogs

Polar bears