Population genetics
This presentation is the property of its rightful owner.
Sponsored Links
1 / 14

Population Genetics PowerPoint PPT Presentation


  • 72 Views
  • Uploaded on
  • Presentation posted in: General

Population Genetics. Terminology. Population - a localized group of individuals capable of interbreeding and producing fertile offspring Gene Pool - all of the alleles for all genes in all individuals of the population. Major factors that alter allele frequency. Genetic Drift Gene Flow

Download Presentation

Population Genetics

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Population genetics

Population Genetics


Terminology

Terminology

Population - a localized group of individuals capable of interbreeding and producing fertile offspring

Gene Pool - all of the alleles for all genes in all individuals of the population


Major factors that alter allele frequency

Major factors that alter allele frequency

Genetic Drift

Gene Flow

Natural Selection


Genetic drift

Genetic Drift

These are chance events that cause allele frequencies to fluctuate unpredictably from one generation to the next

Tends to reduce genetic variation through losses of alleles

Two main types:

Founder effect

Bottle neck effect


In addition to natural selection genetic drift gene flow cause change

In addition to natural selection, genetic drift & gene flow cause change

  • Random change in the gene pool that occurs in a small colony of a population

  • 1814 – 15 people founded a British Colony on Tristan da Cunha. One person carried a recessive allele for retinitis pigmentosa (progressive form of blindness). In the 1960’s the island descendants were samples – of 240 individuals, 4 had the disease. The frequency for the disease is much higher among islanders than the area from which the founders came.

Founder Effect

Example


Bottleneck effect

Bottleneck Effect

A sudden change in the environment (flood / fire) that drastically reduces the population size; In the surviving population certain alleles may be over or under represented


Bottleneck example

Bottleneck example

Northern Elephant Seals were heavily hunted by man in the early 19th century reducing their population size to about 20 individuals.  Today the population has rebounded to over 30,000 but the effects of the bottleneck are evident in their DNA.  There is little genetic variation among this population when compared to a population of Southern Elephant seals that were not heavily hunted.


Gene flow

Gene Flow

The transfer of alleles into or out of a population due to movement of fertile individuals or their gametes

For example - movement of pollen by wind or insects; movement of humans around the globe


Bottleneck gene flow or founder effect

Bottleneck, Gene Flow or Founder Effect?

  • Flower population: ww = white flower; WW and Ww = purple flower; a mud slide wipes out most of the white flowered plants. What type of event occurred?


Bottleneck gene flow or founder effect1

Bottleneck, Gene Flow or Founder Effect?

  • Genetic modifications from transgenic plants passed to neighboring populations of wild relatives. What type of event occurred?


Bottleneck gene flow or founder effect2

Bottleneck, Gene Flow or Founder Effect?

  • Millions of greater prairie chickens once lived on the prairies of Illinois. As these prairies were converted to farmland and other uses during the 19th and 20th century, the number of greater prairie chickens plummeted to less than 50 individuals. The few survivors have low levels of genetic variation. What type of event occurred?


Bottleneck gene flow or founder effect3

Bottleneck, Gene Flow, or Founder Effect?

  • This event resulted in the world wide spread of several insecitcide-resistance alleles in the mosquito Cluexpipiens, a vector for West Nile virus and Malaria. What type of event occurred?


Bottleneck gene flow or founder effect4

Bottleneck, Gene Flow or Founder Effect?

  • Which type of event explains the high incidence of polydactylism found in the Amish population?


Bottleneck gene flow or founder effect5

Bottleneck, Gene Flow, or Founder Effect?

  • Reduction in geographic variation in the appearance of humans is caused by what type of event?


  • Login