Blog Post Module 8: Reflection
There are several factors that keep genetic variation from eroding over time; some of which include non random mating, genetic drift, and gene flow.
Genetic drift: is a force of evolution that can cause random changes to a populations allele frequencies.
Gene flow/Migration can affect a population in a few ways
1) Migration can homogenize allele frequencies of multiple connected populations.
2) Migration can create genetic diversity by introducing new alleles from one population to another population.
Migration acts as a homogenizer but also introduces new genetic material to populations.
Crossing over and recombination: These events can increase genetic variation by allowing new allele combinations; from generation to generation, offspring have a greater chance of being genetically different from their parents.
Mutation causes a change in DNA sequencing, and in addition, creates new alleles to be passed on in a population
Depending on what kind of organism is being observed and what kind of non-random mating is exhibited, this force can create new genetic variation within a population. One type of non-random mating, inbreeding, decreases genetic variation. Another category of non-random mating, outbreeding, increases genetic variation. These opposite modes of non-random mating can be controlled by humans or occur randomly in nature.
This is an interesting article concerning populations recovering from bottleneck effects:
They study involved researchers trying to find real life evidence of a rescue effect in a population of these ground squirrels. The researchers studied a population of the squirrels that had bottle neck effect that lasted about four years. The results of the genetic analyzation showed that while less than ten squirrels in the population remained, the effect of immigration kept the allele frequency from reaching a point of 100% heterozygosity (which usually happens in bottle necks. Also, the results of the study showed that there wasn't really a loss of fitness in the population.
Genes seem to mix and change continuously in a way that they keep somewhat of an equilibrium.
This study implies that outbreeding/gene flow can increase genetic diversity. Out breeding is also something zoos do with their breeding animals, in order to keep the genetic material of the animals in captivity diverse.
sources
No comments:
Post a Comment