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Inbreeding results in homozygosity which can increase the chances of offspring being affected by recessive traits. [3] In extreme cases, this usually leads to at least temporarily decreased biological fitness of a population [ 4 ] [ 5 ] (called inbreeding depression ), which is its ability to survive and reproduce.
The hypothesis states that inbreeding increases the amount of overall homozygosity—not just locally in the MHC, so an increase in genetic homozygosity may be accompanied not only by the expression of recessive diseases and mutations, but by the loss of any potential heterozygote advantage as well. [17] [2] Animals only rarely avoid inbreeding ...
The words homozygous, heterozygous, and hemizygous are used to describe the genotype of a diploid organism at a single locus on the DNA. Homozygous describes a genotype consisting of two identical alleles at a given locus, heterozygous describes a genotype consisting of two different alleles at a locus, hemizygous describes a genotype consisting of only a single copy of a particular gene in an ...
Genetic purging is the increased pressure of natural selection against deleterious alleles prompted by inbreeding. [1]Purging occurs because deleterious alleles tend to be recessive, which means that they only express all their harmful effects when they are present in the two copies of the individual (i.e., in homozygosis).
Therefore, a balance exists between inbreeding and inbreeding avoidance. This balance determines whether inbreeding mechanisms develop and the specific nature of such mechanisms. [3] A 2007 study showed that inbred mice had significantly reduced survival when they were reintroduced into a natural habitat. [4]
An example of inbreeding depression is shown in the image. In this case, a is the recessive allele which has negative effects. In order for the a phenotype to become active, the gene must end up as homozygous aa because in the geneotype A a , the A takes dominance over the a and the a does not have any effect.
For example, the step-wise reintroduction strategy of the Alpine Ibex in the Swiss Alps created several strong population bottlenecks that reduced the genetic diversity of the newly introduced individuals. The effect of inbreeding in the resulting sub-populations could be studied by measuring the runs of homozygosity in different individuals.
One of the more specific uses of Drosophila inbred strains is the use of Gal4/UAS lines in research. [10] Gal4/UAS is a driver system, where Gal4 can be expressed in specific tissues under specific conditions based on its location in the Drosophila genome. Gal4 when expressed will increase the expression of genes with a UAS sequence specific to ...