Meiotic drive (or segregation distortion) is a phenomenon that occurs when one a
ID: 200406 • Letter: M
Question
Meiotic drive (or segregation distortion) is a phenomenon that occurs when one allele manipulates the process of meiosis, so that heterozygotes produce gametes with this allele more than 50% of the time. For example, imagine that the A1 allele is a segregation distorter that—in A1/A2 heterozygotes—causes five-sixths of gametes to carry A1 and only one- sixth of gametes to carry A2. Gamete production in homozygotes is not affected. How should we change our “cards in a bag” simulation to include the effects of this meiotic drive?
Explanation / Answer
Meiotic drive:-
It is a type of selfish genetic element which manipulate meiosis so that the chromosome where they reside is transmitted to more than 50% of the offspring of a heterozygous carrier.
Segregation distorters gain their transmission advantage by multiple mechanisms, such as incapacitating gametes that carry the alternative allele
or
influencing the geometry of chromosome segregation during the first meiotic division.
Segregation distorters give rise to genetic conflicts among loci, as natural selection favors alleles at unlinked loci that suppress distortion and alleles in close linkage that enhance distortion.
Sex chromosomes and segregation distortion:--
Segregation distorters can arise on all chromosomes, but are particularly important in species with chromosomal sex determination.
Theory suggests that segregation distorters are more likely to arise on sex chromosomes than on autosomes.
To gain a transmission advantage, segregation distorters must meet two conditions.
First, the distorter must be able to discriminate its host chromosome from its homolog.
Second, the distorter and responder loci must be in strong linkage, as otherwise recombination will generate suicide chromosomes which carry the distorter and a sensitive responder.