Biased Transmission Of Alleles Research Articles

Meiotic Drive and Speciation.

Meiotic drive is the biased transmission of alleles from heterozygotes, contrary to Mendel's laws, and reflects intragenomic conflict rather than organism-level Darwinian selection. Theory has been developed as to how centromeric properties can promote female meiotic drive and how conflict between the X and Y chromosomes in males can promote male meiotic drive. There are empirical data that fit both the centromere drive and sex chromosome drive models. Sex chromosome drive may have relevance to speciation through the buildup of Dobzhansky-Muller incompatibilities involving drive and suppressor systems, studied particularly in Drosophila. Centromere drive may promote fixation of chromosomal rearrangements involving the centromere, and those fixed rearrangements may contribute to reproductive isolation, studied particularly in the house mouse. Genome-wide tests suggest that meiotic drive promotes allele fixation with regularity, and those studying the genomics of speciation need to be aware of the potential impact of such fixations on reproductive isolation. New species can originate in many different ways (including multiple factors acting together), and a substantial body of work on meiotic drive point to it being one of the processes involved.

Genome-wide dissection of segregation distortion using multiple inter-subspecific crosses in rice.

Mendelian inheritance can ensure equal segregation of alleles from parents to offspring, which provides fundamental basis for genetics and molecular biology. Segregation distortion (SD) leads to preferential transmission of certain alleles from generation to generation. Such violation of Mendelian genetic principle is often accompanied by reproductive isolation and eventually speciation. Although SD is observed in a wide range of species from plants to animals, genome-wide dissection of such biased transmission of gametes is rare. Using nine inter-subspecific rice crosses, a genome-wide screen for SD loci is performed, which reveals 61 single-locus quantitative trait loci and 194 digenic interactions showing distorted transmission ratio, among which 24 new SD loci are identified. Biased transmission of alleles is observed in all nine crosses, suggesting that SD exists extensively in rice populations. 72.13% distorted regions are repeatedly detected in multiple populations, and the most prevalent SD hotspot that observed in eight populations is mapped to chromosome 3. Xian alleles are transmitted at higher frequencies than geng alleles in inter-subspecific crosses, which change the genetic composition of the rice populations. Epistatic interaction contributes significantly to the deviation of Mendelian segregation at the whole-genome level in rice, which is distinct from that in animals. These results provide an extensive archive for investigating the genetic basis of SD in rice, which have significant implications in understanding the reproductive isolation and formation of inter-subspecific barriers during the evolution.