Evidence of subtle departures from Mendelian segregation in a wild lesser kestrel (Falco naumanni) population

Abstract

Some alleles are inherited more frequently than expected from Mendel's rule. This phenomenon, known as transmission ratio distortion (TRD), is found in a broad variety of taxa, but it is thought to be unusual and occurs at a low frequency in any particular population. Here, we used seven microsatellite markers to search for possible TRD in a wild lesser kestrel (Falco naumanni) population. Among the nine alleles analysed with at least 200 known meioses for each sex, we found that two of them (156-AG5 in males and 362-FN1.11 in females) presented subtle (k ¼ 0.6) but significant departures from Mendelian segregation. Moreover, in a sample of 53 alleles with at least 15 known meioses, we found a positive correlation between their transmission rates and their frequencies in the population. To estimate the transmission scores for the loci and individuals, we developed a method that allowed us to discover that another locus, FP-46, showed significant TRD, despite the lack of a significant deviation from parity for the alleles considered individually. Finally, we found a consistent transmission bias both within loci and within individuals across loci. Inter-individual differences in TRD support the idea that distorters act over several loci that are evenly distributed across the whole genome, particularly in individuals bearing the distorter alleles. Overall, these findings suggest that TRD might be a more widespread phenomenon than previously revealed by analyses at the allele level.

A RAD-based linkage map and comparative genomics in the gudgeons (genus Gnathopogon, Cyprinidae)

“…Sex-specific TRD occurs in several animals [40-42]. A study of female-specific TRD in the mouse Mus musculus suggested that the TRD was caused by the post-fertilisation reduction of female viability that involved a specific region of a chromosome [40].…”

Genetic diversity in natural and introduced island populations of koalas in Queensland

“…This is a common occurrence in inheritance studies (Reece et al 2004;Karlsson et al 2007;Li et al 2007;Guzinski et al 2008). This could be an incident of segregation distortion, a ubiquitous phenomenon, which is characterized by a deviation from expected Mendelian ratios due to high heterozygosity (Aparicio et al 2010;Liu et al 2010). It is possible that this marker is located on a portion of a chromosome affected by a segregation distorter system, a powerful evolutionary force that can affect the frequency of certain genotypes, leading to the observed transmission ratio distortion (Lyttle 1993;Aparicio et al 2010;Liu et al 2010).…”

“…This could be an incident of segregation distortion, a ubiquitous phenomenon, which is characterized by a deviation from expected Mendelian ratios due to high heterozygosity (Aparicio et al 2010;Liu et al 2010). It is possible that this marker is located on a portion of a chromosome affected by a segregation distorter system, a powerful evolutionary force that can affect the frequency of certain genotypes, leading to the observed transmission ratio distortion (Lyttle 1993;Aparicio et al 2010;Liu et al 2010). Using markers that exhibit transmission ratio distortion does pose difficulties when mapping chromosomes (Hacket & Broadfoot 2003).…”

Scrambling Eggs: Meiotic Drive and the Evolution of Female Recombination Rates

“…Currently, our knowledge of the distribution of meiotic drivers and their fitness effects is very incomplete and is likely biased toward the overrepresentation of strong drivers with extreme fitness effects. However, there is mounting evidence supporting the existence of subtle transmission ratio distorters (e.g., Zöllner et al 2004;Reed et al 2005;Aparicio et al 2010;Axelsson et al 2010) (however, the mechanism of distortion in these cases is often unknown). Similarly, although there is ample evidence that the recombination rate, as well as the strength and direction of heterochiasmy, varies across species, few allelic variants that influence sex-specific recombination rates have been identified.…”