Recent evolution of mousethaplotypes at polymorphic microsatellites associated with thetcomplex responder (Tcr) locus

Abstract

Microsatellites closely associated with each member of the TcplO gene family were amplified simultaneously from t haplotype and wild-type forms of mouse chromosome 17, by PCR. The t complex responder {Tcr) locus, which plays a central role in transmission ratio distortion, maps within the TcplO cluster on the t haplotype. Thus the amplified set of microsatellite loci (referred to collectively as TcplOms) provides a direct marker for this central component of the meiotic drive system associated with all naturally occurring t haplotypes. A unique TcplOms pattern of microsatellite alleles was obtained for a number of independent, laboratory-maintained complete and partial t haplotypes. Independent t chromosomes found in wild mice from US populations also had unique patterns, even when they were classified within the same lethal complementation group. Wild and laboratory chromosomes in the t w5 group showed similarly-sized but non-identical TcplOms patterns, suggesting they share a recent common ancestor. These chromosomes are likely to have derived from an ancestral chromosome within the founding population of North American house mice. The TcplOms pattern was also shown to be useful in field studies for distinguishing among independent t haplotypes, when more than one is present within a single population.

Mate choice for genetic compatibility in the house mouse

“…Drive of the t haplotype amplifies the cost of genetic incompatibility by increasing the frequency at which t / t are produced when both males and females are carriers. In laboratory crosses between +/ t and +/+, we found that the t haplotype when transmitted solely paternally is inherited by nearly all offspring (a proportion of 0.90), which is consistent with the range of 0.88–0.99 reported in crosses of wild mice (Dunn ; Ardlie and Silver ; Carroll et al. ).…”

EVOLUTION AT THE MOUSE t COMPLEX: WHY IS THE t HAPLOTYPE PRESERVED AS AN INTEGRAL UNIT?

“…In the same manner, the relative fertility of a fully heterozygous D 1 D 4 RD 3 D 2 /ϩϩϩϩϩ male would be 0.66 or 0.81, instead of 1.0. These numbers are not incompatible with the studies of Johnston and Brown (1969) and Ardlie and Silver (1996a).…”

“…Moreover, transmission ratios may vary depending on the timing of mating. In particular, the segregation ratios in litters conceived from postpartum estrus may be lower than those in litters conceived from cycling estrus (Lenington and Heisler 1991; but see Ardlie and Silver 1996a). Other factors that are likely to reduce the frequency of the complete t haplotype are female preferences for non-t males as mates (e.g., Lenington and Heisler 1991), inbreeding (e.g., Petras 1967), and strong seasonal or spatial fluctuations in population size.…”

“…For a variety of reasons, the distorter alleles have additional negative fitness effects in heterozygous condition (e.g., Johnston and Brown 1969;Ardlie and Silver 1996a;Ardlie 1998 and references therein). This is especially so for heterozygous males.…”

Transmission ratio distortion in the human body louse, Pediculus humanus (Insecta: Phthiraptera)

“…Inheritance in P. humanus males is therefore similar to TRD such as segregation distorter in D. melanogaster (Lyttle, 1993), and the t-locus in Mus domesticus and M. musculus (Ardlie and Silver, 1996) in that one allele is transmitted predominantly (95-99%) to offspring in some males. In this study, the only P. humanus heterozygous male in which alleles segregated in a Mendelian fashion (F 1 male of family 9) was from a family in which TRD of paternal alleles occurred (family 7).…”