Multifactorial sex determination in natural populations of the housefly (Musca domestica) in Japan.

Abstract

Geographic variation in sex-determining factors was studied in 19 localities in Japan between 1981 and 1986. The association of the male-determining factor, M, was demonstrated with all linkage groups, and the most predominant carrier of the M in each locality was either the IIIM or the Y chromosome.The fraction of Y in M-carrying chromosomes was higher in Hokkaido, and declined significantly on moving to the south.The frequency of the females carrying the female-determining factor, F, which is epistatic to the M factor, was sporadically distributed in the populations surveyed. However, male heterogamety was largely retained in the populations in Hokkaido. We present a hypothesis that broadly ranging geographic variation in sex-determining factors reflects a transient state caused by recent invasions of autosomal sex-determining factors. No significant difference in the index combined with segregation rate of the Mcarrying gamete and viability was indicated between the males of X /Y and IIIMIIII.

Patterns of Neutral Genetic Variation on Recombining Sex Chromosomes

“…For example, cichlid fish in the genus Oreochromis (which includes the tilapia) have two linkage groups that contribute to sex determination, one that functions as an X/Y system and the other as Z/W (Cnaani et al 2008). Other species that have sexdetermining loci on more than one linkage group include the house fly (Tomita and Wada 1989), the platyfish (Kallman 1965), and the frog Rana rugosa (Ogata et al 2003). These systems might be at stable equilibria, or alternatively one sex determination system may be replacing another.…”

Migration and linkage disequilibrium in local populations of the housefly (Musca domestica) in Japan.

“…The method of determining the presence or the absence of the F factor in females was described in the accompanying paper (Tomita and Wada, 1989). Linkage relationships of the M factor were determined directly in the males sampled from wild populations, using the ac; ar; bwb; ye; snp mating method (Tomita and Hiroyoshi, in preparation).…”

“…Moreover, natural populations which are hard to detect the Y chromosome have been found in the United States (McDonald et al, 1975), Italy (Franco et al, 1982) and Japan (Tsukamoto et al, 1980). It is postulated that the frequency of M factor-carrying autosomes (AM) has increased in natural populations (in Japan, Hiroyoshi and Fukumori, 1977;Tomita and Wada, 1989;in Italy, Franco et al, 1982) in the past few decades.…”

“…The present study provides the experimental evidence for the above phe-nomenon, using linkage disequilibria between some isozyme marker genes and the M factor. In the populations of Hokkaido examined so far, the F factor, which makes a carrier of M develop into a fertile female, is very rare (Shono et al, 1982;Tomita and Wada, 1989).…”

“…On the other hand, the frequency of chromosome IIIM, which is the most predominant AM in Japan (Hiroyoshi and Fukumori, 1977;Tomita and Wada, 1989), is high.…”