The genetics of Drosophila subobscura populations XIII. A study of lethal allelism

Abstract

The rate of allelism of lethals on the O chromosome of Drosophila subobscura in two natural populations and the interpopulation allelism rate are 0.0062, 0.0025 and 0.0058 respectively. They do not differ statistically. It is concluded that the natural populations studied have practically an infinite size. This conclusion is corroborated by ecological data on density and dispersion, and partly by data based on the temporal method. The allelism rate of genes producing male and female sterility was also studied. From the study of the allelism rate for lethal and sterility genes the number of such genes on the O chromosome ofD. subobscura was inferred.

Evolution of Chilean colonizing populations of Drosophila subobscura: lethal genes and chromosomal arrangements

“…Thus, lethal genes along the O chromosome are not distributed at random. As mentioned previously, the percentages of allelism have been corrected using the method proposed by Loukas et al 1980, which transforms the SI ? SII lethal chromosomes into SII lethal ''equivalents.''…”

“…The O 7 alone is thought to be the result of a very rare recombination event between an O 3?4?7 chromosome and an O st one. Most probably, the linkage disequilibrium for the inversions O 3?4 and O 7 is due to an extreme reduction of crossing over in the region between them (Sperlich and Feuerbach-Mravlag 1974 (Mestres et al 1990(Mestres et al , 1992(Mestres et al , 1995Solé et al 2000) presented only two kinds of allelic (Loukas et al 1980) and in chromosome II of D. melanogaster (p ? = 0.0029) (Begon et al 1985).…”

“…This may be due to the fact that in small (i.e., marginal) populations lethal genes are purged at a faster rate because of inbreeding. However, frequencies of lethal genes on the O chromosome of D. subobscura in its native range are higher than expected in several marginal populations, and these frequencies display a wide range of variation (Sperlich et al 1977;Loukas et al 1980;Pfriem and Sperlich 1982;Mestres et al 1990;Saura et al 1990Saura et al , 1998Zivanovic et al 2000). In contrast, observed frequencies of lethal genes are low in colonizing populations of D. subobscura in America, reflecting the founder event (Mestres et al 1990(Mestres et al , 1992(Mestres et al , 1995Solé et al 2000).…”

“…A few studies have analyzed lethal allelism in Paleactic populations of D. subobscura. Loukas et al (1980) found low frequencies of this allelism in Electronic supplementary material The online version of this article (doi:10.1007/s10709-008-9298-y) contains supplementary material, which is available to authorized users. populations on Mt.…”

O-chromosome lethal frequencies in Serbian and Montenegrin Drosophila subobscura populations

“…Depending on the timing of sample collec tion the genetic structure of the population could dif fer and this could be reflected in the lethal frequencies. When populations were sampled during the first pop ulation expansion period (spring), the effective popu lation size, measured by lethal allelism, was enormous and the lethal frequency was high [28][29][30]. When the population was sampled in the second expansion peri od (autumn), the effective population size was large, but not enormous, and the lethal frequencies were not as high [29].…”