James A C, Jaenike J
Department of Biology, University of Rochester, New York 14627.
Genetics. 1990 Nov;126(3):651-6. doi: 10.1093/genetics/126.3.651.
We document the occurrence of "sex ratio" meiotic drive in natural populations of Drosophila testacea. "Sex ratio" males sire greater than 95% female offspring. Genetic analysis reveals that this effect is due to a meiotically driven X chromosome, as in other species of Drosophila in which "sex ratio" has been found. In contrast to other drosophilids, the "sex ratio" and standard chromosomes of D. testacea do not differ in gene arrangement, implying that the effect may be due to a single genetic factor in this species. In all likelihood, the "sex ratio" condition has evolved independently in D. testacea and in the Drosophila obscura species group, as the loci responsible for the effect occur on different chromosomal elements. An important ecological consequence of "sex ratio" is that natural populations of D. testacea exhibit a strong female bias. Because D. testacea mates, oviposits, and feeds as adults and larvae on mushrooms, this species provides an excellent opportunity to study the selective factors in nature that prevent "sex ratio" chromosomes from increasing to fixation and causing the extinction of the species.
我们记录了在果蝇（Drosophila testacea）自然种群中“性比”减数分裂驱动的发生情况。“性比”雄性果蝇产生的雌性后代超过95%。遗传分析表明，这种效应是由一条减数分裂驱动的X染色体导致的，就像在其他已发现“性比”现象的果蝇物种中一样。与其他果蝇科物种不同的是，果蝇（D. testacea）的“性比”染色体和标准染色体在基因排列上没有差异，这意味着该效应可能是由该物种中的单一遗传因素引起的。很有可能，“性比”情况在果蝇（D. testacea）和果蝇（Drosophila obscura）物种组中是独立进化的，因为导致这种效应的基因座位于不同的染色体元件上。“性比”的一个重要生态后果是，果蝇（D. testacea）的自然种群表现出强烈的雌性偏向。由于果蝇（D. testacea）的成虫和幼虫都在蘑菇上交配、产卵和取食，该物种为研究自然界中阻止“性比”染色体增加到固定状态并导致物种灭绝的选择因素提供了绝佳机会。
