Ross K G, Vargo E L, Keller L, Trager J C
Department of Entomology, University of Georgia, Athens 30602-2603.
Genetics. 1993 Nov;135(3):843-54. doi: 10.1093/genetics/135.3.843.
Effects of a recent founder event on genetic diversity in wild populations of the fire ant Solenopsis invicta were studied, with particular attention given to the genetic sex-determining system. Diploid males are far more common relative to haploid males in introduced populations than in native populations of fire ants, and queens that produce diploid males account for a significantly larger proportion of the mated queens in introduced than in native populations. Differences between native and introduced populations in attributes of the mating systems (i.e., queen mating frequency or level of inbreeding) can be excluded as factors contributing to these different levels of diploid male production. Thus, we conclude that diploid males have increased in frequency in introduced populations because of a loss of allelic diversity at the sex-determining locus (loci). This loss of sex alleles has generated a substantial increase in the estimated segregational genetic load associated with production of sterile diploid males in introduced populations over the load in native populations. The loss of allelic diversity in the sex-determining system in introduced S. invicta is paralleled by a loss of electrophoretically detectable rare alleles at protein-encoding loci. Such concordance between these different types of markers is predicted because each of the many sex alleles present in the native populations is expected to be rare. Estimates of expected heterozygosity (Hexp) based on 76 electrophoretic loci do not differ significantly between the native and introduced fire ant populations, illustrating the lack of sensitivity of this measure for detecting many types of bottlenecks.
研究了近期一次奠基者事件对红火蚁入侵红火蚁野生种群遗传多样性的影响，特别关注了遗传性别决定系统。与红火蚁原生种群相比，在引入种群中，二倍体雄蚁相对于单倍体雄蚁更为常见，并且产生二倍体雄蚁的蚁后在引入种群中占已交配蚁后的比例显著高于原生种群。交配系统属性（即蚁后交配频率或近亲繁殖水平）在原生种群和引入种群之间的差异可以排除为导致二倍体雄蚁产生水平不同的因素。因此，我们得出结论，引入种群中二倍体雄蚁的频率增加是由于性别决定位点上等位基因多样性的丧失。与原生种群相比，这种性等位基因的丧失导致引入种群中与不育二倍体雄蚁产生相关的估计分离遗传负荷大幅增加。引入的入侵红火蚁性别决定系统中等位基因多样性的丧失与蛋白质编码位点上电泳可检测到的稀有等位基因的丧失同时发生。预计这些不同类型的标记之间会出现这种一致性，因为原生种群中存在的许多性等位基因中的每一个都预计是稀有的。基于76个电泳位点的预期杂合度（Hexp）估计值在原生红火蚁种群和引入红火蚁种群之间没有显著差异，这表明该指标在检测多种类型瓶颈方面缺乏敏感性。
