Effect of a founder event on variation in the genetic sex-determining system of the fire ant Solenopsis invicta.
Effect of a founder event on variation in the genetic sex-determining system of the fire ant Solenopsis invicta.
复制标题
创始人事件对火蚁红火蚁遗传性别决定系统变异的影响。
作者：
K. Ross;Edward L. Vargo;Laurent Keller;James C. Trager
研究了最近的一次创始人事件对火蚁Solenopsis invicta野生种群遗传多样性的影响，特别是遗传性别决定系统。在火蚁引进种群中，二倍体雄性比单倍体雄性要常见得多，而产生二倍体雄性的蜂王在交配后中所占的比例也明显高于本地种群。本地种群和引进种群在交配系统属性(即王后交配频率或近亲交配水平)上的差异可以排除为导致这些二倍体雄性生产水平不同的因素。因此，我们得出结论，二倍体雄性在引入种群中的频率增加，这是由于性别决定基因(Locus)上等位基因多样性的丧失。这种性等位基因的丧失导致了与引进种群中不育二倍体雄性的产生相关的估计分离遗传负荷大大增加，超过了本地种群的负荷。在引入的不列颠链霉菌中，性别决定系统中的等位基因多样性的丧失与蛋白质编码基因座上可电泳性检测的稀有等位基因的丧失是平行的。这些不同类型的标记之间的这种一致性是可以预测的，因为在当地人口中存在的许多性别等位基因中的每一种都预计是罕见的。基于76个电泳酶基因座的预期杂合度(Hexp)估计在本地和引进的火蚁种群之间没有显著差异，说明这种方法在检测许多类型的瓶颈方面缺乏敏感性。
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.