University of Stirling, Stirling FK9 4LA, Scotland.
Mol Ecol. 2012 Aug;21(16):3988-95. doi: 10.1111/j.1365-294X.2012.05679.x. Epub 2012 Jun 27.
Hymenopteran species with single-locus complimentary sex-determination (sl-CSD) face an additional cost of inbreeding because of a loss of diversity at the sex-determining locus. Laboratory studies of a range of Hymenoptera have found that a small percentage of diploid males produce viable diploid sperm, and that if these males mate, then the resultant females produce triploid offspring that are sterile. Here, we use microsatellite markers to determine the frequency of triploid individuals of Bombus muscorum and B. jonellus in a model island system. Triploids were found in populations of both species. Observed triploid frequencies of up to 8% were detected, and estimated total frequencies peaked at 20% with respect to normal diploid workers. For both species, triploid frequency was negatively correlated with surrogates of population size, providing direct evidence for inbreeding in small populations. Populations limited to <∼15 km(2) of suitable habitat were particularly likely to harbour triploids. Estimated total triploid frequencies were higher in B. muscorum than in B. jonellus, perhaps due to the greater dispersal range of the latter species. Implications for the conservation of rare social hymenopterans are discussed.
具单基因座互补性别决定（sl-CSD）的膜翅目物种由于性决定基因座多样性的丧失而面临额外的近亲繁殖成本。对一系列膜翅目昆虫的实验室研究发现，一小部分二倍体雄性会产生有活力的二倍体精子，如果这些雄性交配，那么产生的雌性后代将是不育的三倍体。在这里，我们使用微卫星标记来确定在模型岛屿系统中熊蜂属和姬蜂属的三倍体个体的频率。在这两个物种的种群中都发现了三倍体。检测到高达 8%的观察三倍体频率，估计总频率在正常二倍体工蜂中达到 20%的峰值。对于这两个物种，三倍体频率与种群大小的替代指标呈负相关，这为小种群中的近亲繁殖提供了直接证据。受限于 <∼15 平方公里适宜栖息地的种群特别可能存在三倍体。估计总三倍体频率在熊蜂属中高于姬蜂属，这可能是由于后者的扩散范围更大。讨论了对稀有社会性膜翅目昆虫保护的影响。
