Liebert Aviva E, Sumana Annagiri, Starks Philip T
Biology Department, Dana Laboratories, Tufts University, Medford, MA 02155, USA.
Biol Lett. 2005 Jun 22;1(2):200-3. doi: 10.1098/rsbl.2004.0284.
Although the hymenopteran sex-determining mechanism generally results in haploid males and diploid females, diploid males can be produced via homozygosity at the sex-determining locus. Diploid males have low fitness because they are effectively sterile or produce presumably sterile triploid offspring. Previously, triploid females were observed in three species of North American Polistes paper wasps, and this was interpreted as indirect evidence of diploid males. Here we report what is, to our knowledge, the first direct evidence: four of five early male-producing Polistes dominulus nests from three populations contained diploid males. Because haploid males were also found, however, the adaptive value of early males cannot be ignored. Using genetic and morphological data from triploid females, we also present evidence that both diploid males and triploid females remain undetected throughout the colony cycle. Consequently, diploid male production may result in a delayed fitness cost for two generations. This phenomenon is particularly relevant for introduced populations with few alleles at the sex-determining locus, but cannot be ignored in native populations without supporting genetic data. Future research using paper wasp populations to test theories of social evolution should explicitly consider the potential impacts of diploid males.
虽然膜翅目昆虫的性别决定机制通常会产生单倍体雄性和二倍体雌性，但通过性别决定位点的纯合性可以产生二倍体雄性。二倍体雄性的适合度较低，因为它们实际上是不育的，或者会产生可能不育的三倍体后代。此前，在北美三种墨胸胡蜂属纸黄蜂中观察到了三倍体雌性，这被解释为二倍体雄性存在的间接证据。在此，据我们所知，我们报告了首个直接证据：来自三个种群的五个早期产雄的意大利蜜蜂巢中有四个包含二倍体雄性。然而，由于也发现了单倍体雄性，早期雄性的适应性价值不能被忽视。利用三倍体雌性的遗传和形态学数据，我们还提供了证据表明二倍体雄性和三倍体雌性在整个蜂群周期中都未被发现。因此，二倍体雄性的产生可能会导致两代的适合度成本延迟。这种现象对于性别决定位点等位基因较少的引入种群尤为相关，但在没有支持性遗传数据的本地种群中也不能被忽视。未来利用纸黄蜂种群来检验社会进化理论的研究应明确考虑二倍体雄性的潜在影响。
