Ecology Group, Allan Wilson Center for Molecular Ecology and Evolution, INR, Massey University, Palmerston North, New Zealand.
Mol Ecol. 2010 Mar;19(6):1227-38. doi: 10.1111/j.1365-294X.2010.04542.x. Epub 2010 Feb 15.
Worldwide, parthenogenetic reproduction has evolved many times in the stick insects (Phasmatidae). Many parthenogenetic stick insects show the distribution pattern known as geographic parthenogenesis, in that they occupy habitats that are at higher altitude or latitude compared with their sexual relatives. Although it is often assumed that, in the short term, parthenogenetic populations will have a reproductive advantage over sexual populations; this is not necessarily the case. We present data on the distribution and evolutionary relationships of sexual and asexual populations of the New Zealand stick insect, Clitarchus hookeri. Males are common in the northern half of the species' range but rare or absent elsewhere, and we found that most C. hookeri from putative-parthenogenetic populations share a common ancestor. Female stick insects from bisexual populations of Clitarchus hookeri are capable of parthenogenetic reproduction, but those insects from putative-parthenogenetic populations produced few offspring via sexual reproduction when males were available. We found similar fertility (hatching success) in mated and virgin females. Mated females produce equal numbers of male and female offspring, with most hatching about 9-16 weeks after laying. In contrast, most eggs from unmated females took longer to hatch (21-23 weeks), and most offspring were female. It appears that all C. hookeri females are capable of parthenogenetic reproduction, and thus could benefit from the numerical advantage this yields. Nevertheless, our phylogeographic evidence shows that the majority of all-female populations over a wide geographic area originate from a single loss of sexual reproduction.
在全世界范围内，孤雌生殖已经在竹节虫（Phasmatidae）中多次进化。许多孤雌生殖的竹节虫表现出了地理上的孤雌生殖分布模式，它们的栖息地海拔或纬度比其有性亲属的栖息地更高。尽管人们通常认为，在短期内，孤雌生殖种群将比有性生殖种群具有生殖优势，但情况并非总是如此。我们提供了有关新西兰竹节虫 Clitarchus hookeri 的有性和无性种群的分布和进化关系的数据。在该物种分布范围的北部，雄性较为常见，但在其他地方则较为稀少或不存在，而且我们发现，大多数来自假定的孤雌生殖种群的 C. hookeri 具有共同的祖先。来自 Clitarchus hookeri 两性种群的雌性竹节虫能够进行孤雌生殖，但当雄性存在时，来自假定的孤雌生殖种群的雌性竹节虫通过有性生殖产生的后代很少。我们发现有交配和未交配的雌性都具有相似的生育能力（孵化成功率）。交配后的雌性会产生等量的雄性和雌性后代，大多数在产卵后 9-16 周孵化。相比之下，大多数未交配雌性的卵需要更长的时间孵化（21-23 周），并且大多数后代为雌性。似乎所有的 C. hookeri 雌性都能够进行孤雌生殖，因此可以从这种生殖方式带来的数量优势中受益。然而，我们的系统地理学证据表明，在广泛的地理区域内，大多数全雌性种群都源于单一的有性生殖丧失。
