Gobin Bruno, Ito Fuminori, Billen Johan, Peeters Christian
Laboratory of Entomology, K.U. Leuven, Naamsestraat 59, 3000, Leuven, Belgium.
Naturwissenschaften. 2008 Nov;95(11):1041-8. doi: 10.1007/s00114-008-0420-x. Epub 2008 Aug 13.
Workers never mate in the large majority of ants, and they have usually lost the spermatheca, an organ specialized for long-term storage of sperm. Such 'non-sexual' workers are restricted to laying unfertilized eggs that give rise to males, and they cannot compete with the queens for the production of female offspring. In sharp contrast, workers in 200-300 species from phylogenetically basal subfamilies can reproduce sexually ('gamergates') because they retain a functional spermatheca like the queens. Importantly, 'non-sexual' workers in closely related species have a vestigial spermatheca. In this study, we compared the reservoir epithelium of 'sexual' workers to that of congeneric queens and 'non-sexual' workers using 21 species of Amblyoponinae, Ponerinae and Ectatomminae. We show that a pronounced thickening of the epithelium near the opening of the sperm duct is strictly associated with sexual reproduction in both castes. This is unlike 'non-sexual' workers in which this epithelium is always very thin, with few organelles; but all other structures remain intact. We discuss this evolutionary degeneration of the spermatheca and how it relates to behavioural or physiological modifications linked to mating. Our results help understand the loss of sexual reproduction by ant workers, a critical step in the extreme specialization of their phenotype.
在绝大多数蚂蚁中，工蚁从不交配，而且它们通常已经失去了受精囊，受精囊是一种专门用于长期储存精子的器官。这种“无性”工蚁只能产下未受精的卵，这些卵发育成雄蚁，它们无法与蚁后竞争产下雌性后代。与之形成鲜明对比的是，来自系统发育基部亚科的200 - 300个物种中的工蚁能够进行有性繁殖（“有性工蚁”），因为它们像蚁后一样保留了功能正常的受精囊。重要的是，亲缘关系相近物种中的“无性”工蚁有一个退化的受精囊。在这项研究中，我们使用了21种钝猛蚁亚科、猛蚁亚科和切叶蚁亚科的蚂蚁，将“有性”工蚁的储精上皮与同属的蚁后和“无性”工蚁的储精上皮进行了比较。我们发现，在两个蚁群中，精子管开口附近上皮的明显增厚都与有性繁殖密切相关。这与“无性”工蚁不同，“无性”工蚁的这种上皮总是非常薄，细胞器很少；但所有其他结构保持完整。我们讨论了受精囊的这种进化退化以及它与交配相关的行为或生理变化之间的关系。我们的结果有助于理解蚂蚁工蚁有性繁殖的丧失，这是它们表型极端特化过程中的关键一步。
