The neglected sex: male reproductive interests and sexual selection in social insects

蚂蚁和其他群居的膜翅目昆虫展示了独特的性生活，这可能会验证性选择理论的预测。例如，雌性在交配之前会产生大量的不育工蜂，并且在以后的生活中不会再交配，这至少在理论上使得雄性试图以牺牲雌性寿命为代价来操纵雌性生育能力的任何尝试都是徒劳的，并将性别冲突降至最低。此外，由于精子的限制，雄性应该对与其交配的雌性极其挑剔。尽管有这些不寻常和有趣的特征，但群居昆虫的交配显然鲜为人知。在我们的项目中，我们已经开始研究和描述蚂蚁细胸蚁及其近缘物种繁殖生物学的各个方面。结合化学、遗传学、组织学和行为学的方法，我们发现：a)男性和女性至少是挑剔的，因为他们至少避免与相关的个体交配，他们可能通过两性角质层碳氢化合物模式的群体特异性认识到这一点；b)雌性可能有选择精子的能力，因为雄性在交配时将精子转移到雌性的法氏囊交界处，在那里它通过精囊导管中的极窄的收缩非常缓慢地迁移到受精囊；c)交配过程中雄性传递的凝胶状精囊防止精子从雌性的阴道丢失，但不阻止与其他雄性交配；d)雄性附腺在物种中保存，这与没有性别冲突是一致的，e)不同物种之间精子细胞的长度不同，推测精子竞争的程度也不同。在这个项目的最后阶段，我们打算完成最近开始的对副腺分泌物中发现的蛋白质的分析，使用基于聚合酶链式反应的抑制消减杂交。这将有助于更多地了解雄性在交配过程中转移的蛋白质的性质。

Ants and other social Hymenoptera exhibit a unique sex life which might allow testing predictions from sexual selection theory. For example, females produce large numbers of sterile workers before rearing sexuals and do not re-mate later in life, which at least in theory makes any male attempts to manipulate female fecundity at the cost of female longevity futile and minimizes sexual conflict.Furthermore, because of sperm limitation, males should be extremely choosy about the female they mate with.Despite of these unusual and interesting features, mating in social insects is remarkably littleunderstood. In our project we have set out to examine and describe various aspects of thereproductive biology of the ant Leptothorax gredleriand related species. Combining chemical, genetic, histological, and behavioural approaches we documented thata) male and female sexuals are choosy at least in that they avoid mating with related individuals, which they presumably recognize through the colony-specificity of cuticular hydrocarbon patterns in both sexes, b) females are presumably capable of sperm selection, because males transfer sperm during copulation into the female's bursa copulatrix, from where it very slowly migrates into the spermatheca through an extremely narrow constriction in the spermathecal duct, c) the gelatinous spermatophore transmitted by males during copulation prevents the loss of sperm from the female's vagina but does not prevent mating with other males, d) male accessory gland proteins are conserved among species, which is in accordance with the lack of sexual conflict, e) the length of sperm cells varies between different species with the presumed extent of sperm competition. In a last phase of this project we intend to complete a recently begun analysis of the proteins found in the accessory gland secretions, using PCR-based suppression subtractive hybridization. This shall help to learn more about the nature of the proteins that the male transfers during copulation.