Data from: Random sperm use and genetic effects on worker caste fate in Atta colombica leaf-cutting ants

Sperm competition can produce fascinating adaptations with far-reaching
evolutionary consequences. Social taxa make particularly interesting
models, because the outcome of sexual selection determines the genetic
composition of groups, with attendant sociobiological consequences. Here,
we use molecular tools to uncover some of the mechanisms and consequences
of sperm competition in the leaf-cutting ant Atta colombica, a species
with extreme worker size polymorphism. Competitive PCR allowed
quantification of the relative numbers of sperm stored by queens from
different males, and offspring genotyping revealed how sperm number
translated into paternity of eggs and adult workers. We demonstrate that
fertilisation success is directly related to sperm numbers, that stored
sperm are well mixed and that egg paternity is constant over time.
Moreover, worker size was found to have a considerable genetic component,
despite expectations that genetic effects on caste fate should be reduced
in species with a low degree of polyandry. Our data suggest that sexual
conflict over paternity is largely resolved by the lifetime commitment
between mates generated by long-term sperm storage, and show that genetic
variation for caste can persist in societies with comparatively high
relatedness.

精子竞争可催生具有深远进化意义的精妙适应性特征，并带来广泛的演化后果。社会类群为此提供了尤为理想的研究模型，这是因为性选择的结果决定了群体的遗传构成，并伴随产生相应的社会生物学效应。本研究借助分子生物学手段，对具有极端工蚁体型多态性的哥伦比亚切叶蚁（Atta colombica）的精子竞争机制与效应展开探究。通过竞争性聚合酶链式反应（competitive PCR），可定量分析蚁后储存的不同雄性个体精子的相对数量；而对后代进行基因分型，则能揭示精子数量如何转化为卵与成年工蚁的父权比例。本研究证实，受精成功率与精子数量直接相关，储存的精子混合均匀，且卵的父权比例随时间保持稳定。此外，尽管学界此前预期，在多雄交配程度较低的物种中，遗传对品级分化的影响应有所减弱，但本研究发现工蚁体型存在显著的遗传基础。研究数据表明，由长期精子储存所形成的配偶间终身绑定关系，在很大程度上化解了父权相关的性冲突；同时也证实，在亲缘度相对较高的蚁群社会中，品级相关的遗传变异仍可得以保留。