Data from: Additive genetic variance in polyandry enables its evolution, but polyandry is unlikely to evolve through sexy or good sperm processes

Polyandry is widespread despite its costs. The sexually selected sperm hypotheses (‘sexy’ and ‘good’ sperm) posit that sperm competition plays a role in the evolution of polyandry. Two poorly studied assumptions of these hypotheses are the presence of additive genetic variance in polyandry and sperm competitiveness. Using a quantitative genetic breeding design in a natural population of Drosophila melanogaster, we first established the potential for polyandry to respond to selection. We then investigated whether polyandry can evolve through sexually selected sperm processes. We measured lifetime polyandry and offensive sperm competitiveness (P2) while controlling for sampling variance due to male x male x female interactions. We also measured additive genetic variance in egg-to-adult viability and controlled for its effect on P2 estimates. Female lifetime polyandry showed significant and substantial additive genetic variance and evolvability. In contrast, we found little genetic variance or evolvability in P2 or egg-to-adult viability. Additive genetic variance in polyandry highlights its potential to respond to selection. However, the low levels of genetic variance in sperm competitiveness suggest the evolution of polyandry may not be driven by sexy sperm or good sperm processes.

尽管存在演化代价，一妻多夫制（polyandry）仍广泛分布。性选择精子假说（含“性感精子”与“优质精子”子假说）提出，精子竞争在一妻多夫制的演化进程中发挥作用。该假说存在两个尚未得到充分研究的前提假设：一妻多夫制与精子竞争力均存在加性遗传方差（additive genetic variance）。本研究以黑腹果蝇（Drosophila melanogaster）的自然种群为研究对象，采用数量遗传育种设计，首先验证了一妻多夫制对选择作出响应的演化潜力。随后，我们探究了一妻多夫制是否可通过性选择精子过程实现演化。研究中，我们测定了雌性终身一妻多夫水平与进攻性精子竞争力（P2），同时控制了由雄×雄×雌交互作用引发的抽样方差。此外，我们还测定了卵至成虫存活率的加性遗传方差，并控制其对P2估算值的影响。结果显示，雌性终身一妻多夫制存在显著且可观的加性遗传方差与可进化性。与之形成鲜明对比的是，我们在进攻性精子竞争力（P2）与卵至成虫存活率中几乎未检测到遗传方差或可进化性。一妻多夫制的加性遗传方差表明其具备响应选择的演化潜力，然而精子竞争力较低的遗传方差水平提示，一妻多夫制的演化可能并非由“性感精子”或“优质精子”过程所驱动。