Travers L M, Simmons L W, Garcia-Gonzalez F
Centre for Evolutionary Biology, School of Animal Biology (M092), The University of Western Australia, Crawley, WA, Australia.
Doñana Biological Station, Spanish Research Council CSIC, Sevilla, Spain.
J Evol Biol. 2016 May;29(5):916-28. doi: 10.1111/jeb.12834. Epub 2016 Feb 6.
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 × male × 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 that the evolution of polyandry may not be driven by sexy sperm or good sperm processes.
一妻多夫现象虽然存在代价，但却广泛存在。性选择精子假说（“性感”精子和“优质”精子）认为精子竞争在一妻多夫制的进化中发挥了作用。这些假说中有两个研究较少的假设，即一妻多夫制中存在加性遗传方差以及精子竞争力。我们在黑腹果蝇的自然种群中采用定量遗传育种设计，首先确定了一妻多夫制对选择作出反应的潜力。然后，我们研究了一妻多夫制是否能通过性选择精子过程进化。我们测量了终生一妻多夫制和进攻性精子竞争力（P2），同时控制了由于雄×雄×雌相互作用导致的抽样方差。我们还测量了卵到成虫存活率的加性遗传方差，并控制其对P2估计值的影响。雌性终生一妻多夫制表现出显著且大量的加性遗传方差和进化潜力。相比之下，我们发现P2或卵到成虫存活率的遗传方差或进化潜力很小。一妻多夫制中的加性遗传方差突出了其对选择作出反应的潜力。然而，精子竞争力的低水平遗传方差表明，一妻多夫制的进化可能不是由性感精子或优质精子过程驱动的。
