Lewis Jason A, Pitcher Trevor E
Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada.
Great Lakes Institute for Environmental Research, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada; Department of Biological Sciences, University of Windsor, 401 Sunset Avenue, Windsor, Ontario, N9B 3P4, Canada.
Theriogenology. 2017 Apr 1;92:24-29. doi: 10.1016/j.theriogenology.2016.12.032. Epub 2016 Dec 26.
Sperm competition is prevalent and intense in many animal mating systems, and is a major force driving evolution of such mating systems. The objective of this study was to determine the effect of seminal plasma on sperm velocity of male Chinook salmon (Onchorhynchus tshawytscha), which possesses a mating system with male alternative reproductive tactics and intense sperm competition. Male Chinook salmon either adopt a small, precocious sneaking tactic (jack) or a large, dominant tactic (hooknose). To test whether the seminal plasma can effect sperm velocity amongst sperm competitors, two experiments were done whereby males were paired based upon the alternative tactic each male adopted, with the first experiment consisting of jack-hooknose pairs (N = 16) and the second experiment consisting of jack-jack and hooknose-hooknose pairs (N = 12 and 14, respectively). Within each pair, milt of each male was manipulated such that seminal plasma was removed and swapped between the males in each pair and sperm velocity was measured. Jack seminal plasma caused a significant decrease (∼11.9%) in hooknose sperm velocity while causing a significant increase in jack sperm velocity (∼7%), while alternatively, hooknose seminal plasma had no affect on sperm velocity of jack or other hooknose males. This study shows that rival seminal plasma may affect the outcome of sperm competition between males; males adopting a sneaking tactic, that spawn in a disadvantageous mating position, may be able to compensate for this deficit by being more competitive through the effects of their seminal plasma on their competitor's sperm velocity.
精子竞争在许多动物交配系统中普遍且激烈，是推动此类交配系统进化的主要力量。本研究的目的是确定精浆对雄性奇努克鲑（Onchorhynchus tshawytscha）精子速度的影响，奇努克鲑具有雄性替代生殖策略和激烈精子竞争的交配系统。雄性奇努克鲑要么采用小型早熟的偷配策略（矮雄），要么采用大型占主导地位的策略（钩鼻雄）。为了测试精浆是否会影响精子竞争者之间的精子速度，进行了两项实验，根据每个雄性采用的替代策略将雄性配对，第一个实验由矮雄 - 钩鼻雄对组成（N = 16），第二个实验由矮雄 - 矮雄对和钩鼻雄 - 钩鼻雄对组成（分别为N = 12和14）。在每对中，对每个雄性的精液进行处理，去除精浆并在每对雄性之间交换，然后测量精子速度。矮雄的精浆导致钩鼻雄精子速度显著降低（约11.9%），同时使矮雄精子速度显著增加（约7%），而相反，钩鼻雄的精浆对矮雄或其他钩鼻雄的精子速度没有影响。这项研究表明，竞争对手的精浆可能会影响雄性之间精子竞争的结果；采用偷配策略、在不利交配位置产卵的雄性，可能能够通过其精浆对竞争对手精子速度的影响而更具竞争力，从而弥补这一劣势。
