Data from: Harvesting changes mating behavior in European lobster

Removing individuals from a wild population can affect the availability of prospective mates and the outcome of competitive interactions, with subsequent effects on mating patterns and sexual selection. Consequently, the rate of harvest-induced evolution is predicted to be strongly dependent on the strength and dynamics of sexual selection yet, there is limited empirical knowledge on the interplay between selective harvesting and the mating systems of exploited species. In this study, we used genetic parentage assignment to compare mating patterns of the highly valued and overexploited European lobster (Homarus gammarus) in a designated lobster reserve and nearby fished area in Southern Norway. In the area open to fishing, the fishery is regulated by a closed season, a minimum legal size and a ban on the harvest of egg-bearing females. Due to the differences in size and sex-specific fishing mortality between the two areas, males and females are of approximately equal average size in the fished area, whereas males tend to be larger in the reserve. Our results show that females would mate with males larger than their own body size, but the relative size difference was significantly larger in the reserve. Sexual selection acted positively on both body size and claw size in males in the reserve, while it was non-significant in fished areas. This strongly suggests that size truncation of males by fishing reduces the variability of traits that sexual selection acts upon. If fisheries continue to target large individuals (particularly males) with higher relative reproductive success, the weakening of sexual selection will likely accelerate fisheries-induced evolution towards smaller body size.

从野生种群中移除个体，可能会影响潜在配偶的可获得性与竞争互动的结局，并进一步对交配模式与性选择（sexual selection）产生连锁效应。据此，有预测指出，捕捞诱导的进化（harvest-induced evolution）速率将极大程度上取决于性选择的强度与动态，但目前针对选择性捕捞与被开发物种种群交配系统之间相互作用的实证研究仍较为匮乏。本研究采用遗传亲权鉴定（genetic parentage assignment）技术，对比分析了挪威南部某指定龙虾保护区与邻近捕捞区内的高经济价值且过度开发的欧洲龙虾（*Homarus gammarus*）的交配模式。在开放捕捞的区域，渔业受禁渔期、最小法定体长以及抱卵雌性个体捕捞禁令的管制。由于两个区域在体长与性别特异性捕捞死亡率上存在差异，捕捞区域内雌雄个体的平均体长大致相当，而保护区内雄性个体的平均体长显著大于雌性。研究结果显示，雌性个体倾向于选择体长大于自身的雄性作为配偶，但保护区内雌雄间的相对体长差异显著更大。保护区内雄性的体长与螯长均受到性选择的正向作用，而捕捞区内该作用并不显著。这一结果有力表明，捕捞活动对雄性个体的体长截除效应，会削弱性选择所作用的性状变异度。若渔业持续以相对繁殖成功率更高的大型个体（尤其是雄性）为捕捞目标，性选择的弱化将可能加速捕捞诱导的小型化进化进程。