Gamble Madilyn M, Calsbeek Ryan G
Graduate Program in Ecology, Evolution, Ecosystems, and Society Dartmouth College Hanover NH USA.
Evol Appl. 2021 Sep 28;14(11):2576-2590. doi: 10.1111/eva.13292. eCollection 2021 Nov.
Intralocus sexual conflict, which arises when the same trait has different fitness optima in males and females, reduces population growth rates. Recently, evolutionary biologists have recognized that intralocus conflict can occur between morphs or reproductive tactics within a sex and that intralocus tactical conflict might constrain tactical dimorphism and population growth rates just as intralocus sexual conflict constrains sexual dimorphism and population growth rates. However, research has only recently focused on sexual and tactical intralocus conflict simultaneously, and there is no formal theory connecting the two. We present a graphical model of how tactical and sexual conflict over the same trait could constrain both sexual and tactical dimorphisms. We then use Coho salmon (), an important species currently protected under the Endangered Species Act, to investigate the possibility of simultaneous sexual and tactical conflict. Larger Coho males gain access to females through fighting while smaller males are favored through sneaking tactics, and female reproductive success is positively correlated with length. We tested for antagonistic selection on length at maturity among sexes and tactics and then used parent-offspring regression to calculate sex- and tactic-specific heritabilities to determine whether and where intralocus conflict exists. Selection on length varied in intensity and form among tactics and years. Length was heritable between dams and daughters ( ± 95% CI = 0.361 ± 0.252) and between fighter males and their fighter sons (0.867 ± 0.312), but no other heritabilities differed significantly from zero. The lack of intertactical heritabilities in this system, combined with similar selection on length among tactics, suggests the absence of intralocus conflict between sexes and among tactics, allowing for the evolution of sexual and tactical dimorphisms. Our results suggest that Coho salmon populations are unlikely to be constrained by intralocus conflict or artificial selection on male tactic.
基因座内的性冲突是指同一性状在雄性和雌性中具有不同的适合度最优值时所产生的冲突，它会降低种群增长率。最近，进化生物学家已经认识到，基因座内冲突可能发生在同一性别内的不同形态或繁殖策略之间，并且基因座内的策略冲突可能会像基因座内的性冲突限制两性异形和种群增长率一样，限制策略二态性和种群增长率。然而，直到最近研究才同时聚焦于性冲突和策略性基因座内冲突，并且尚无将两者联系起来的正式理论。我们提出了一个图形模型，展示了针对同一性状的策略性冲突和性冲突如何可能同时限制两性异形和策略二态性。然后，我们利用银大麻哈鱼（目前是《濒危物种法》保护的重要物种）来研究同时存在性冲突和策略性冲突的可能性。体型较大的银大麻哈鱼雄性通过争斗获得与雌性交配的机会，而体型较小的雄性则通过偷袭策略获得青睐，并且雌性的繁殖成功率与体长呈正相关。我们测试了不同性别和策略在成熟体长上的拮抗选择，然后利用亲子回归来计算特定性别和策略的遗传力，以确定基因座内冲突是否存在以及存在于何处。在不同策略和年份中，对体长的选择在强度和形式上有所不同。体长在雌鱼和雌鱼后代之间具有遗传性（±95%CI = 0.361 ± 0.252），在争斗型雄性与其争斗型儿子之间也具有遗传性（0.867 ± 0.312），但没有其他遗传力显著不同于零。该系统中缺乏策略间的遗传力，再加上不同策略对体长的选择相似，这表明在性别之间和策略之间不存在基因座内冲突，从而使得两性异形和策略二态性得以进化。我们的结果表明，银大麻哈鱼种群不太可能受到基因座内冲突或对雄性策略的人工选择的限制。
