Québec-Océan and Centre Interuniversitaire de Recherche sur le Saumon Atlantique, Département de Biologie, Pavillon Alexandre-Vachon, Université Laval, Québec, QC, Canada G1V 0A6.
Proc Biol Sci. 2011 Jul 22;278(1715):2150-8. doi: 10.1098/rspb.2010.2045. Epub 2010 Dec 22.
Alternative reproductive tactics are ubiquitous in many species. Tactic expression often depends on whether an individual's condition surpasses thresholds that are responsible for activating particular developmental pathways. Two central goals in understanding the evolution of reproductive tactics are quantifying the extent to which thresholds are explained by additive genetic effects, and describing their covariation with condition-related traits. We monitored the development of early sexual maturation that leads to the sneaker reproductive tactic in Atlantic salmon (Salmo salar L.). We found evidence for additive genetic variance in the timing of sexual maturity (which is a measure of the surpassing of threshold values) and body-size traits. This suggests that selection can affect the patterns of sexual development by changing the timing of this event and/or body size. Significant levels of covariation between these traits also occurred, implying a potential for correlated responses to selection. Closer examination of genetic covariances suggests that the detected genetic variation is distributed along at least five directions of phenotypic variation. Our results show that the potential for evolution of the life-history traits constituting this reproductive phenotype is greatly influenced by their patterns of genetic covariance.
替代生殖策略在许多物种中普遍存在。策略表达通常取决于个体的状况是否超过了负责激活特定发育途径的阈值。理解生殖策略进化的两个核心目标是量化由加性遗传效应解释的阈值程度，并描述它们与与条件相关的特征的协变关系。我们监测了导致大西洋鲑（Salmo salar L.）偷偷繁殖策略的早期性成熟的发育情况。我们发现性成熟时机（这是衡量阈值值超过的指标）和体型特征的加性遗传方差的证据。这表明选择可以通过改变事件的时间和/或体型来影响性发育的模式。这些特征之间还存在显著的协变水平，这意味着对选择的相关反应的潜力。对遗传协方差的更仔细检查表明，检测到的遗传变异沿至少五个方向的表型变异分布。我们的研究结果表明，构成这种生殖表型的生活史特征的进化潜力受到其遗传协方差模式的极大影响。
