Réale D, Festa-Bianchet M
Département de Biologie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada.
Heredity (Edinb). 2000 Dec;85(Pt 6):593-603. doi: 10.1046/j.1365-2540.2000.00795.x.
Quantitative genetic studies of life-history traits in wild populations are very rare, yet variance/covariance estimates of these traits are crucial to understanding the evolution of reproductive strategies. We estimated heritabilities (h2) of several life-history traits (longevity, age and mass at primiparity, and reproductive traits) in two bighorn sheep (Ovis canadensis) populations, and both phenotypic (rP) and genetic (rA) correlations between life-history traits in one population. We included adult mass in our analyses because it is related to several life-history traits. We used the mother-daughter regression method and resampling tests based on data from long-term monitoring of marked females. Contrary to the theoretical prediction of low heritability for fitness-related traits, heritability estimates in the Ram Mountain population ranged from 0.02 to 0.81 (mean of 0.52), and several were different from zero. Coefficients of variation tend to support the hypothesis of a higher environmental influence on life-history traits. In contrast, at Sheep River we found low heritabilities of life-history traits. Phenotypic correlations varied between -0.09 and 0.95. Several genetic correlations were strong, particularly for different reproductive traits that are functionally related, and ranged from -0.34 to 1.71. Overall, genetic and phenotypic correlations between the same variables were similar in magnitude and direction. We found no phenotypic or genetic correlations suggesting trade-offs among life-history traits. Bighorn sheep may not form the large, outbred populations at equilibrium that are assumed by both Fisher's fundamental theorem and by theories predicting antagonistic pleiotropy between life-history traits. Alternatively, the absence of negative genetic correlations may result from genetic variation in ability to acquire resources or from novel environmental conditions existing during the study period.
对野生种群生活史特征进行的数量遗传学研究非常罕见，然而这些特征的方差/协方差估计对于理解生殖策略的进化至关重要。我们估计了两个大角羊（加拿大盘羊）种群中几个生活史特征（寿命、初产年龄和体重以及生殖特征）的遗传力（h2），以及一个种群中生活史特征之间的表型（rP）和遗传（rA）相关性。我们在分析中纳入了成年体重，因为它与几个生活史特征相关。我们使用母女回归法和基于对有标记雌性长期监测数据的重采样检验。与 fitness 相关性状低遗传力的理论预测相反，在拉姆山种群中，遗传力估计值范围为 0.02 至 0.81（平均为 0.52），其中几个不为零。变异系数倾向于支持对生活史特征环境影响更大的假设。相比之下，在羊河我们发现生活史特征的遗传力较低。表型相关性在 -0.09 至 0.95 之间变化。几个遗传相关性很强，特别是对于功能相关的不同生殖特征，范围从 -0.34 至 1.71。总体而言，相同变量之间的遗传和表型相关性在大小和方向上相似。我们没有发现表明生活史特征之间存在权衡的表型或遗传相关性。大角羊可能没有形成费希尔基本定理以及预测生活史特征之间拮抗多效性的理论所假设的处于平衡状态的大型远交种群。或者，缺乏负遗传相关性可能是由于获取资源能力的遗传变异或研究期间存在的新环境条件所致。
