Kervinen Matti, Lebigre Christophe, Alatalo Rauno V, Siitari Heli, Soulsbury Carl D
Department of Biological and Environmental Science, P.O. Box 35, University of Jyväskylä, 40014 Jyväskylä, Finland.
Am Nat. 2015 Jan;185(1):13-27. doi: 10.1086/679012. Epub 2014 Nov 19.
Age is a major factor explaining variation in life-history traits among individuals with typical patterns of increasing trait values early in life, maximum trait expression, and senescence. However, age-dependent variation in the expressions of sexually selected traits has received less attention, although such variation underpins differences in male competitive abilities and female preference, which are central to sexual selection. In contrast to previous studies focusing on single traits, we used repeated measures of seven sexually selected morphological and behavioral traits in male black grouse (Tetrao tetrix) to quantify the effects of age and life span on their expressions and quantified this variation in relation to male reproductive effort. Trait expression increased with age, but long-lived males had a slower increase and delayed maxima in trait values compared with short-lived males. There was evidence of terminal investment (increasing trait values during the last breeding season) in some traits and senescence in all traits. These trait dynamics were largely explained by the timing of male peak lekking effort. This study shows that fully understanding the variation in sexually selected traits and fitness benefits associated with sexual selection requires accounting for the complex interaction among individual age, life span, and the timing of individuals' investment in reproduction.
年龄是解释具有典型生活史特征模式的个体间生活史特征差异的主要因素，这些特征模式包括生命早期特征值增加、特征表达达到最大值以及衰老。然而，性选择特征表达的年龄依赖性差异受到的关注较少，尽管这种差异是雄性竞争能力和雌性偏好差异的基础，而这些差异对于性选择至关重要。与以往关注单一特征的研究不同，我们对雄性黑琴鸡（Tetrao tetrix）的七种性选择形态和行为特征进行了重复测量，以量化年龄和寿命对其表达的影响，并将这种差异与雄性繁殖努力相关联进行量化。特征表达随年龄增加，但与寿命短的雄性相比，寿命长的雄性特征值增加较慢且最大值出现延迟。在某些特征中存在终端投资（在最后一个繁殖季节特征值增加）的证据，并且所有特征都存在衰老现象。这些特征动态在很大程度上由雄性求偶场炫耀努力的峰值时间所解释。这项研究表明，要全面理解性选择特征的差异以及与性选择相关的适应性益处，需要考虑个体年龄、寿命以及个体繁殖投资时间之间的复杂相互作用。
