Data from: Life-history differences favor evolution of male dimorphism in competitive games

Many species exhibit two discrete male morphs: fighters and sneakers. Fighters are large and possess weapons but may mature slowly. Sneakers are small and have no weapons but can sneak matings and may mature quickly to start mating earlier in life than fighters. However, how differences in competitive ability and life history interact to determine male morph coexistence has not yet been investigated within a single framework. Here we integrate demography and game theory into a two-sex population model to study the evolution of strategies that result in the coexistence of fighters and sneakers. We incorporate differences in maturation time between the morphs and use a mating-probability matrix analogous to the classic hawk-dove game. Using adaptive dynamics, we show that male dimorphism evolves more easily in our model than in classic game theory approaches. Our results also revealed an interaction between life-history differences and sneaker competitiveness, which shows that demography and competitive games should be treated as interlinked mechanisms to understand the evolution of male dimorphism. Applying our approach to empirical data on bulb mites (Rhizoglyphus robini), coho salmon (Oncorhynchus kisutch), and bullhorned dung beetles (Onthophagus taurus) indicates that observed occurrences of male dimorphism are in general agreement with model predictions.

诸多物种均存在两种离散的雄性形态：格斗型（fighters）与投机型（sneakers）。格斗型个体体型较大且配备武器，但成熟速度较慢；投机型个体体型小巧且无武器，却可通过偷袭完成交配，且成熟速度更快，能够比格斗型个体更早开启交配行为。然而，目前尚未有统一框架来探究竞争能力与生活史特征的差异如何共同作用，决定雄性形态的共存格局。本研究将种群统计学与博弈论相结合，构建双性种群模型，以探究促成格斗型与投机型共存的策略演化机制。研究纳入了不同形态间的成熟时间差异，并采用类似于经典鹰鸽博弈的交配概率矩阵。借助适应性动力学分析，本研究发现相较于经典博弈论模型，本模型中雄性二态性更易演化形成。研究结果还揭示了生活史差异与投机型竞争力之间的交互作用，表明要理解雄性二态性的演化，需将种群统计学与竞争博弈视为相互关联的机制。将本研究方法应用于罗宾根螨（Rhizoglyphus robini）、银大麻哈鱼（Oncorhynchus kisutch）以及双角蜣螂（Onthophagus taurus）的实证数据后发现，观测到的雄性二态性出现情况与模型预测总体一致。