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：战斗型与偷袭型。战斗型雄性体型硕大且特化出武器结构，但成熟进程较为缓慢；偷袭型雄性体型小巧且无相关武器，却可通过偷袭策略完成交配，且成熟速度更快，能够比战斗型雄性更早开展交配活动。然而，竞争能力与生活史特征的差异如何相互作用，进而决定雄性形态的共存格局，目前尚未在统一的理论框架内得到系统研究。本研究将种群统计学与博弈论整合至双性种群模型之中，旨在探究能够促成战斗型与偷袭型雄性共存的策略演化机制。我们纳入了不同形态型间的成熟时间差异，并采用与经典鹰鸽博弈（hawk-dove game）相似的交配概率矩阵。通过适应性动力学（adaptive dynamics）分析，我们发现相较于经典博弈论模型，本模型中雄性二态性的演化更易发生。研究结果同时揭示了生活史差异与偷袭型雄性竞争力之间的相互作用关系，这表明种群统计学与竞争博弈机制应被视为相互关联的整体，以解析雄性二态性的演化过程。将本研究方法应用于罗宾根螨（Rhizoglyphus robini）、银鲑（Oncorhynchus kisutch）以及牛角粪金龟（Onthophagus taurus）的实证数据后，结果显示观测到的雄性二态性出现情况与模型预测结果总体一致。