Male-driven reproductive and agonistic character displacement in darters and its implications for speciation in allopatry

Selection against hybridization can cause mating traits to diverge between species in sympatry via reproductive character displacement (RCD). Additionally, selection against interspecific fighting can cause aggressive traits to diverge between sympatric species via agonistic character displacement (ACD). By directly affecting conspecific recognition traits, RCD and ACD between species can also incidentally cause divergence in mating and fighting traits among populations within a species (termed cascade RCD and cascade ACD). Here, we demonstrate patterns consistent with male-driven RCD and ACD in two groups of darters (orangethroat darter clade Ceasia and rainbow darter Etheostoma caeruleum). In both groups, males that occur in sympatry (between Ceasia and E. caeruleum) have higher levels of preference for mating and fighting with conspecifics over heterospecifics than do males from allopatry. This is consistent with RCD and ACD. We also found patterns consistent with cascade RCD and cas...

对杂交的选择可通过生殖特征置换（reproductive character displacement, RCD）使同域分布的物种种间交配性状产生分化。此外，对种间争斗的选择可通过争斗特征置换（agonistic character displacement, ACD）导致同域物种种间的攻击性性状发生分化。由于二者直接作用于同种识别性状，物种种间的RCD与ACD还可间接引发一个物种种内不同种群间的交配与争斗性状分化，该过程被称为级联生殖特征置换和级联争斗特征置换（cascade RCD与cascade ACD）。本研究在两类镖鲈类群——橙喉镖鲈Ceasia支系与虹镖鲈（Etheostoma caeruleum）——中，观测到了符合雄性驱动的RCD与ACD的演化模式。在两类类群中，同域分布的雄性（即Ceasia支系与E. caeruleum的雄性）相较于异域分布的雄性，对同种个体的交配与争斗偏好程度均显著高于异种个体，这与RCD和ACD的理论预期一致。本研究同时发现了符合级联RCD与级联ACD的相关模式（原文未完成）