The geographic mosaic of arms race coevolution is closely matched to prey population structure

Reciprocal adaptation is the hallmark of arms race coevolution. Local coadaptation between natural enemies should generate a geographic mosaic pattern where both species have roughly matched abilities across their shared range. However, mosaic variation in ecologically relevant traits can also arise from processes unrelated to reciprocal selection, such as population structure or local environmental conditions. We tested whether these alternative processes can account for trait variation in the geographic mosaic of arms race coevolution between resistant garter snakes (Thamnophis sirtalis) and toxic newts (Taricha granulosa). We found that predator resistance and prey toxin levels are functionally matched in co-occurring populations, suggesting that mosaic variation in the armaments of both species results from the local pressures of reciprocal selection. By the same token, phenotypic and genetic variation in snake resistance deviates from neutral expectations of population genetic diff...

相互适应是军备竞赛型协同进化的标志性特征。天敌间的局部共适应理应形成地理镶嵌格局，使两个物种在其共同分布范围内的适配能力大致匹配。然而，生态相关性状的镶嵌变异也可由与相互选择无关的过程引发，例如种群结构或局域环境条件。我们检验了这些非协同选择过程能否解释抗毒束带蛇（Thamnophis sirtalis）与有毒螈（Taricha granulosa）之间军备竞赛型协同进化地理镶嵌格局中的性状变异。研究发现，同域种群中捕食者抗性与猎物毒素水平存在功能匹配关系，这表明两个物种的军备性状的镶嵌变异源于相互选择的局域选择压力。同理，蛇类抗性的表型与遗传变异偏离了种群遗传分化的中性预期……