Data from: Locomotor endurance predicts differences in realized dispersal between sympatric sexual and unisexual salamanders

Dispersal is the central mechanism that determines connectivity between populations yet few studies connect the mechanisms of movement with realized dispersal in natural populations. To make such a link, we assessed how physiological variation among individuals predicted dispersal in natural populations of unisexual (all-female) and sexual Ambystoma salamanders on the same fragmented landscape in Ohio. Specifically, we assessed variation in a trait that influences long-distance animal movement (locomotor endurance) and determined whether variation in endurance matched patterns of realized dispersal assessed using genetic assignment tests. A possible mechanism for why unisexuals would have lower locomotor endurance than a sympatric sexual species (Ambystoma texanum) is the potential energetic cost of evolutionarily mismatched mitochondrial and nuclear genomes within polyploid unisexuals. We found that sexuals walked four times farther than unisexuals during treadmill endurance trials that mimic the locomotor endurance required for dispersal. We then applied landscape genetic methods to identify dispersed adults and quantify realized dispersal. We show that the differences in locomotor endurance between unisexual and sexual salamanders scale to realized dispersal: dispersing sexual individuals travelled approximately twice the distance between presumed natal wetlands and the site of capture compared to dispersing unisexuals. This study links variation in individual performance in terms of endurance with realized dispersal in the field and suggests a potential mechanism (physiological limitation due to mitonuclear mismatch) for the reduced endurance of unisexual individuals relative to sexual individuals although we discuss other possible explanations. The differences in dispersal between these two types of salamanders also informs our understanding of sexual/unisexual coexistence by suggesting that unisexuals are at a competitive disadvantage in terms of colonization ability under a extinction-colonization model of coexistence.扩散是决定种群间连通性的核心机制，但目前鲜有研究将运动机制与自然种群中的实际扩散建立关联。为建立此类关联，我们评估了个体间的生理变异如何预测俄亥俄州同一破碎化景观中，单性（全雌）与有性钝口螈属（Ambystoma）蝾螈自然种群的扩散情况。 具体而言，我们测定了影响动物长距离移动的性状——运动耐力（locomotor endurance）——的变异，并验证了耐力变异是否与通过遗传归属检测（genetic assignment tests）评估的实际扩散模式相匹配。相较于同域分布的有性物种德克萨斯钝口螈（Ambystoma texanum），单性类群运动耐力更低的潜在机制之一，可能是多倍体单性类群中进化错配的线粒体与核基因组所带来的潜在能量成本。 我们发现，在模拟扩散所需运动耐力的跑台耐力试验中，有性个体的行走距离是单性个体的四倍。 随后我们运用景观遗传学方法（landscape genetic methods）鉴定扩散个体并量化实际扩散水平。研究结果显示，单性与有性钝口螈的运动耐力差异可对应至实际扩散水平：相较于扩散的单性个体，扩散的有性个体在推测的出生湿地与捕获位点间的移动距离约为其两倍。 本研究将个体耐力表现的变异与野外实际扩散建立关联，并提出了相较于有性个体，单性个体耐力降低的潜在机制——线粒体-核基因组错配导致的生理限制，同时我们也讨论了其他可能的解释。 这两类蝾螈的扩散差异还增进了我们对有性/单性共存的理解：在灭绝-定殖共存模型（extinction-colonization model）框架下，该结果表明单性类群在定殖能力上处于竞争劣势。