Data from: Evolution of life history traits in geographically isolated populations of Vaejovis scorpions (Scorpiones: Vaejovidae)

Geographical isolation can over time accumulate life-history variation which can eventually lead to speciation. We used five species of Vaejovis scorpions that have been isolated from one another since the Pleistocene glaciation to identify if biogeographical patterns have allowed for the accumulation of life-history variation among species. Gravid females were captured and brought back to the lab until giving birth. Once offspring had begun to disperse, measurements of female size, reproductive investment, offspring size, offspring number, and variation in offspring size were recorded. Differences in how each species allocated energy to these variables were analysed utilizing path analysis and structural equation modelling. Female and offspring size, litter size, and total litter mass differed among species, but relative energetic investment did not. Most significant differences among species were not present after removing the effect of female size, indicating that female size is a major source of life-history variation. Path analyses indicated that there was no size–number trade-off within any species and that each species allocates energy toward total litter mass differently. Additionally, as offspring size increased, the variation in offspring mass decreased. These results show that each species allocates the same relative amount of energy in different ways. The variation seen could be a response to environmental variability or uncertainty, a product of maternal effects, or caused by the sufficient accumulation of genetic differences due to geographical isolation.地理隔离可随时间推移累积生活史变异，最终可能导致物种形成。我们选取了自更新世冰期以来便彼此隔离的5种瓦蝎属（Vaejovis）蝎子，以探究生物地理模式是否促成了物种种间生活史变异的累积。我们捕获怀卵雌蝎并带回实验室，直至其产下幼体。待幼体开始扩散后，记录了雌蝎体型、繁殖投入、幼体体型、幼体数量以及幼体体型变异等各项指标。我们利用通径分析（path analysis）与结构方程模型（structural equation modelling），分析了各物种在上述变量上的能量分配差异。结果显示，各物种间的雌蝎体型、幼体体型、胎仔数以及总窝质量均存在显著差异，但相对能量投入并无显著不同。在剔除雌蝎体型的影响后，多数物种间的显著差异便不复存在，这表明雌蝎体型是生活史变异的主要来源。通径分析结果表明，任一物种内部均未出现体型-胎仔数权衡，且各物种对总窝质量的能量分配策略各不相同。此外，幼体体型越大，其体重变异程度越低。上述结果显示，各物种的相对能量投入总量相同，但分配方式存在差异。观测到的生活史变异，可能是对环境多变性或不确定性的响应、母体效应的产物，或是地理隔离导致遗传差异充分累积的结果。