Assessing hybrid vigor using the thermal sensitivity of physiological trade-offs in tiger salamanders

Hybridization between species affects biodiversity and population sustainability in numerous ways, many of which depend on the fitness of the hybrid relative to the parental species. Hybrids can exhibit fitter phenotypes compared to the parental lineages, and this ‘hybrid vigor’ can then lead to the extinction of one or both parental lines.
In this study, we analyzed the relationship between water loss and gas exchange to compare physiological performance among three tiger salamander genotypes – the native California tiger salamander (CTS), the invasive barred tiger salamanders (BTS), and CTS x BTS hybrids across multiple temperatures (13.5°C, 20.5°C, and 23.5°C). We developed a new index of performance, the water-gas exchange ratio (WGER), which we define as the ratio of gas exchange to evaporative water loss (µL VO2/µL H2O). The ratio describes the ability of an organism to support energetically costly activities with high levels of gas exchange while simultaneously limiting water lo...

物种间的杂交可通过多种途径影响生物多样性与种群可持续性，其中多数效应取决于杂交后代相较于亲本物种的适应度。杂交个体可展现出优于亲本谱系的表型，此种“杂交优势”（hybrid vigor）可进而导致某一或两个亲本种群走向灭绝。
本研究针对三种虎螈基因型——本土加州虎螈（California Tiger Salamander, CTS）、入侵性带纹虎螈（Barred Tiger Salamander, BTS）以及CTS与BTS的杂交后代——在13.5℃、20.5℃与23.5℃三个温度条件下的生理表现展开对比分析，重点解析水分散失与气体交换之间的关联。
本研究构建了一项全新的生理性能指标：水气交换比（Water-Gas Exchange Ratio, WGER），将其定义为气体交换量与蒸发失水量的比值（μL VO₂/μL H₂O）。该比值可反映生物体在维持高水平气体交换以支撑高能耗生理活动的同时，限制水分散失的能力。