Physiological traits are key determinants of species success in any given environment. Competing metabolic demands can influence success by limiting the available scope for aerobically-demanding activities, including reproduction and dispersal. The present study investigated whether the aerobic performance of Gambusia holbrooki, one of the most invasive species in the world, was affected by the embryonic demands of pregnancy and whether these demands were compounded in a hypoxic environment. To quantify these effects, we measured the resting metabolic rate (RMR) and critical swimming speed (U_crit) of wild-caught adult mosquitofish in saturated oxygen conditions, and following chronic exposure to hypoxic or hyperoxic water. Contrary to expectations, the RMR and U_crit of gravid females was equal to that of non-gravid females and males, once the significant effects of body mass on these traits was accounted for. Whilst the exposure studies demonstrated that RMR changes subject to oxygen availability, overall aerobic performance does not. These findings suggest that mosquitofish metabolism is adapted for continued reproductive function and dispersal in low oxygen environments, which are essential for establishing and replenishment of populations. The ability of this species to tolerate hypoxia may confer a competitive advantage relative to native species, especially in disturbed lentic environments where prolonged periods of hypoxia are more common. Given their live-bearing mode of reproduction and resilience to the metabolic demands of reproduction, even in low oxygen conditions, we suggest that the physiology of female mosquitofish is a significant contributor to the invasion success and persistence of the species.

生理特性是任何给定环境中物种成功的关键决定因素。竞争性的新陈代谢需求可以通过限制有氧要求活动的可用范围（包括繁殖和分散）来影响成功。本研究调查了世界上侵入性最强的物种之一的Gambusia holbrooki的有氧性能是否受到怀孕的胚胎需求的影响，以及这些需求在低氧环境中是否复合。为了量化这些影响，我们测量了饱和氧气条件下以及长期暴露于低氧或高氧水中的野生捕捞成年蚊的静息代谢率（RMR）和临界游泳速度（U _crit）。与预期相反，RMR和超_临界一旦考虑到体重对这些性状的显着影响，妊娠女性的体重等于非非妊娠女性和男性。尽管接触研究表明RMR随氧气供应量而变化，但总体有氧性能却没有变化。这些发现表明，蚊鱼的代谢适应于低氧环境中的持续生殖功能和扩散，这对于建立和补充种群至关重要。相对于本地物种，该物种耐受缺氧的能力可能赋予竞争优势，尤其是在长期缺氧时间较为普遍的扰乱的透镜状环境中。考虑到它们的活体繁殖方式以及即使在低氧条件下也能抵抗繁殖的代谢需求，