Brown trout Salmo trutta is a potent global invader and its establishments have progressively altered physiologies, life-histories and niche-availabilities for native fish species. River impoundments further escalate its invasion potential. The Himalayan rivers however, stay uncharted for the effects of brown trout interactions with the native fish fauna. Snow trout Schizothorax richardsonii a Himalayan cold-water native, concerningly overlaps its range with brown trout. To understand its responses to invasion pressures, we investigated brown trout effects on the age and growth of snow trout populations in three rivers with varying levels of perturbation: (a) a dammed and (b) an undammed river with the invasive brown trout in comparison to (c) an undammed river without invasion pressures. We found sympatric snow trout in the undammed river to respond to brown trout invasion with fast life history responses, showing an early age-at-maturity (A₅₀ = 1.2 years) and fast growth with a higher growth constant (K = 0.40 yr⁻¹) and specific rate of linear growth across life. On the contrary, sympatric snow trout in the dammed river showed an explicitly slow life-history by maturing at a higher age (A₅₀ = 2.9 years) and a slow growth, with a lower growth constant (K = 0.26 yr⁻¹) and specific linear growth rates. Our findings suggest that, the snow trout appear to present stronger response to brown trout invasions when the river is unaltered and free from hydropower operations and damming. Further research is strongly warranted from other high-altitude Himalayan basins to delineate the variation in growth strategies exhibited by snow trout in sympatry with the invasives.

中文翻译：

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入侵的褐鳟 Salmo trutta 在喜马拉雅山的本地雪鳟 Schizothorax richardsonii 中诱导差异生长策略：未改变河流中的本地人是否更擅长选择入侵的挑战？

褐鳟Salmo trutta是一种强大的全球入侵者，其栖息地逐渐改变了本地鱼类物种的生理、生活史和生态位可用性。河流蓄水进一步升级了其入侵潜力。然而，喜马拉雅河流并未对褐鳟鱼与本地鱼类群落的相互作用产生影响。雪鳟Schizothorax richardsonii喜马拉雅冷水本地人，与褐鳟鱼的分布范围略有重叠。为了了解其对入侵压力的反应，我们研究了三条不同扰动水平的河流中褐鳟鱼对雪鳟鱼种群年龄和生长的影响：(a) 一条有坝的河流和 (b) 一条未筑坝的河流与入侵的褐鳟鱼相比(c) 一条没有入侵压力的未设坝的河流。我们发现未设坝河流中的同域雪鳟鱼以快速的生活史响应响应褐鳟鱼的入侵，表现出早熟（A ₅₀  = 1.2 年）和快速生长，具有较高的生长常数（K  = 0.40 yr ^{- 1}) 和整个生命的特定线性增长率。相反，大坝河流中的同域雪鳟鱼在较高年龄（A ₅₀  = 2.9 年）成熟时表现出明显缓慢的生活史，生长缓慢，生长常数较低（K  = 0.26 yr ^-1）和特定的线性增长率。我们的研究结果表明，当河流没有改变并且没有水电运营和筑坝时，雪鳟鱼似乎对褐鳟鱼的入侵表现出更强的反应。强烈需要从其他高海拔喜马拉雅盆地进行进一步的研究，以描绘与入侵者一致的雪鳟鱼生长策略的变化。