BACKGROUND In eastern North America two common colour morphs exist in most populations of redback salamanders (Plethodon cinereus). Previous studies have indicated that the different morphs may be adapted to different thermal niches and the morphological variation has been linked to standard metabolic rate at 15 degrees C in one population of P. cinereus. It has therefore been hypothesized that a correlated response to selection on metabolic rate across thermal niches maintains the colour polymorphism in P. cinereus. This study tests that hypothesis. RESULTS We found that the two colour morphs do sometimes differ in their maintenance metabolic rate (MMR) profiles, but that the pattern is not consistent across populations or seasons. We also found that when MMR profiles differ between morphs those differences do not indicate that distinct niches exist. Field censuses showed that the two colour morphs are sometimes found at different substrate temperatures and that this difference is also dependent on census location and season. CONCLUSION While these morphs sometimes differ in their maintenance energy expenditures, the differences in MMR profile in this study are not consistent with maintenance of the polymorphism via a simple correlated response to selection across multiple niches. When present, differences in MMR profile do not indicate the existence of multiple thermal niches that consistently mirror colour polymorphism. We suggest that while a relationship between colour morph and thermal niche selection appears to exist it is neither simple nor consistent.

中文翻译：

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热生态位选择在维持赤背sal（Plethodon cinereus）颜色多态性中的作用。

背景技术在北美东部，大多数赤背sal（Plethodon cinereus）种群中存在两种常见的颜色形态。先前的研究表明，不同的形态可能适应于不同的热生态位，并且形态变异已与一个灰葡萄种群在15摄氏度下的标准代谢率有关。因此，已经假设对跨热位的代谢率的选择的相关响应维持了灰黄假单胞菌的颜色多态性。这项研究检验了该假设。结果我们发现，这两种颜色的形态有时在维持代谢率（MMR）分布方面确实有所不同，但是在人群或季节之间，这种图案并不一致。我们还发现，当MMR配置文件之间的形态不同时，这些差异并不表示存在不同的壁ni。现场普查显示，有时在不同的底物温度下会发现两种颜色，并且这种差异还取决于普查的位置和季节。结论虽然这些形态有时在维持能量上有所不同，但本研究中MMR谱的差异与通过对多个生态位的选择的简单相关反应来维持多态性并不一致。如果存在，则MMR配置文件中的差异并不表示存在多个始终反映颜色多态性的热环境。我们建议，虽然颜色变体和热生态位选择之间似乎存在关系，但它既不简单也不一致。现场普查显示，有时在不同的底物温度下会发现两种颜色，并且这种差异还取决于普查的位置和季节。结论虽然这些形态有时在维持能量上有所不同，但本研究中MMR谱的差异与通过对多个生态位的选择的简单相关反应来维持多态性并不一致。如果存在，则MMR配置文件中的差异并不表示存在多个始终反映颜色多态性的热环境。我们建议，虽然颜色变体和热生态位选择之间似乎存在关系，但它既不简单也不一致。现场普查显示，有时在不同的底物温度下会发现两种颜色，并且这种差异还取决于普查的位置和季节。结论虽然这些形态有时在维持能量上有所不同，但本研究中MMR谱的差异与通过对多个生态位的选择的简单相关反应来维持多态性并不一致。如果存在，则MMR配置文件中的差异并不表示存在多个始终反映颜色多态性的热环境。我们建议，虽然颜色变体和热生态位选择之间似乎存在关系，但它既不简单也不一致。