Resource polymorphism is a ubiquitous phenomenon in vertebrates and may represent a critical intermediate stage in speciation. Freshwater lakes in high‐altitude areas represent a natural system for understanding resource polymorphism in fishes benefiting from diverse lacustrine environments and species‐poor fish assemblages. We report resource polymorphism in a cyprinid fish, Schizopygopsis thermalis , in Lake Amdo Tsonak Co, a headwater lake in the upper Salween River system. Two discrete intraspecific morphs, planktivorous and benthivorous, were identified according to geometric morphometrics and traditional univariate linear measures. The planktivorous morph exhibits a longer head, longer upper and lower jaw, larger asymptotic standard length (L_∞ ), lower growth rate (k ), and higher growth performance index (φ ) than the benthivorous morph. With respect to descriptive traits, the planktivorous morph possesses a large, terminal mouth and obvious mucus pores on the cheek and chin, while the benthivorous morph is characterized by a more inferior mouth with a sharpen horny edge on the lower jaw and unconspicuous mucus pores. The discrete pelagic–benthic resources and low interspecific competition in the lake system might drive the initial differentiation of the two morphs, and partial spatial reproductive isolation in breeding further maintains and reinforces the differences between them.

中文翻译：

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青藏高原萨尔温江水系上游水生热裂殖酵母Herzenstein 1891（双鱼座，鲤科）的上层-底栖资源多态性。

资源多态性是脊椎动物中普遍存在的现象，可能代表物种形成的关键中间阶段。高海拔地区的淡水湖泊是了解鱼类资源多态性的自然系统，这些鱼类得益于不同的湖泊环境和物种贫乏的鱼类种群。我们报告了在安多湖Tsonak Co，上游萨尔温江系统上游水源湖中的一条fish鱼Schizopygopsis Thermalis中的资源多态性。根据几何形态计量学和传统的单变量线性测度，确定了两个离散的种内形态，浮游性和弯食性。所述planktivorous变形表现出更长的头部，再上，下颌骨，较大的渐近标准长度（大号_∞ ），低级增长率（ķ），和更高的生长性能指数（φ比benthivorous变形）。就描述性状而言，浮游性变体在脸颊和下巴上具有较大的末梢嘴和明显的粘液孔，而弯曲食性变体的特征是嘴下端更尖，下颌尖锐的角质边缘和不明显的粘液孔。湖泊系统中分散的上层-底栖资源和较低的种间竞争可能驱动这两种形态的初始分化，并且繁殖中的部分空间生殖隔离进一步保持并加强了它们之间的差异。