Ecomorphology and trophic ecology are considered important features in comprehending the feeding structure of fish communities. This study assesses the ecomorphological relationships among 45 fish species inhabiting the Eastern Himalayan torrential rivers, Murti and Jaldhaka by identifying morphological and trophic associations highlighted by prey acquisition strategies and the potential phylogenetic convergence among morphological traits. Two approaches (3-guild and 5-guild) were employed for evaluating the prediction accuracy of morphology in classifying the guilds. While the former was based on “troph” (dietary index) values, the later focussed on diet dissimilarity matrix. In terms of phylogenetic relatedness, traits such as caudal peduncle aspect ratio and mouth protrusion showed prominent phylogenetic signal which suggested their evolutionary convergence in certain groups. Subsequent modelling suggested that while linear discriminant model showed morphological traits to have higher accuracy (91.1%) in classifying the three guilds as compared to five guilds (72.31%), redundancy model (explaining 85.26% constrained variance) revealed a morphological association with specific prey type selection. Additionally, linear models showed substantial variation (93.72%) in the dietary index being addressed by the 5-guild classification as compared to the 3-guild (79.72%). Results suggested that in terms of prey composition or selectivity, the 5-guild model was more suited in representing the feeding structure while the morphological traits reflected a broader scheme of classification (3-guild model). Hence, this provides an ecological insight into the different modes of resource utilisation by the coexisting species which are being expressed in their differentiating morphologies, with certain traits being phylogenetically conserved within specific feeding groups.

中文翻译：

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形态在塑造印度西孟加拉邦东喜马拉雅河流中鱼类觅食生态位中的作用

生态形态学和营养生态学被认为是理解鱼类群落摄食结构的重要特征。本研究通过识别由猎物获取策略突出的形态和营养关联以及形态特征之间的潜在系统发育趋同，评估了栖息在喜马拉雅东部河流、穆尔蒂和贾尔达卡的 45 种鱼类之间的生态形态关系。使用两种方法（3-guild 和 5-guild）来评估形态学在行会分类中的预测精度。而前者是基于“ troph”（饮食指数）值，后者侧重于饮食差异矩阵。在系统发育相关性方面，尾柄纵横比和嘴巴突出等特征显示出显着的系统发育信号，表明它们在某些群体中的进化趋同。随后的建模表明，虽然线性判别模型显示形态特征在对三个公会进行分类时具有更高的准确率（91.1%），但与五个公会（72.31%）相比，冗余模型（解释了 85.26% 的约束方差）揭示了与特定猎物的形态学关联类型选择。此外，线性模型显示，与 3 级 (79.72%) 相比，5-级分类所解决的饮食指数存在显着差异 (93.72%)。结果表明，在猎物组成或选择性方面，五行模型更适合代表饲养结构，而形态特征反映了更广泛的分类方案（三行模型）。因此，这提供了对共存物种的不同资源利用模式的生态洞察，这些物种以其不同的形态表现出来，某些特征在特定的摄食群体中在系统发育上是保守的。