The True Colours of Golden Loaches (Teleostei: Cobitidae)

Loaches of the genus Sabanejewia are model organisms for many ichthyologic studies focusing on morphological and colour variation. The bright lateral spots-a part of the mimicry of this fish-cause a taxonomic puzzle. Common practice is that morphometric and molecular studies lack habitat assessments of species originating from different environments. In this study, we analysed body shape and colour variation within two species of Sabanejewia in order to reveal whether they are more affected by phylogeny or environmental conditions. The environmental parameters were obtained using satellite mapping tools, body shape using geometric morphometry, and the molecular identification of specimens using an analysis of mitochondrial DNA (sequence of the cytochrome b gene). Generalized linear mixed models were used for the analysis of lateral spot numbers, and principal components analysis to describe the changes in landmark position defined by the permutation tests. Results show a significant impact of the locality elevation and specimen's sex on the change of the body shape. We identified significant differences in the number of lateral spots, which are considered mimicry variation across an elevation gradient. Morphological differences of Sabanejewia spp. vary with ecological factors along the river continuum.

Automated summary

In this study, we used satellite mapping tools to obtain environmental parameters, geometric morphometry to analyze body shape, and mitochondrial DNA analysis to identify species. Results showed that the change in body shape of Sabanejewia species is significantly influenced by locality elevation and specimen's sex. We also found significant differences in the number of lateral spots, which are considered mimicry variation across an elevation gradient. Morphological differences in Sabanejewia spp. vary with ecological factors along the river continuum.