Morphological characteristics of non-indigenous brown bullhead Ameiurus nebulosus (Le Sueur, 1819) in lakes of the Karelian Isthmus (Nortwest Europe)
A. O. Yurtseva, M. Yu. Zhukov
Zoological Institute of the Russian Academy of Sciences, Saint Petersburg, Russia
Keywords: non-indigenous species, variability, phenotypic plasticity, morphometric characters, invasive potential
Abstract
Non-indigenous brown bullhead from two lakes of the Karelian Isthmus was studied in relation to 36 morphological features characterizing the shape of the body and head, the position of the fins, the number of finrays and vertebrae. The obtained results were compared with data for the collection materials and earlier published data for other parts of the species distribution range in order to assess the intraspecific differentiation and morphological plasticity of this invasive species. Meristic characters of individuals from geographically distant sites were quite similar and no difference between areas was found. On the contrary, significant differences in morphometric characters between samples from geographically remote water areas of Europe were shown, reaching the thresholds established for subspecies identification. The high level of morphometric variability in the invasive brown bullhead indicates a high phenotypic plasticity in external morphological traits responsible for fish locomotion, which is considered among factors contributing to its successful adaptation to new habitats and determining the invasive potential of this species.
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