engleski

Is it Possible to Detect Narrow-clawed and Noble Crayfish Probable Hybrids Using Multivariate Discriminant Analysis of Morphometric Data?

Hybrids between narrow-clawed crayfish (Astacus leptodactylus) and noble crayfish (Astacus astacus) have been obtained under laboratory conditions and their occurrence within natural habitats has been sporadically mentioned, but no detailed study has been conducted so far to confirm or deny their existence in the wild. In Croatia, both A. astacus and A. leptodactylus are native, with the latter expanding west- and southwards and displacing A. astacus. During a distribution survey on the Mrežnica River, both species were recorded ; with A. astacus distributed upstream, A. leptodactylus downstream, and specimens of questionable species affiliation based on morphology, possibly representing potential hybrids, being found in-between the two. Therefore, the aim of this research was to verify if the specimens of peculiar morphology, found in the middle part of the Mrežnica River, are hybrids. To test this possibility, the morphometric characteristics from specimens caught from all three parts of the Mrežnica River were studied and analysed using multivariate discriminant analysis (MDA). Extra A. astacus and A. leptodactylus specimens from populations whose determinations are indisputable according to morphological characteristics, were also included in the analyses. The results showed a clear separation between A. astacus and A. leptodactylus. Specimens of peculiar morphological appearance and, unexpectedly, ones from what was thought to be A. astacus were positioned in-between the two, which indicates the possibility that the middle and upper parts of the Mrežnica River are inhabited by probable hybrids. Ongoing molecular analyses of collected samples will help to resolve these morphometric results.

Astacus astacus ; Astacus leptodactylus ; discriminat analysis ; natural populations

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