Comparison of ventral spotting in Bombina variegata between northern Slovakian localities

Abstract

A comparison of ventral spotting of the yellow-bellied toad (Bombina variegata) was investigated in four localities (Kysucká vrchovina, Spišská Magura, Spišsko-šarišské medzihorie and Bukovské vrchy). The research complements previous results from 2014 and 2022 with the addition of new samples from 2022 and 2023. The resulting patterns were evaluated by principal component analysis (PCA) and differences between territories were examined. The most signifcant factors were related to spotting or morphology of individuals. The frst component (PC1) is related to melanism, to which the variables characterising spotting contribute signifcantly. Individuals from the Spišsko-Sarišské medzihorie region had the darkest overall colour (most patches, high proportion of B/Y, etc.). The second signifcant component (PC2) is related to the size of individuals. Size differentiation of B. variegata (PC2) showed signifcant differences between individuals from different areas. Individuals from Spišská Magura were larger than individuals from other regions. PC3 defnes the size of spots; our fndings revealed signifcant regional differences. The largest spots were observed in the Spiš-Šariš population. We did not evaluate PC4 further due to image processing errors which were considered to be methodological error. PC5 represents the number of dark patches. Individuals from Spišská Magura showed a higher number of dark patches than other populations. PC6 is related to variation in hind leg length. This means that it is also related to the size of individuals. Similarly, individuals from Spišská Magura were larger. As abdominal spotting is an aposematic colouration, playing a role in deterring predators but also in camouflage and sexual selection, these variations may represent local adaptations of the species. Individual size may correspond to differences in habitat quality, resource availability or other ecological factors affecting growth.