Zoological Studies

Vol. 55, 2016

(update: 2016.3.31)

Morphological differentiation of the skull in two closely-related mustelid species (Carnivora: Mustelidae)

Alexei V. Abramov1,*, Andrey Yu. Puzachenko2, and Igor L. Tumanov3

1Zoological Institute, Russian Academy of Sciences, Universitetskaya nab. 1, Saint Petersburg 199034, Russia
2Institute of Geography, Russian Academy of Sciences, Staromonetnyi per. 29, Moscow 119017, Russia. E-mail: andreypuzak@gmail.com
3B.M. Zhitkov All-Russian Research Institute of Game Management and Fur Farming Animal Breeding, North-Western Branch, Saint Petersburg 199004, Russia. E-mail: itumanov@rambler.ru

A morphological differentiation (i.e., the amount of morphological space occupied) in two polecat species, Mustela putorius and M. eversmanii, has been studied. These closely related species are similar in the body size, the age of origin, and many aspects of their natural history. We have used cranial characters to estimate some parameters of morphological diversity, to compare ‘morphological niche breadth’ occupied by polecats in the morphological space and their overlap, assuming that variation in the characteristics of morphological diversity could be reflected in the extent of adaptive diversification. A comparison of diversity based on 23 cranial characters shows that the polecats occupied distinct areas of the morphospace. Both skull ‘size’ and ‘shape’ characters are important components of the morphological differentiation between M. putorius and M. eversmanii. It seems that the difference between these polecat species is accounted for the ecological pattern rather than the phylogenetic one. Resource partitioning and the lessening of their ecological niches’ overlap in two sympatric carnivores could apparently explain the observed differences of their morphospaces. The morphological diversity of the European polecat is higher than that of the steppe polecat. A possible explanation of this phenomenon is likely to lie in the differences between prey ranges of these species. The morphological diversification in M. putorius could be facilitated by its adaptations to forest habitats of the temperate zone with a wide range of potential prey, whereas M. eversmanii could have evolved under more severe conditions of arid Eurasian habitats with a possible prey specialization.

Key words: Cranial variation, Mustela putorius, Mustela eversmanii, Morphospace, Polecats.

*Correspondence: E-mail: a.abramov@mail.ru

Vol. 55, 2016