The influence of altitude on the size and shape of two newt species Triturus cristatus (Laurenti, 1768) and Triturus dobrogicus (Kiritzescu, 1903) in Slovakia
Abstract
We analyze the relationships between the altitude as an ecological factor and the length of limbs in two closely related species of newts, Triturus cristatus and Triturus dobrogicus. We mainly focused on changes in the length of limbs that are important variables in classification using Wolterstorff index. Finding that the values of Wolterstorff index in individuals at extreme altitudes frequently overlap, put forward the idea of underlying dependence in their morphological characters. We found that in T. dobrogicus body size of males and females is inversely related to altitude, i.e. the individuals from sites in higher altitudes are smaller. There was no significant difference between sexes in this case. In T. cristatus body size increases with altitude, but only in males, not in females. There were no significant differences in body size between sexes of this species. Both species show significant sexual dimorphism in body shape measured by the length of both their limbs and trunks. Males have longer limbs and shorter trunks than conspecific females. Females of T. dobrogicus exhibit shorter and narrower heads than males. There were no significant differences related to altitude in T. dobrogicus. Females of T. cristatus have longer limbs and shorter trunks at higher altitudes, but this trend was not found in conspecific males. Though there is a trend in change of female body shape in T. cristatus, neither T. cristatus nor T. dobrogicus were significantly different in body shape. Principal Component Analysis revealed also correlation between limb length and interlimb distance. In spite of apparent trend in the change of the limb length in relation to the altitude this correlation was not significant. However, comparing more morphological (head morphology) and environmental variables and analyzing larger samples in the future may bring new knowledge on ecology, relationships and evolution of these two species.
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