Tamagnini, D, Stephenson, J, Brown, RP and Meloro, C (2018) Geometric morphometric analyses of sexual dimorphism and allometry in two sympatric snakes: Natrix helvetica (Natricidae) and Vipera berus (Viperidae). Zoology. ISSN 0944-2006

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Abstract

The non-venomous grass snake (Natrix helvetica) and the venomous adder (Vipera berus) are two native species that are often found in sympatry in Great Britain and Europe. They occupy partially overlapping ecological niches and prey on small vertebrates, but use different feeding strategies. Here, we investigated the morphologies of grass snakes and adders from Dorset (UK) using twodimensional geometric morphometrics to assess the degree of sexual dimorphism in size and shape together with the relative impact of allometry and general body dimensions on head shape. Both species showed significant sexual dimorphism in head size, but not in head shape. We found a clear allometric pattern in N. helvetica, whereas allometry in V. berus was generally less pronounced. Body dimensions were strongly correlated with head shape in the grass snake, but not in the adder. The fact that V. berus is venomous appears to explain the lack of allometric patterns and the lack of an association between body dimensions and head shape. The high degree of size dimorphism identified in both species could originate from the advantages of reduced intraspecific competition that are conveyed by a partial differentiation in feeding morphology.

Item Type:	Article
Uncontrolled Keywords:	0608 Zoology
Subjects:	Q Science > QL Zoology
Divisions:	Natural Sciences & Psychology (closed 31 Aug 19)
Publisher:	Elsevier
Date Deposited:	25 May 2018 08:47
Last Modified:	04 Sep 2021 10:28
DOI or ID number:	10.1016/j.zool.2018.05.008
URI:	https://researchonline.ljmu.ac.uk/id/eprint/8708

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