Geometric Morphometric Analysis of Head Shape in a Spotted Whip Snake (Hemorrhois Ravergieri) in Different Habitats of Iran

Abstract

Morphological patterns of existing variation and investigative concept related to diversity can be very important in understanding the evolution of morphology. It is known that phylogenetic history, size and ecology can all promote the evolution of morphological variation; however, some methods have been recently developed to analyze these aspects for particular body structures. Spotted whip snake Hemorrhois ravergieri appears to have the widest distribution of the Hemorrhois snake genus, especially in Iran. Morphological difference resulting from habitat can occur in several populations of H. ravergieri. Some studies have studied the relation between morphology and habitat use, revealing that motion is the main facilitator of this evolutionary relationship. Now, we consider intraspecific ecomorphological in three habitat types. Geometric morphometric analyses can provide a more detailed image of head shape in three directions (dorsal, lateral and ventral) on three types of habitat: north-west of Iran, north-east of Iran and central Zagros of Iran. Adult specimens were selected and characteristics of head were analyzed, along with body and head size for understanding the proximate mechanisms, which might be involved. The morphological variation between H. ravergieri indicated that variation in size and head dimensions between species and sexes are highly significant in habitat. Males and females differed in head characters and body size; especially, males were found to exhibit a disproportionate increase in head size and dimensions. H. ravergieri from north-east and central Zagros are smaller, than those living in north-west are. The results revealed that considering the previous findings on the populations, the morphological differences were probably not caused by competition between the populations; instead, these traits could be attributed to the natural selection.