title: Thermoregulation and microhabitat choice in the polymorphic asp viper (Vipera aspis).
abstract: In ectotherms, thermoregulation strongly depends on environmental conditions, as well as on intrinsic factors, such as skin colour. Indeed, due to its physical properties, melanin pigments allow melanistic morphs to benefit of a more efficient thermoregulation compared to non-melanistic ones. Despite thermal benefits of melanism have often been highlighted under experimental conditions, such field data remain scarce. In this study, we investigated the influence of colouration on body temperature and microhabitat choice in a montane population of colour polymorphic asp viper (Vipera aspis) characterized by a strong presence of melanism (64%). Results highlighted a difference in internal body temperature, but only within gravid females, with melanistic individuals having higher body temperatures compared to non-melanistic ones. No differences were found when considering both sexes. We also showed that melanistic and non-melanistic vipers were found in different microhabitat types, i.e. melanistic snakes used areas marked by a scarcer sun exposure and by higher vegetation cover compared to non-melanistic ones. This result has important implications. Indeed, besides providing a possible explanation for the lack of difference in body temperature (except for gravid females), it confirms that melanistic individuals can potentially use their efficient thermoregulation in order to inhabit less exposed and thermally unfavourable microhabitats.
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Daniele
authors.initials: D
authors.lastname: Muri
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Johan
authors.initials: J
authors.lastname: Schuerch
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Naïke
authors.initials: N
authors.lastname: Trim
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Golay
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Baillifard
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland.
authors.forename: Athimed
authors.initials: A
authors.lastname: El Taher
authors.affiliation: Department of Ecology and Evolution, University of Lausanne, 1015 Lausanne, Switzerland. Electronic address: sylvain.dubey@unil.ch.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Dubey
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001831:Body Temperature; D017753:Ecosystem; D005260:Female; D008297:Male; D008543:Melanins / Q000378:metabolism; D012880:Skin Pigmentation; D017819:Viperidae / Q000378:metabolism / Q000502:physiology*
chemical_list: D008543:Melanins
keywords: Melanism; Microhabitat; Reptiles; Thermal benefits; Thermoregulation