Melanism, body condition and elevational distribution in the asp viper

Abstract

Alternative morphotypes can confer important selective advantages in different habitats, whereas they can be penalized in other circumstances. In ectotherms, such as reptiles, the body colour can have direct effects on numerous aspects of their existence, such as thermoregulation or prey–predator interactions. Darker melanic individuals show lower skin reflectance and consequently heat up more rapidly and maintain optimal body temperatures more easily than lighter coloured individuals. As a consequence, melanistic individuals of diurnal species in cool areas may exhibit higher body condition, growth rate, survival and fecundity than lighter coloured individuals. Such advantages of dark coloration may be counterbalanced by a lower crypsis to predators and a decreased foraging efficiency. We investigated, in two montane populations of asp vipers Vipera aspis, the relationship between (1) colour polymorphism and body condition and length and (2) the coloration of individuals and their elevational distribution. We showed significant relationships between (1) the coloration, body condition and sex of individuals; (2) sexes and reproductive state and morph frequency; and (3) colour morphs that were distributed following an elevational gradient. Hence, colour polymorphism plays an important role in the ecology and evolution of the asp viper and is maintained through differential selective pressures.

Effect of body mass and melanism on heat balance inLiolaemuslizards of thegoetschiclade

“…Therefore, individuals inhabiting cold climates are expected to benefit from having melanic coloration, and effective thermoregulation should result in greater fitness (Clusella-Trullas et al, 2007). However, these statements are mainly supported in arthropods (Pereboom and Biesmeijer, 2003), whereas the studies conducted in ectothermic vertebrates provided conflictive results (supporting TMH: Gibson and Falls, 1979;Bittner et al, 2002;Clusella-Trullas et al, 2009;Castella et al, 2013;contrary to TMH: Forsman, 1995;Tanaka, 2007Tanaka, , 2009. Our results are somewhat mixed too, although the increasing effect of dorsal melanism on heating rates of living animals supports the TMH.…”

“…Thus, the role of melanism is more complex than expected, or at least not exclusively related to thermal biology (Tanaka, 2009). The complex nature of melanism has been observed previously in ectotherms (Tanaka, 2007(Tanaka, , 2009Janse van Rensburg et al, 2009;Harris et al, 2012;Castella et al, 2013;Roff and Fairbairn, 2013) and some studies have considered melanism to be non-adaptive (e.g. Strugariu and Zamfirescu, 2011).…”

“…Kettlewell, 1973;Kingsolver and Wiernasz, 1991;Clusella-Trullas et al, 2007;Reguera et al, 2014); however, it also is associated with UV radiation protection (Gunn, 1998;Callaghan et al, 2004;Calbó et al, 2005;Reguera et al, 2014), crypsis (Kettlewell, 1973;Endler, 1984;Reguera et al, 2014) and intra-specific communication or sexual selection (Wiernasz, 1989;Fedorka et al, 2013). Additionally, the advantages of melanism may be associated with local conditions (local adaptation; Castella et al, 2013), as a result of phenotypic plasticity (Alho et al, 2010) or the interaction between predator avoidance and thermoregulation (Lindstedt et al, 2009). Thus, the role of melanism is more complex than expected, or at least not exclusively related to thermal biology (Tanaka, 2009).…”

Influence of climate on the presence of colour polymorphism in two montane reptile species

“…The thermal melanism hypothesis has been confirmed in ectothermic vertebrates at small scales (population level), but only for two reptile species, i.e. in the colour-polymorphic adder (Vipera berus) [3,7] and asp viper (Vipera aspis) [6], and at a large scale (species-distribution level) for heliothermic lizards [8]. The latter study found a positive relationship between the skin reflectance of 66 species and the sum of the annual solar radiation present at the sampled sites.…”

Effects of testosterone on the spatial ecology, coloration, and brain regions in western fence lizards, Sceloporus occidentalis

“…In other animals, coloration is positively related to body condition, which in turn is related to an increase in overall fitness (Trigo and Mota, 2014;Castella et al, 2013;Gawryszewski et al, 2012;Cuervo et al, 2009;López et al, 2004;Barber et al, 2000). Body condition relates to fitness through not only natural selection, but also sexual selection, as female lizards appear to prefer males with higher body conditions.…”