Colour polymorphism; Evolution; Genetics; Melanism; Thermoregulation; Adaptation; Climate change; Fitness; Ectotherm; Reptile; Vipera aspis
(2014), Evolutionary and biomedical consequences of internal melanins, in Pigment Cell & Melanoma Research
, 27, 327-338.
(2014), Multiple origins of invasive and « native » water frogs (Pelophylax spp.) in Switzerland, in Biological Journal of the Linnean Society
, 112, 442-449.
(2014), Role of climate on the presence of colour polymorphism in two montane reptile species, in Biology Letters
, 10, 20140638.
(2014), The genetic identity of the critically endangered Wimmer’s shrew Crocidura wimmeri, in Biological Journal of the Linnean Society
, 111, 224-229.
(2014), The proopiomelanocortin POMC gene and melanin-based colour polymorphism in a snake, in Biological Journal of the Linnean Society
, (111), 160-168.
(2013), Amphibians in the diet of European Barn Owls, in Bird study
, (60), 264-269.
(2013), Assessment of terrestrial small mammals with records of the critically endangered shrew Crocidura wimmeri in the Banco National Park (Côte d’Ivoire), in Mammalia
, 4, 439-446.
(2013), Colour polymorphism and body condition in the Asp viper, in Journal of Zoology
, 290, 273-280.
(2013), Effects of season, sex and body size on the feeding ecology of turtle-headed seasnakes (Emydocephalus annulatus) on IndoPacific inshore coral reefs, in Coral Reefs
, 32, 527-538.
(2013), Homologous sex chromosomes in three deeply divergent anuran species, in Evolution
, 67, 2434-2440.
(2013), Multiple Paternity in Polyandrous Barn Owls (Tyto alba), in PLoS ONE
, 8, e80112-e80112.
(2013), New record of Crocidura zarudnyi from Zabol, Iran, in Zoology and Ecology
, 23, 162-164.
(2013), Population demography of an endangered lizard, the Blue Mountains Water Skink (Eulamprus leuraensis), in BMC Ecology
, 13, 4-4.
(2012), Phylogeography and dispersal in the velvet gecko (Oedura lesueurii), and potential implications for conservation of an endangered snake (Hoplocephalus bungaroides), in BMC Evolutionary Biology
, 12, 67-86.
(2012), Are reptile and amphibian species younger in the Northern Hemisphere than the Southern Hemisphere?, in Journal of Evolutionary Biology
, 25, 220-226.
(2012), Colour-polymorphic snake species are older, in Biological Journal of the Linnean Society
, 107(1), 210-218.
(2012), Disparity in the timing of vertebrate diversification events between the Northern and Southern Hemispheres, in BMC Evolutionary Biology
, 12, 244.
(2012), Host-parasite relationships during a biologic invasion: 75 years postinvasion, cane toads and sympatric Australian frogs retain separate lungworm faunas., in Journal of Wildlife Diseases
, 48(4), 951-961.
(2012), Multiple refugia and barriers explain the phylogeography of the Valais shrew, Sorex antinorii, in Biological Journal of the Linnean Society
, 105, 864-880.
(2012), The occurrence of reptiles in European Barn Owl diet, in Bird Study
, (iFirst), 1-5.
, Evolutionary and biomedical consequences of internal melanins, in Pigment Cell & Melanoma Research
, Interpopulation differences in parental care expression, in Journal of Animal Ecology
, Introduced freshwater blenny influences the diet and body condition of the invasive dice snake in Lake Geneva, in Journal of Wildlife Management
, Invader immunology: invasion history alters immune-system function in cane toads (Rhinella marina) in tropical Australia, in Ecology Letters
, Predicting the impacts of climate change on genetic diversity in an endangered lizard species, in Climatic Change
Many factors contribute to a population’s ability to persist in the face of climatic variation. Previous research has emphasised the possible roles of factors such as life-history traits, physiological tolerance to cold, and energy requirements in this respect. My project will focus on another potential contributor to population resilience: the presence of colour polymorphism. An ectotherm’s body colour affects many facets of its existence, including fitness-relevant functions such as thermoregulation, foraging behaviour, metabolic physiology, and prey-predator interactions. Colour polymorphism within a population may thereby expand the range of environmental conditions under which at least some individuals are well-suited to meeting local challenges, even when those challenges vary considerably over small spatial and temporal scales. Body colour is likely to be especially significant for ectothermic animals, because of their reliance upon ambient conditions for thermoregulation. In particular, the relationship between an organism’s colour and the local environment is critical for ambush-foraging ectotherms, that rely upon background colour-matching to evade detection by potential prey. Thus, colour traits in such species will be subject to complex multifunctional optimisation. The ideal model system in which to explore the ecological consequences of colour polymorphism would be a lineage of ectothermic ambush-foragers, widely distributed over Europe (in present days as well as during historical climatic fluctuations), and exhibiting discrete colour polymorphism. The genus Vipera fulfils these criteria: (i) It comprises 21 species of medium-sized viviparous snakes distributed in the Palaearctic, and genetic data suggest that these snakes persisted in European refugia more successfully than did most other taxa of reptiles and amphibians; (ii) many viperid taxa exhibit extensive intraspecific color variation: for example, in addition to the “normal” (brown-blotched) form, taxa such as V. aspis, V. berus, and V. seoanei exhibit both melanic morphs and uniformly light-coloured morphs. In fact, the asp viper (V. aspis) is one of the most chromatically variable snakes in the world. Its abundance and wide distribution have made this species one of the most intensively studied reptiles in the Northern Hemisphere. It is present over a wide elevational gradient through its range (as in Switzerland) with dorsal colouration varying among as well as within populations. For example, up to 50% of individuals at high elevation are melanistic, probably as an adaptation to enhance rates of heat transfer during basking, whereas “normal” or uniformly light (concolor) morphs dominate in other populations. The frequency of alternative colour morphs also depends on parameters such as body size and sex; for example, melanic morphs are more common in adult females than in adult males. This system thus is ideally suited to provide a robust understanding of how body colour affects organismal fitness in a population of ectotherms, and how chromatic polymorphism might modify the impact of climate change on population viability. My study centres on the hypothesis that colour polymorphism within vipers allows these taxa to exploit a broader range of environmental conditions, hence increasing their ability to persist despite the challenges imposed by environmental changes such as global warming. I will test this hypothesis using molecular genetic analyses to reveal the phylogenetic history of colour polymorphism within the Vipera clade and to identify genetic determinants of the relevant colour traits. In addition, I will manipulate thermal regimes of captive vipers (to explore behavioural responses to environmental conditions for various colour morphs) and conduct field studies to investigate ecological correlates of colour in free-ranging snakes from several sites. More specifically, my research will: (a) identify the gene(s) responsible for the melanin-based colour polymorphism in three viper species (V. aspis, V. berus, V. seoanei) by sequencing candidate genes (e.g. MC1R, TYRP1) and by comparative analysis of full transcriptomes via next-generation sequencing technology (454/Roche, Solexa) in melanic, concolor, and “normal” individuals from multiple populations, (b) determine the number of independent origins of colour polymorphism within this lineage, by performing phylogenetic analyses of the gene(s) identified in point a) (multiple independent evolutionary origins of polymorphism would strongly support the hypothesis that colour polymorphism offers a significant selective advantage), (c) quantify the fitness consequences of the interaction between thermal conditions and snake colour, by manipulating basking opportunities for gravid V. aspis and their offspring in the laboratory (i.e., identify morph-specific thermal optima for ecological traits such as feeding rate, body conditions, fecundity, and growth rate), and (d) evaluate how a snake’s body colour influences fitness-relevant traits in the field and/or in the laboratory, by quantifying aspects of behaviour: antipredator responses, thermoregulatory tactics, heating and cooling rates, habitat selection (especially, background colour-matching in selection of ambush sites), organismal performance (sprint speed, endurance, strike speed and accuracy) of snakes of different colour morphs. My study will clarify the ecological significance of colour variation in a wide-ranging ectotherm species, and provide a direct empirical test of the hypothesis that a population containing individuals of a wide range of dorsal colours is able to exploit a broader range of environmental conditions than could a monomorphic population - and hence, that the evolution of colour polymorphism may have had significant lineage-wide consequences for the ability of viperid snakes to withstand past climatic extremes (e.g. Pleistocene glaciations) more successfully than did other (monomorphic) taxa. Clearly, understanding how species have dealt with climate change in the past can provide valuable insights into how they are likely to respond in the future, and will shed light on the likely impacts of global warming.