Aposematism and crypsis are not enough to explain dorsal polymorphism in the Iberian adder

Martínez‐Freiría, Fernando; Lanuza, Guillem Pérez i de; Pimenta, António A.; Pinto, Tiago; Santos, Xavier

doi:10.1016/j.actao.2017.11.003

Cited by 17 publications

(24 citation statements)

References 30 publications

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“…In snakes, intraspecific studies have indicated that melanistic individuals can exhibit increased growth rates, better body conditions and locomotor performances, longer activity periods, or higher female fertilities than non-melanistic ones [9][10][11][12] . Conversely, melanism or lack of dorsal pattern could increase detectability and thus, make dark snakes more vulnerable to predators [13][14][15][16] . This trade-off between predation and thermoregulation is likely behind the inability of the aforementioned studies to establish links between the occurrence of melanism and climatic factors, and therefore, to confirm the predictions of the thermal melanism hypothesis in snakes.…”

Section: Thermal Melanism Explains Macroevolutionary Variation Of Dormentioning

confidence: 99%

“…The relationship between colour phenotypes and predation has been recurrently explored in viperid snakes (Serpentes, Viperidae). Vipers frequently exhibit a zigzag dorsal pattern 17 that endorses both aposematic and cryptic functions [15][16][17][18][19] . Melanistic vipers, however, do not exhibit the zigzag pattern.…”

Section: Thermal Melanism Explains Macroevolutionary Variation Of Dormentioning

confidence: 99%

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Thermal melanism explains macroevolutionary variation of dorsal pigmentation in Eurasian vipers

Martínez‐Freiría

Toyama

Freitas

et al. 2020

Sci Rep

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Colouration may endorse thermoregulatory and antipredatory functions in snakes. The thermal melanism hypothesis predicts that dark-coloured individuals are ecologically favoured in cool climates. However, the loss of aposematic and cryptic colourations may imply high predation for melanistic snakes. Here, we used the monophyletic group of Eurasian vipers (subfamily Viperinae) to test whether an increase in the extent of dark area inside the characteristic zigzag dorsal pattern is associated to colder environments. We measured two colouration traits in zigzag-patterned individuals (number of dorsal marks and weighted pigmentation index) and used a phylogenetic comparative approach to explore macroevolutionary patterns of dorsal pigmentation and test whether its extent is associated to ecogeographic characteristics of lineages’ ranges. Phylogenetically-naïve and phylogenetically-informed analyses yielded a significant association between the degree of pigmentation of the zigzag pattern and environmental variables such as solar radiation, elevation and latitude. The degree of pigmentation of the zigzag pattern is highlighted as an adaptive trait that matches range attributes mirroring cold environments irrespective of the phylogeny. These results constitute the first large-scale evidence supporting the thermal melanism hypothesis in snakes, opening new avenues of inquiry for the mechanisms that shape the evolution of colour phenotypes.

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Section: Thermal Melanism Explains Macroevolutionary Variation Of Dormentioning

confidence: 99%

Section: Thermal Melanism Explains Macroevolutionary Variation Of Dormentioning

confidence: 99%

Thermal melanism explains macroevolutionary variation of dorsal pigmentation in Eurasian vipers

Martínez‐Freiría

Toyama

Freitas

et al. 2020

Sci Rep

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“…Zuffi et al, 2009). Furthermore, distinct predation pressures at lowland and montane habitats (see Martínez-Freiría et al, 2017) might differentially affect survival, driving biometric differences among individuals from these environments. The patterns of variation observed for linear biometric traits of the four colour morphs of V. seoanei examined here may be partially explained according to this hypothesis.…”

Section: Discussionmentioning

confidence: 99%

“…Age groups, however, were not further considered, as size-related variation was represented through body size (SVL) for subsequent analyses. Additionally, we classified each specimen in one of five colour morphs (bilineata, classic, cantabrica, melanistic and uniform) following criteria used in previous works (Martínez-Freiría and Brito, 2013; Martínez-Freiría et al, 2017). The uniform type was very rare in our dataset (n = 6; Supp.…”

Section: Methodsmentioning

confidence: 99%

“…It is distributed across north-western Portugal and northern Spain, with some populations penetrating a few kilometres into south-western France (Braña, 2002; Brito, 2008; Martínez-Freiría and Brito, 2014). Vipera seoanei exhibits low intraspecific phylogenetic variability and is characterized by high levels of polymorphism in pholidotic traits and colour morphs (Bea et al, 1984; Saint-Girons, Braña and Bea, 1986; Martínez-Freiría and Brito, 2013; Martínez-Freiría, Velo-Antón and Brito, 2015, Martínez-Freiría et al, 2017). Pholidotic trait variability correlates to variation in climatic conditions across the species’ range and, thus, these traits were suggested to be under selection or to be shaped by plasticity (Martínez-Freiría and Brito, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Sources of Intraspecific Morphological Variation inVipera seoanei: Allometry, Sex, and Colour Phenotype

Lucchini

Kaliontzopoulou

Val

et al. 2020

Preprint

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13Snakes frequently exhibit ontogenetic and sexual variation in head dimensions, as well as 14 the occurrence of distinct colour morphotypes which might be fitness-related. In this 15 study, we used linear biometry and geometric morphometrics to investigate intraspecific 16 morphological variation related to allometry and sexual dimorphism in Vipera seoanei, a 17 species that exhibits five colour morphotypes, potentially subjected to distinct ecological 18 pressures. We measured body size (SVL), tail length and head dimensions in 391 19 specimens, and examined variation in biometric traits with respect to allometry, sex and 20 colour morph. In addition, we analysed head shape variation by recording the position of 21 29 landmarks in 123 specimens and establishing a low-error protocol for implementing 22 geometric morphometrics to European vipers. All head dimensions exhibited significant 23 allometry, while sexual differences occurred for SVL, relative tail length and snout 24 height. After considering size effects, we found significant differences in body 25 proportions between the sexes and across colour morphs, which suggests an important 26 influence of lowland and montane habitats in shaping morphological variation. By 27 contrast, head shape did not exhibit significant variation across sexes or colour morphs. 28Instead it was mainly associated to allometric variation, where the supraocular and the 29 rear regions of the head were the areas that varied the most throughout growth and across 30 individuals. Overall, this study provides a thorough description of morphological 31 variability in Vipera seoanei and highlights the relevance of combining different tools 32 (i.e. linear and geometric morphometrics) and analyses to evaluate the relative 33 contribution of different factors in shaping intraspecific variation.34 35 36 37 38 Understanding how morphological variation across individuals arises and how it is 39 distributed both temporally and spatially have attracted the attention of biologists over 40 the years (Verwaijen, Van Damme and Herrel, 2002; Harmon et al., 2003; 41 Kaliontzopoulou, Pinho and Martínez-Freiría, 2018). 42 Size is the predominant axis of morphological variation within and among populations 43 (Rohlf, 1990). As such, allometry, the dependence of shape on size, is a major framework 44 for understanding how and why different traits vary (Klingenberg, 2016). First, changes 45 in size and shape occurring during growth and their relationship (i.e. ontogenetic 46 allometry) are of essential importance for investigating the developmental processes 47 producing the structures of interest (McNamara, 2012). Second, allometric variation 48 across individuals at the same developmental stage within a population (i.e. static 49 allometry) can be informative on the selective processes acting on individuals, since 50 allometric parameters can be directly linked to both ecological adaptation (Gould, 1966) 51and sexual selection (Bonduriansky and Day, 2003). Indeed, body structures that are of 52 partic...

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Bad moon rising? The influence of the lunar cycle on amphibian roadkills

et al. 2019

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Aposematism and crypsis are not enough to explain dorsal polymorphism in the Iberian adder

Cited by 17 publications

References 30 publications

Thermal melanism explains macroevolutionary variation of dorsal pigmentation in Eurasian vipers

Thermal melanism explains macroevolutionary variation of dorsal pigmentation in Eurasian vipers

Sources of Intraspecific Morphological Variation inVipera seoanei: Allometry, Sex, and Colour Phenotype

Bad moon rising? The influence of the lunar cycle on amphibian roadkills

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