Modern taxonomy relies on the unified species concept and integrative approaches to delimit evolutionary coherent taxa. The western Mediterranean vipers within the Vipera latastei-monticola complex (Vipera latastei and Vipera monticola) have a rather old taxonomic history marked by the prevalence of morphological criteria in the recognition of taxonomic units. Recent phylogenetic inferences, however, contradict this taxonomic scenario, highlighting the need of integrative studies to properly evaluate the taxonomy of this complex. Here, we apply an integrative taxonomic approach, combining phylogeographic, morphological, and ecological analyses, to identify and describe evolutionary coherent taxonomic units within the Vipera latastei-monticola complex. Using dated mtDNA phylogenetic relationships, we spatially delimit two levels of evolutionary units, which are the subject of morphological and ecological comparisons. The first level corresponds to two Miocene vicariant clades, with considerable morphological distinctiveness that we identified as different species:V. latastei in the Iberian Peninsula, and V. monticola in North Africa. The second level corresponds to three Pliocene parapatric lineages within each of these species, which we recognized with subspecific status due to non-apparent geographic isolation and variable levels of phenotypic distinctiveness. Consequently, we propose distributional rearrangements in the previously recognized taxa, as well as define three new subspecies: Vipera latastei arundana ssp. nov. in southern Iberia, Vipera monticola atlantica ssp. nov. in the western High Atlas Mountains and Vipera monticola saintgironsi ssp. nov. in the eastern High Atlas, Middle Atlas, Rif, Tellian Atlas and Aurès Mountains.Our proposed taxonomic scenario anticipates important outcomes for the conservation status of these Mediterranean taxa.

Snakes frequently exhibit ontogenetic and sexual variation in head dimensions, as well as the occurrence of distinct colour morphotypes which might be fitness-related. In this study, we used linear biometry and geometric morphometrics to investigate intraspecific morphological variation related to allometry and sexual dimorphism in Vipera seoanei, a species that exhibits five colour morphotypes, potentially subjected to distinct ecological pressures. We measured body size (SVL), tail length and head dimensions in 391 specimens, and examined variation in biometric traits with respect to allometry, sex and colour morph. In addition, we analysed head shape variation by recording the position of 29 landmarks in 123 specimens and establishing a low-error protocol for implementing geometric morphometrics to European vipers. All head dimensions exhibited significant allometry, while sexual differences occurred for SVL, relative tail length and snout height. After considering size effects, we found significant differences in body proportions between the sexes and across colour morphs, which suggests an important influence of lowland and montane habitats in shaping morphological variation. By contrast, head shape did not exhibit significant variation across sexes or colour morphs. Instead it was mainly associated to allometric variation, where the supraocular and the rear regions of the head were the areas that varied the most throughout growth and across individuals. Overall, this study provides a thorough description of morphological variability in Vipera seoanei and highlights the relevance of combining different tools (i.e. linear and geometric morphometrics) and analyses to evaluate the relative contribution of different factors in shaping intraspecific variation.

AimAllopatric speciation is the primary mode of diversification in the Mediterranean Basin. However, the contribution of climatic adaptation during this process is contradictory. In this work, we investigate the eco‐evolutionary processes that drove diversification in this region, using European vipers as a case study. We describe the climatic requirements of different lineages to compare their responses to the Pleistocene climatic oscillations and tackle the evolutionary mechanisms underlying their diversification.LocationEurasia and North Africa.TaxonEuropean vipers (genus Vipera).MethodsWe used ecological niche modelling (ENM) to identify the climatic requirements of 24 Vipera lineages and infer past range dynamics associated with their diversification during the Pleistocene. To test whether climatic niches varied across lineages, we calculated the phylogenetic signal of different climatic variables and examined the relationship with phylogenetic relatedness. To investigate climatic niche evolution and test for phylogenetic niche conservatism (PNC), we quantified pairwise niche overlap in sister phylogenetic units under a 3D hypervolume approach.ResultsENM identified temperature annual range, precipitation of wettest month and precipitation of driest quarter as the most important climatic variables related to the distribution of most lineages, validating Pelias clade as cold‐adapted, and Vipera 1 and Vipera 2 as warm‐adapted clades. Projections to past conditions varied among clades, with Pelias and Vipera 1 having more similar responses, while Vipera 2 exhibited greater variability. We found significant phylogenetic signal in one temperature‐related and two humidity‐related climatic variables and detected high complexity in ecological niche evolution across the phylogeny, both rejecting the hypothesis of PNC.Main ConclusionsClimatic adaptation played a significant role in driving diversification among European vipers. Cold‐adapted and warm‐adapted lineages presented similar climatic requirements and remarkable responses to Pleistocene stages, resulting in an intricate pattern of niche divergence along the phylogeny that favours local adaptation rather than PNC.

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...