No abstract

We used a multidisciplinary approach to infer the taxonomy and historical biogeography of Hierophis viridiflavus and H. gemonensis, performing molecular analyses of itochondrial (16S, Cyt-b, ND4) and nuclear markers (PRLR), a landmark-based morphometric study and a cytogenetic analysis. Our data distinguished three main groups in the studied species, corresponding to H. gemonensis and to two monophyletic clades (E and W) within H. viridiflavus. Clades E and W display a significant genetic (about 4% for Cyt-b and ND4) and morphological divergence and a different morphology of the W sex chromosome (submetacentric in clade E and telocentric in clade W). Taking into account the existing divergence, these clades appear to represent independent phylogenetic units, deserving elevation to species status. Specific names should be H. viridiflavus (Lacepede, 1789) and H. carbonarius (Bonaparte 1833) for cladesWand E, respectively. The phylogeography of the studied species is only partially concordant with a general pattern of ‘southern richness and northern purity’ of genetic diversity, whereas H. gemonensis exhibits high genetic diversity at low latitudes (especially in the Peloponnese), H. carbonarius shows a number of different haplotypes both at low (along the Southern Italian Apennines and in Sicily) and high latitudes in Italy. Furthermore, a relaxed clock model hypothesizes the differentiation between H. gemonensis and H. viridiflavus sensu lato at about 7 Mya, in the Messinian. Subsequently, the speciation involving H. viridiflavus sensu stricto and H. carbonarius took place in the Quaternary, probably as a result of Pleistocene climatic oscillations. Furthermore, our results are consistent with the existence of several ‘refugia within refugia’ in Italy and in the Balkans and depict the major cladogenesis as allopatric events, mainly driven by paleoclimatic and geographical factors

Aim  The aim of this study was to elucidate the phylogeographical pattern of taxa composing the Vipera ursinii complex, for which the taxonomic status and the dating of splitting events have been the subject of much debate. The objectives were to delimit potential refugia and to date splitting events in order to suggest a scenario that explains the diversification of this species complex. Location  Western Europe to Central Asia. Methods  Sequences of the mitochondrial cytochrome b and NADH dehydrogenase subunit 4 (ND4) genes were analysed for 125 individuals from 46 locations throughout the distribution range of the complex. The phylogeographical structure was investigated using Bayesian and maximum likelihood methods. Molecular dating was performed using three calibration points to estimate the timing of diversification. Results  Eighty‐nine haplotypes were observed from the concatenation of the two genes. Phylogenetic inferences supported two main groups, referred to in this study as the ‘ursinii clade’ and the ‘renardi clade’, within which several subclades were identified. Samples from Greece (Vipera ursinii graeca) represented the first split within the V. ursinii complex. In addition, three main periods of diversification were revealed, mainly during the Pleistocene (2.4–2.0 Ma, 1.4 Ma and 1.0–0.6 Ma). Main conclusions  The present distribution of the V. ursinii complex seems to have been shaped by Quaternary climatic fluctuations, and the Balkan, Caucasus and Carpathian regions are identified in this study as probable refugia. Our results support a south–north pattern of colonization, in contrast to the north–south colonization previously proposed for this complex. The biogeographical history of the V. ursinii complex corroborates other biogeographical studies that have revealed an east–west disjunction (situated near the Black Sea) within a species complex distributed throughout the Palaearctic region.

The Hermann's tortoise (Testudo hermanni) is an endangered land tortoise distributed in disjoint populations across Mediterranean Europe. We investigated its genetic variation by typing 1 mitochondrial locus and 9 nuclear microsatellites in approximately 300 individuals from 22 localities. Our goal was to understand the relative impact of natural and human-mediated processes in shaping the genetic structure and to identify the genetic priorities for the conservation of this species. We found that 1) all geographic areas are highly differentiated, mainly as a function of their distance but with a clear genetic discontinuity (F st values larger than 0.4) between the Eastern and the Western subspecies; 2) the contact zone between subspecies is located farthest to the west than previously believed, and it probably coincides with the delta of the largest Italian river; 3) extinction events due to climatic conditions in the Upper Palaeolithic and subsequent human-mediated translocations in the Neolithic possibly explain the unexpected similarity among Spain, Sicily, and Corsica. For conservation purposes, the large majority of genetic pools appears native although hybridization among subspecies, related to extensive 20th century trade of tortoises across Europe, is observed in Spain and some Italian samples. Most populations do not seem at immediate risk of low genetic variation, except the French population, which has very low nuclear genetic diversity (heterozygosity = 0.25) and where 50 out of 51 sampled animals shared the same mitochondrial sequence. In general, restocking and reintroduction plans should carefully consider the genetic background of the individuals.

No abstract

The high frequency of same-sex sexual behaviors (SSB) in free-ranging animals is an evolutionary puzzle because fitness benefits are often unclear in an evolutionary context. Moreover, the physiological and genetic underpinnings of SSB remain unclear. We exploited an extraordinary natural experiment to examine the impact of environmental factors (local sex ratio [SR]) and testosterone (T) levels on SSB in a dense population of Hermann's tortoises monitored for 7 years. Under the combination of high density and extremely skewed SR (~50 females, >1000 males), males courted and mounted other males more frequently than females. They even exhibited extravagant sexual behaviors, attempting to copulate with dead conspecifics, empty shells, and stones. T levels remained within the species' normal range of variation. SSB was not observed in other populations where SR is not, or less skewed, and where density is lower. This study reports the first natural example of a "prison effect," whereby a high population density combined with female deprivation triggered SSB as a mere outlet of sexual stimulation. More generally, it supports the hypothesis that SSB can be a nonadaptive consequence of unusual proximate factors rather than reflecting physiological disorders.

Geostatistics and geographical information system (GIS) procedures are novel techniques helpful for the identification of environmental correlates sustaining contact zones among subspecies or closely related species. In this paper, we tried to infer evolutionary scenarios for Vipera ammodytes across the European part of its distribution area using geostatistics and ecological niche-based models, hence trying to solve several biogeographical questions that remained unclear after the application of classical morphological tools and genetic analyses. Eleven morphological traits from 871 vipers were analysed with geostatistics and ecological niche-based modelling. Interpolation by kriging was used to generate surfaces of morphological variation, which were combined with spatial principal components analysis (SPCA). SPCA maps were used to test putative morphological differentiated groups with discriminant function analysis (DFA). Maximum entropy modelling and seven environmental variables were used to identify factors limiting the distribution of groups and areas for the potential occurrence of such groups. Three patterns of morphological variation were observed: a north-west/south-west cline, transition zones with steep clines of variation in a west-east arc, and particular character traits that disturbed the general cline. SPCA identified between three and nine putative population groups, of which three were supported by DFA. Areas of potential occurrence of these groups were coherent with the range of the three subspecies of V. ammodytes currently recognized. The distribution of all subspecies was mostly related to precipitation in the driest month. Areas of probable sympatry between subspecies are generally small and restricted. The main patterns of geographic variation of morphological characters for V. ammodytes were similar to the patterns obtained for Vipera latastei and Vipera monticola; the same environmental factors limit the distribution of differentiated groups of vipers in the Balkans and the Iberian Peninsula. The influence of humidity on the variation of morphological traits in spatially separated viper taxa from the two European peninsulas coincides with their phylogenetic relatedness. Geostatistics and GIS procedures were successful in the identification of environmental correlates sustaining contact zones among V. ammodytes subspecies in the Balkans. The same techniques should be applied for studying other parapatric forms and refugia regions.

Comparative studies of mortality in the wild are necessary to understand the evolution of aging; yet, ectothermic tetrapods are underrepresented in this comparative landscape, despite their suitability for testing evolutionary hypotheses. We present a study of aging rates and longevity across wild tetrapod ectotherms, using data from 107 populations (77 species) of nonavian reptiles and amphibians. We test hypotheses of how thermoregulatory mode, environmental temperature, protective phenotypes, and pace of life history contribute to demographic aging. Controlling for phylogeny and body size, ectotherms display a higher diversity of aging rates compared with endotherms and include phylogenetically widespread evidence of negligible aging. Protective phenotypes and life-history strategies further explain macroevolutionary patterns of aging. Analyzing ectothermic tetrapods in a comparative context enhances our understanding of the evolution of aging.