Delayed or anticipated reproduction in the asp viper (Vipera aspis)? New field records

Field reports of delayed and anticipated parturition in the viperid snake Vipera aspis

Stable or plastic body shape? Emys orbicularis hatchlings-juveniles growth patterns under different ecological conditions

To test if habitat could shape shell features of freshwater turtles starting from birth, we tested hatchlings of Emys orbicularis, randomly chosen from four clutches of the same locality, under two treatments, stagnant (pond habitat) vs lotic (river habitat) water regimes. Due to mortality at the beginning of the experiment, we finally considered only two clutches. Turtle shells were characterized initially at hatching and then after one year of treatment by means of traditional and geometric morphometrics, and phenotypic trajectories analyses were conducted on both types of data. Carapace growth was isometric both in proportion and shape, while plastron showed an allometric pattern: length increased more than width, while the contour showed an expansion at the rear and a compression of the front. The hydrodynamic conditions during growth did not seem to affect the phenotypic trajectories of the shell proportions or the plastron. On the contrary, a significant effect was found on the phenotypic trajectory of the carapace: the size component (but not the angle one) was positively influenced by the "lentic" treatment, suggesting a different growth rate between the two environmental conditions

Stable or plastic body shape? Emys orbicularis hatchlings-juveniles growth patterns under different ecological conditions.

To test if habitat could shape shell features of freshwater turtles starting from birth, we tested hatchlings of Emys orbicularis, randomly chosen from four clutches of the same locality, under two treatments, firm (pond habitat) vs running (river habitat) water regimes. Due to mortality at the beginning of the experiment, we finally considered only two clutches. Turtle shells were characterized at hatch and after one year of treatment by means of traditional and geometric morphometrics and phenotypic trajectories analysis were conducted on both types of data. Carapace growth was isometric both in proportion and shape, while plastron showed an allometric pattern: length increased more than width while the contour showed an expansion of the rear part and a compression of the front one. The hydrodynamic conditions during growth did not seem to affect the phenotypic trajectories of shell proportions nor those of plastron. On the contrary a significant effect was found on the phenotypic trajectory of carapace: the size component (but not the angle one) was positively influenced by the “pond” treatment, suggesting a different growth rate between the two environmental conditions. Hypotheses on possible ecological constraints derived from habitat conditions are presented and discussed

Growth, longevity and age at maturity in the European whip snakes, Hierophis viridiflavus and H. carbonarius

Age and size at maturity are major life history traits, because they influence lifetime fecundity. They represent the outcome from complex interactions among environmental pressures (abiotic and biotic) and individual characteristics. They are also difficult to measure in natural populations and thus they are rarely appraised, especially in reptiles due to the elusive nature of juveniles. Using skeletochronology to circumvent these difficulties, this study aims to compare age structures, longevity, age-size relationships, growth curves, age and size at maturation and potential reproductive lifespan in three populations of the European whip snake (two Hierophis viridiflavus, one H. carbonarius). We measured the body size and counted the skeletal growth marks on 132 specimens, accidentally killed or from museum collections (72 from NW France [Chizé]; 28 from Tuscan Archipelago [Montecristo], Italy; 32 from S Italy [Calimera]). General patterns of age at maturity and longevity were consistent with previous studies based on recapture investigations. Strong differences among populations suggest local adaptation to contrasted environmental conditions. These results suggest that skeletochronology is a useful technique that can be applied opportunistically in snakes (e.g. using road-kills) in order to collect otherwise unavailable data that are essential to address fundamental questions regarding longevity, life-history traits and to perform population viability analyses

Subjective resource value affects aggressive behavior independently of resource-holding-potential and color morphs in male common wall lizard

AbstractGame theory models predict the outcome of a dyadic contest to depend on opponents' asymmetries in three main traits: resource-holding potential (RHP), resource value (RV) and aggressiveness. Using male common wall lizards Podarcis muralis, a polymorphic species showing three discrete morphs (white, yellow, and red), we investigated how the aggressive behavior varies according to a change in subjective RV and color morphs, while controlling for the asymmetry in RHP (using mirrors). By comparing the aggression of the same individual towards its mirror image in two different arenas (familiar = high subjective RV; novel = low subjective RV), we showed that lizard aggressive behavior was more intense and prolonged in the familiar arena than in the new one, thus supporting the occurrence of a direct relationship between motivation and aggression in this species. We also found the overall aggressiveness to differ from individual to individual, supporting the general hypothesis that aggressiveness is a trait associated with personality. By contrast, no effect of morphs was detected, ruling out the occurrence of morph specific variation in the aggressiveness. Our results highlight that an individual's motivation and personality might be as important as RHP and RV in the resolution of animal contests

Dimorphisme sexuel, morphométrie et variation phénotypique de la Couleuvre verte et jaune Hierophis viridifl avus dans une région du centre de la Méditerranée

Animal populations living in different environments generally exhibit divergent phenotypic characteristics. In snakes, body size varies greatly among disjunct populations. The European Whip snake, Hierophis viridifl avus, is widely distributed in the western Mediterranean area, and on most of both small and large islands of the Tyrrhenian Sea. We compared biometrical patterns regarding ventral scalation, body size and head size among different samples from mainland, large islands and small islands. Sexual Size Dimorphism was very marked in the species, with males attaining larger body size and larger relative head size than females and a lower number of ventral scales. There was a clear evidence of a strong relationship between ventral scale number and the geographic origin, with smaller island snakes characterized by a signifi cantly higher number of ventral scales. This relationship was true even when considering body size, with insular snakes signifi cantly smaller than mainland ones. Our results clearly indicated a strong differentiation among the considered populations, and provided basis to clarify the relative importance of phenotype variationDimorphisme sexuel, morphométrie et variation phénotypique de la Couleuvre verte et jaune Hierophis viridiflavus dans une région du centre de la Méditerranée. - Généralement les populations animales qui vivent dans des environnements différents divergent dans leurs caractéristiques phénotypiques. Chez les serpents, la taille corporelle varie fortement entre populations disjointes. La Couleuvre verte et jaune Hierophis viridiflavus est largement distribuée en Méditerranée occidentale et sur les îles tant petites que grandes de la mer Tyrrhénienne. Nous avons comparé les patterns biométriques relatifs à l'écaillure ventrale, la taille du corps et de la tête dans divers échantillons provenant du continent, de petites et de grandes îles. Le dimorphisme sexuel est très marqué chez cette espèce, les mâles étant corporellement plus grands, avec une tête plus grosse et moins d'écailles ventrales que les femelles. Une relation forte entre le nombre d'écailles ventrales et l'origine géographique a été clairement mise en évidence, les individus provenant des petites îles étant caractérisés par un nombre significativement élevé d'écailles ventrales. Cette relation se maintient quand on prend en compte la taille corporelle, les individus insulaires étant plus petits que ceux du continent. Nos résultats indiquent clairement une forte différenciation entre les populations étudiées et éclairent l'importance relative de la variation phénotypique

Hemipenial morphology does not provide insight on mating barriers between the two main lineages of Hierophis viridiflavus (Lacépède, 1789)

Copulatory organs are a key trait in reproductive compatibility and sexual isolation. The role of male genitalia in boosting mating success is well known and is often the outcome of behavioural and biological constraints, although no clear and common interpretation about their evolution appears broadly applicable. In snakes, hemipenial morphology has often been described under the perspective of sexual selection, taking into consideration both behavioural and morphological traits of both sexes. We investigated hemipenial morphology and ornamentation in the two subspecies of Hierophis viridiflavus, a male-male combating colubrid, and compared it to the sister species H. gemonensis, to assess intraspecific variation in size of genitalia and ornamentation richness. The male intromitted organ of this species is unilobed and bulbous, with rich ornamentations consisting of basal spines and apical calyculations. We detected no statistically significant difference in hemipenial size, basal spine count, and spine length between the two subspecies, suggesting that no copulatory barrier is present between the two clades. Although hemipenial morphology and anatomy do not seem suitable to assess intraspecific variability as shown in this study, they are often highly variable at the family or genus level, suggesting that the evolution of male genitalia is linked to phylogenetic relationships and that hemipenial divergence might be correlated to lineage splitting despite not being necessarily the main cause. Future studies should be aimed at investigating hemipenial morphology and anatomy across species under the perspective of comparative phylogeny and reproductive behaviours to address thoroughly the constraints of hemipenial evolution and development

Loss of genetic diversity and increased embryonic mortality in non-native lizard populations

Many populations are small and isolated with limited genetic variation and high risk of mating with close relatives. Inbreeding depression is suspected to contribute to extinction of wild populations, but the historical and demographic factors that contribute to reduced population viability are often difficult to tease apart. Replicated introduction events in non-native species can offer insights into this problem because they allow us to study how genetic variation and inbreeding depression are affected by demographic events (e.g. bottlenecks), genetic admixture and the extent and duration of isolation. Using detailed knowledge about the introduction history of 21 nonnative populations of the wall lizard Podarcis muralis in England, we show greater loss of genetic diversity (estimated from microsatellite loci) in older populations and in populations from native regions of high diversity. Loss of genetic diversity was accompanied by higher embryonic mortality in non-native populations, suggesting that introduced populations are sufficiently inbred to jeopardize long-term viability. However, there was no statistical correlation between population-level genetic diversity and average embryonic mortality. Similarly, at the individual level, there was no correlation between female heterozygosity and clutch size, infertility or hatching success, or between embryo heterozygosity and mortality. We discuss these results in the context of human-mediated introductions and how the history of introductions can play a fundamental role in influencing individual and population fitness in non-native species