Does reproductive effort influence the metabolic rate of Tomodon dorsatus snakes?

In Squamate reptiles, vitellogenesis in females is marked by an increase in the number and size of follicles, leading to an increase in aerobic metabolism to support the rising energy demand during reproductive activity. Male gametes are smaller than female gametes, and spermiogenesis requires less energy than vitellogenesis. This investigation compares the relationship between aerobic metabolism and reproductive effort in male and female viviparous Tomodon dorsatus snakes. We evaluated the influence of the males' and females' reproductive stages, along with the masses of follicles and testicles, on their aerobic metabolic rate. Our findings show that females have higher maintenance cost of pregnancy than metabolic costs of vitellogenesis. In males, we found no evidence of the reproductive effort influencing aerobic metabolic rates. In T. dorsatus, females have a long period of development and high fecundity. Therefore, the metabolic costs of vitellogenesis represent a critical component in the reproductive effort. On the other hand, males of T. dorsatus maintain a similar mass of gonads throughout the year with constant energy demand. These results reflect the difference in reproductive efforts between females and males of T. dorsatus.     

Diet of the snake Philodryas nattereri (Steindachner, 1870) suggests a high plasticity of foraging in north-eastern Brazil

The knowledge about interactions between predators and prey is essential for understanding the natural history of animals, especially snakes, which are cryptic organisms that are difficult to visualize in the wild. This article reports on the predation of lizards, frogs, bats and venomous snakes by the snake Philodryas nattereri, evidencing its generalist feeding habits.     

HIERARCHICAL COMPARISON OF GENETIC VARIANCE-COVARIANCE MATRICES. II COASTAL-INLAND DIVERGENCE IN THE GARTER SNAKE,THAMNOPHIS ELEGANS

The time-scale for the evolution of additive genetic variance-covariance matrices (G-matrices) is a crucial issue in evolutionary biology. If the evolution of G-matrices is slow enough, we can use standard multivariate equations to model drift and selection response on evolutionary time scales. We compared the G-matrices for meristic traits in two populations of gaiter snakes (Thamnophis elegans) with an apparent separation time of 2 million years. Despite considerable divergence in the meristic traits, foraging habits, and diet, these populations show conservation of structure in their G-matrices. Using Flury's hierarchial approach to matrix comparisons, we found that the populations have retained the principal components (eigenvectors) of their G-matrices, but their eigenvalues have diverged. In contrast, we were unable to reject the hypothesis of equal environmental matrices (E-matrices) for these populations. We propose that a conserved pattern of multivariate stabilizing selection may have contributed to conservation of G- and E-matrix structure during the divergence of these populations.     

When are adaptive radiations replicated in areas? Ecological opportunity and unexceptional diversification in West Indian dipsadine snakes (Colubridae: Alsophiini)

Aim We examine diversification in Caribbean alsophiine snakes and hypothesize that, given the ecological opportunity presented by colonization of the West Indies, alsophiines should show the signature of an early burst of diversification and associated low within‐clade ecological and morphological disparification. We also test whether changes in morphology and ecology are associated with changes in diversification rate, as trait‐dependent diversification is hypothesized to affect historical inferences of diversification and disparification. Finally, as replicated radiations are found across the West Indies in the anoles, we test for significant differences in ecological and morphological assemblages and rates among the major island groups. Location The West Indies. Methods A time‐calibrated phylogeny produced from six genes using relaxed clock methods in beast was constructed to estimate ancestral areas using Lagrange . Maximum body size and ecological niche were scored for all species in the phylogeny, and comparative phylogenetic methods in R using geiger , laser , ape and our own code were used to examine diversification through time, disparification and trait‐dependent diversification from this dated phylogeny. Results The pattern of species diversification did not differ significantly from the Yule model of diversification. Morphology and ecology fitted a Brownian and white noise model of diversification, respectively. Although not significantly different, morphological disparification was lower than the Brownian null model, whereas ecological disparification was significantly greater than the null. Trait‐dependent diversification analyses suggested that the constant null models provided the best fit to these data. There was no significant signal of rate variation among the major island groups for size, but moderate evidence for niche. Main conclusions Although ecological opportunity was similarly present for alsophiines as it was for anoles, the snakes fail to show an early burst of speciation. Potential reasons for this include the young age of the group, and staggered diversification due to waiting times between island colonization. In turn, ecological and morphological disparities do not necessarily follow predictable patterns related to species diversification. Thus, the presence of ecological opportunity alone is not necessarily sufficient to trigger replicated adaptive radiations in areas.     

Evolution and phylogeny of the genus Natrix (Serpentes: Colubridae)

Some aspects of the natural history of snakes of the colubrid genus Natrix have been well studied. With their extensive European distribution and relative abundance, their ecology, reproduction and behaviour are well known. Yet other facets of their biology remain poorly understood. These include knowledge of Natrix phylogeny, hypotheses explaining the current distribution of the three extant members of the genus, and their evolution and relationships. In this study we used molecular data, the nucleotide sequences of four protein-coding mitochondrial genes (3806 bp total), to provide a well-supported phylogeny for the genus Natrix . With these molecular data, evidence from the fossil record, and knowledge of palaeogeological events, we used two approaches in designing a time scale which we used to date the major events in Natrix speciation and intraspecific variation. Our data strongly support a phylogeny for the genus in which N. maura is basal with N. natrix and N. tessellata being sister species. The calibrated molecular clock suggests that N. maura diverged from the common ancestor of the three species 18–27 mya and that N. natrix and N. tessellata diverged 13–22 mya. Although the ranges of these estimates are large they support an early Miocene to late Oligocene origin for the three species. Intraspecific divergence is estimated to have commenced 5.3, 6.0 and 6.7 mya with evolutionary rates of 1 : 1.25 : 1.35% per million years for N. maura, N. natrix and N. tessellata , respectively.  © 2006 The Linnean Society of London, Biological Journal of the Linnean Society , 2006, 87 , 127–143.     

Characterization of polymorphic microsatellite markers in the adder,Vipera berus

Microsatellite DNA markers can yield sufficient resolution for individual identification as well as provide genetic information on a larger, interpopulational scale. Here we present details on six microsatellite primer pairs developed for the adder, Vipera berus. The number of alleles found varied between 2 and 38 per locus. The objectives behind developing these markers included assessment both of paternity and population histories from different parts of the species’ range. Cross‐species amplification indicated that these markers may also be useful for studies of other species within the Viperidae family.     

Molecular phylogeny and divergence dates for Australasian elapids and sea snakes (hydrophiinae): evidence from seven genes for rapid evolutionary radiations

One of the most prolific radiations of venomous snakes, the Australo-Melanesian Hydrophiinae includes approximately 100 species of Australasian terrestrial elapids plus all approximately 60 species of viviparous sea snakes. Here, we estimate hydrophiine relationships based on a large data set comprising 5800 bp drawn from seven genes (mitochondrial: ND4, cytb, 12S, 16S; nuclear: rag1, cmos, myh). These data were analysed using parsimony, likelihood and Bayesian methods to better resolve hydrophiine phylogeny and provide a timescale for the terrestrial and marine radiations. Among oviparous forms, Cacophis, Furina and Demansia are basal to other Australian elapids (core oxyuranines). The Melanesian Toxicocalamus and Aspidomorphus group with Demansia, indicating multiple dispersal events between New Guinea and Australia. Oxyuranus and Pseudonaja form a robust clade. The small burrowing taxa form two separate clades, one consisting of Vermicella and Neelaps calanotus, and the other including Simoselaps, Brachyurophis and Neelaps bimaculatus. The viviparous terrestrial elapids form three separate groups: Acanthophis, the Rhinoplocephalus group and the Notechis-Hemiaspis group. True sea snakes (Hydrophiini) are robustly united with the Notechis-Hemiaspis group. Many of the retrieved groupings are consistent with previous molecular and morphological analyses, but the polyphyly of the viviparous and burrowing groups, and of Neelaps, are novel results. Bayesian relaxed clock analyses indicate very recent divergences: the approximately 160 species of the core Australian radiation (including sea snakes) arose within the last 10 Myr, with most inter-generic splits dating to between 10 and 6 Ma. The Hydrophis sea snake lineage is an exceptionally rapid radiation, with > 40 species evolving within the last 5 Myr.     

Description and phylogeny of three new species of Synophis (Colubridae,Dipsadinae) from the tropical Andes in Ecuador and Peru

The discovery of three new species of Synophis snakes from the eastern slopes of the tropical Andes in Ecuador and Peru is reported. All previous records of Synophis bicolor from eastern Ecuador correspond to Synophis bogerti sp. n., which occurs between 1000–1750 m along a large part of the Amazonian slopes of the Ecuadorian Andes. In contrast, Synophis zamora sp. n. is restricted to southeastern Ecuador, including Cordillera del Cóndor, between 1543–1843 m. Synophis insulomontanus sp. n. is from the eastern slopes of the Andes in central and northern Peru, between 1122–1798 m, and represents the first record of Synophis from this country. All three new species share in common a large lateral spine at the base of the hemipenial body. A molecular phylogenetic tree based on three mitochondrial genes is presented, including samples of Diaphorolepis wagneri. Our tree strongly supports Synophis and Diaphorolepis as sister taxa, as well as monophyly of the three new species described here and Synophis calamitus. Inclusion of Synophis and Diaphorolepis within Dipsadinae as sister to a clade containing Imantodes, Dipsas, Ninia, Hypsiglena and Pseudoleptodeira is also supported.     

Higher-level relationships of snakes inferred from four nuclear and mitochondrial genes

Higher-level snake relationships are inferred from sequence analyses of one nuclear gene (C-mos) and three mitochondrial genes (12S rRNA, 16S rRNA and cytochrome b). Extant snakes belong to two lineages: the fossorial Scolecophidia, which feed on small prey on a frequent basis, and the ecologically diverse Alethinophidia ('typical' snakes), which feed on large prey on an infrequent basis. The vast majority of Alethinophidia, if not all of them, belong to two clades, corresponding to two distinct prey neutralization modes: unimodal constriction for the Henophidia (locomotor and feeding systems coupled) and injection of toxic saliva, in addition (or not) to diverse alternate modes of constriction, for the Caenophidia (locomotor and feeding systems uncoupled). Within Alethinophidia, non-macrostomatan (small gape) Aniliidae (genus Anilius) and macrostomatan (large gape) Tropidophiidae (genera Trachyboa and Tropidophis), both from the Neotropics, are closest relatives. Although our data are insufficient to robustly infer the ancestral mode of life of snakes, we find evidence of plasticity in the basic ecological and trophic modes of snakes. Consequently, the macrostomatan condition should not be treated a priori as a derived character state devoid of homoplasy.