Hidden in the sand: Phylogenomics unravel an unexpected evolutionary history for the desert-adapted vipers of the genus Cerastes.

The desert vipers of the genus Cerastes are a small clade of medically important venomous snakes within the family Viperidae. According to published morphological and molecular studies, the group is comprised by four species: two morphologically similar and phylogenetically sister taxa, the African horned viper (Cerastes cerastes) and the Arabian horned viper (Cerastes gasperettii); a more distantly related species, the Saharan sand viper (Cerastes vipera), and the enigmatic Böhme's sand viper (Cerastes boehmei), only known from a single specimen in captivity allegedly captured in Central Tunisia. In this study, we sequenced one mitochondrial marker (COI) as well as genome-wide data (ddRAD sequencing) from 28 and 41 samples, respectively, covering the entire distribution range of the genus to explore the population genomics, phylogenomic relationships and introgression patterns within the genus Cerastes. Additionally, and to provide insights into the mode of diversification of the group, we carried out niche overlap analyses considering climatic and habitat variables. Both nuclear phylogenomic reconstructions and population structure analyses have unveiled an unexpected evolutionary history for the genus Cerastes, which sharply contradicts the morphological similarities and previously published mitochondrial approaches. Cerastes cerastes and C. vipera are recovered as sister taxa whilst C. gasperettii is a sister taxon to the clade formed by these two species. We found a relatively high niche overlap (OI > 0.7) in both climatic and habitat variables between C. cerastes and C. vipera, contradicting a potential scenario of sympatric speciation. These results are in line with the introgression found between the northwestern African populations of C. cerastes and C. vipera. Finally, our genomic data confirms the existence of a lineage of C. cerastes in Arabia. All these results highlight the importance of genome-wide data over few genetic markers to study the evolutionary history of species.

Piecing the barcoding puzzle of Palearctic water frogs (Pelophylax) sheds light on amphibian biogeography and global invasions.

Palearctic water frogs (genus Pelophylax) are an outstanding model in ecology and evolution, being widespread, speciose, either threatened or threatening to other species through biological invasions, and capable of siring hybrid offspring that escape the rules of sexual reproduction. Despite half a century of genetic research and hundreds of publications, the diversity, systematics and biogeography of Pelophylax still remain highly confusing, in no small part due to a lack of correspondence between studies. To provide a comprehensive overview, we gathered >13,000 sequences of barcoding genes from >1700 native and introduced localities and built multigene mitochondrial (~17 kb) and nuclear (~10 kb) phylogenies. We mapped all currently recognized taxa and their phylogeographic lineages (>40) to get a grasp on taxonomic issues, cyto-nuclear discordances, the genetic makeup of hybridogenetic hybrids, and the origins of introduced populations. Competing hypotheses for the molecular calibration were evaluated through plausibility tests, implementing a new approach relying on predictions from the anuran speciation continuum. Based on our timetree, we propose a new biogeographic paradigm for the Palearctic since the Paleogene, notably by attributing a prominent role to the dynamics of the Paratethys, a vast paleo-sea that extended over most of Europe. Furthermore, our results show that distinct marsh frog lineages from Eastern Europe, the Balkans, the Near East, and Central Asia (P. ridibundus ssp.) are naturally capable of inducing hybridogenesis with pool frogs (P. lessonae). We identified 14 alien lineages (mostly of P. ridibundus) over ~20 areas of invasions, especially in Western Europe, with genetic signatures disproportionally pointing to the Balkans and Anatolia as the regions of origins, in line with exporting records of the frog leg industry and the stocks of pet sellers. Pelophylax thus emerges as one of the most invasive amphibians worldwide, and deserves much higher conservation concern than currently given by the authorities fighting biological invasions.

Testing Fraternal Birth Order Effects and Antagonistic Effects for Homosexual Men: Power Comparison of Various Methods.

Research on the biological determinants of male homosexual preference has long realized that the older brother effect (FBOE, i.e., a higher fraternal birth rank of homosexuals) and the antagonist effect (AE, i.e., more fertile women have a higher chance of having a homosexual son) can both generate family data where homosexual men have more siblings and more older siblings than heterosexual men. Various statistical approaches were proposed in the recent literature to evaluate whether the action of FBOE or AE could be discriminated from empirical data, by controlling for the other effect. Here, we used simulated data to formally compare all the approaches that we could find in the relevant literature for their ability to reject the null hypothesis in the presence of a specified alternative hypothesis (tests based on regression, Bayesian modeling, or contingency tables). When testing for the FBOE, the relative performance of the different tests was different depending on the specific function generating the older brother effect. Even if no tests were found to always perform better than the others, some tests performed systematically poorly, and some tests displayed a systematic high rate of type-I error. For testing the AE, the relative performance of the tests was generally not changed across all parameter values assayed, providing a clear ranking of the various proposed approaches. Pros and cons for each candidate test are discussed, taking into consideration power and the rate of type-I error but also practicability, the possibility to control for confounding variables, and to consider alternative hypotheses.

Mass of genes rather than master genes underlie the genomic architecture of amphibian speciation.

The genetic architecture of speciation, i.e., how intrinsic genomic incompatibilities promote reproductive isolation (RI) between diverging lineages, is one of the best-kept secrets of evolution. To directly assess whether incompatibilities arise in a limited set of large-effect speciation genes, or in a multitude of loci, we examined the geographic and genomic landscapes of introgression across the hybrid zones of 41 pairs of frog and toad lineages in the Western Palearctic region. As the divergence between lineages increases, phylogeographic transitions progressively become narrower, and larger parts of the genome resist introgression. This suggests that anuran speciation proceeds through a gradual accumulation of multiple barrier loci scattered across the genome, which ultimately deplete hybrid fitness by intrinsic postzygotic isolation, with behavioral isolation being achieved only at later stages. Moreover, these loci were disproportionately sex linked in one group (Hyla) but not in others (Rana and Bufotes), implying that large X-effects are not necessarily a rule of speciation with undifferentiated sex chromosomes. The highly polygenic nature of RI and the lack of hemizygous X/Z chromosomes could explain why the speciation clock ticks slower in amphibians compared to other vertebrates. The clock-like dynamics of speciation combined with the analytical focus on hybrid zones offer perspectives for more standardized practices of species delimitation.

Hybridization in late stages of speciation: Strong but incomplete genome-wide reproductive isolation and 'large Z-effect' in a moving hybrid zone.

In organisms reproducing sexually, speciation occurs when increasing divergence results in pre- or post-zygotic reproductive isolation between lineages. Studies focusing on reproductive isolation origin in early stages of speciation are common and many rely on genomic scans to infer introgression providing limited information on the genomic architecture of reproductive isolation long-term maintenance. This study analyses a natural hybrid zone between two species in a late stage of speciation. We used ddRADseq genotyping in the contact between Podarcis bocagei and P. carbonelli to examine admixture extent, analyse hybrid zone stability and assess genome-wide variation in selection against introgression. We confirmed strong but incomplete reproductive isolation in a bimodal hybrid zone. New findings revealed population genetic structure within P. carbonelli in the contact zone; geographical and genomic clines analysis suggested strong selection against gene flow, but a relatively small proportion of the loci can introgress, mostly within the narrow contact zone. However, geographical clines revealed that a few introgressed loci show signs of potential positive selection, particularly into P. bocagei. Geographical clines also detected a signal of hybrid zone movement towards P. bocagei distribution. Genomic cline analysis revealed heterogeneous patterns of introgression among loci within the syntopy zone, but the majority maintain a strong association with the genomic background of origin. However, incongruences between both cline approaches were found, potentially driven by confounding effects on genomic clines. Last, an important role of the Z chromosome in reproductive isolation is suggested. Importantly, overall patterns of restricted introgression seem to result from numerous strong intrinsic barriers across the genome.

Widespread introgression of MHC genes in Iberian Podarcis lizards.

Major histocompatibility complex (MHC) genes are crucial for the adaptive immune response of jawed vertebrates. Their variation, reaching extreme levels, is driven mainly by an arms race between hosts and pathogens. One hypothesised mechanism contributing to MHC polymorphism is adaptive introgression, the exchange of genetic variants between hybridising species favoured by selection, yet its effect on MHC variation is poorly understood. Detection of adaptive MHC introgression, though challenging, may be facilitated by the analysis of species complexes forming multiple hybrid zones. Here, we investigated MHC introgression in six hybrid zones formed by seven species of Podarcis lizards inhabiting the Iberian Peninsula. To differentiate adaptive introgression from neutral introgression, we compared the patterns of gene exchange in MHC and genome-wide markers. We found elevated sharing of MHC alleles in the proximity of contact beyond the areas of detectable genome-wide admixture in most hybrid zones and, in half of them, asymmetric MHC exchange. In general, the elevated MHC allele sharing between species pairs with abutting ranges compared to geographically isolated species pairs also supports the prevalence of introgression. Collectively, our results demonstrate widespread MHC introgression in the Iberian Podarcis complex and suggest its adaptiveness. Contrary to previous results from Triturus newts, we did not observe differences in the rate of introgression between MHC classes. Our work adds support to the emerging view of adaptive introgression as a key mechanism shaping MHC diversity. It also raises questions about the effect of elevated MHC variation and factors leading to the asymmetry of adaptive introgression.

Genomic phylogeography illuminates deep cyto-nuclear discordances in midwife toads (Alytes).

The advent of genomic methods allows us to revisit the evolutionary history of organismal groups for which robust phylogenies are still lacking, particularly in species complexes that frequently hybridize. In this study, we conduct RAD-sequencing (RAD-seq) analyses of midwife toads (genus Alytes), an iconic group of western Mediterranean amphibians famous for their parental care behavior, but equally infamous for the difficulties to reconstruct their evolutionary history. Through admixture and phylogenetic analyses of thousands of loci, we provide a comprehensive phylogeographic framework for the A. obstetricans complex, as well as a fully resolved phylogeny for the entire genus. As part of this effort, we carefully explore the influence of different sampling schemes and data filtering thresholds on tree reconstruction, showing that several, slightly different, yet robust topologies may be retrieved with small datasets obtained by stringent SNP calling parameters, especially when admixed individuals are included. In contrast, analyses of incomplete but larger datasets converged on the same phylogeny, irrespective of the reconstruction method used or the proportion of missing data. The Alytes tree features three Miocene-diverged clades corresponding to the proposed subgenera Ammoryctis (A. cisternasii), Baleaphryne (A. maurus, A. dickhilleni and A. muletensis), and Alytes (A. obstetricans complex). The latter consists of six evolutionary lineages, grouped into three clades of Pliocene origin, and currently delimited as two species: (1) A. almogavarii almogavarii and A. a. inigoi; (2) A. obstetricans obstetricans and A. o. pertinax; (3) A. o. boscai and an undescribed taxon (A. o. cf. boscai). These results contradict the mitochondrial tree, due to past mitochondrial captures in A. a. almogavarii (central Pyrenees) and A. o. boscai (central Iberia) by A. obstetricans ancestors during the Pleistocene. Patterns of admixture between subspecies appear far more extensive than previously assumed from microsatellites, causing nomenclatural uncertainties, and even underlying the reticulate evolution of one taxon (A. o. pertinax). All Ammoryctis and Baleaphryne species form shallow clades, so their taxonomy should remain stable. Amid the prevalence of cyto-nuclear discordance among terrestrial vertebrates and the usual lack of resolution of conventional nuclear markers, our study advocates for phylogeography based on next-generation sequencing, but also encourages properly exploring parameter space and sampling schemes when building and analyzing genomic datasets.

A lot of convergence, a bit of divergence: Environment and interspecific interactions shape body colour patterns in Lissotriton newts.

Coexistence with related species poses evolutionary challenges to which populations may react in diverse ways. When exposed to similar environments, sympatric populations of two species may adopt similar phenotypic trait values. However, selection may also favour trait divergence as a way to reduce competition for resources or mates. The characteristics of external body parts, such as coloration and external morphology, are involved to varying degrees in intraspecific signalling as well as in the adaptation to the environment and consequently may be diversely affected by interspecific interactions in sympatry. Here, we studied the effect of sympatry on various colour and morphological traits in males and females of two related newt species Lissotriton helveticus and L. vulgaris. Importantly, we did not only estimate how raw trait differences between species respond to sympatry, but also the marginal responses after controlling for environmental variation. We found that dorsal and caudal coloration converged in sympatry, likely reflecting their role in adaptation to local environments, especially concealment from predators. In contrast, aspects of male and female ventral coloration, which harbours sexual signals in both species, diverged in sympatry. This divergence may reduce opportunities for interspecific sexual interactions and the associated loss of energy, suggesting reproductive character displacement (RCD). Our study emphasizes the contrasting patterns of traits involved in different functions and calls for the need to consider this diversity in evolutionary studies.

Nuclear phylogenies and genomics of a contact zone establish the species rank of Podarcis lusitanicus (Squamata, Lacertidae).

Unravelling when divergent lineages constitute distinct species can be challenging, particularly in complex scenarios combining cryptic diversity and phylogenetic discordances between different types of molecular markers. Combining a phylogenetic approach with the study of contact zones can help to overcome such difficulties. The Podarcis hispanicus species complex has proven to be prosperous in independent evolutionary units, sometimes associated with cryptic diversity. Previous studies have revealed that one of the species of this complex, P. guadarramae, comprises two deeply divergent yet morphologically indistinguishable evolutionary units, currently regarded as subspecies (P. g. guadarramae and P. g. lusitanicus). In this study we used molecular data to address the systematics of the two lineages of Podarcis guadarramae and the closely related P. bocagei. Firstly, we reconstructed the species tree of these three and two additional taxa based on 30 nuclear loci using the multispecies coalescent with and without gene flow. Secondly, we used SNPs obtained from RADseq data to analyze the population structure across the distribution limits P. g. lusitanicus and P. g. guadarramae, and for comparison, a contact zone between P. bocagei and P. g. lusitanicus. Nuclear phylogenetic relationships between these three taxa are clearly difficult to determine due to the influence of gene flow, but our results give little support to the monophyly of P. guadarramae, potentially due to a nearly simultaneous divergence between them. Genetic structure and geographic cline analysis revealed that the two lineages of P. guadarramae replace each other abruptly across the sampled region and that gene flow is geographically restricted, implying the existence of strong reproductive isolation. Podarcis bocagei and P. g. lusitanicus show a similar degree of genetic differentiation and reproductive isolation, with very low levels of admixture in syntopy. These results support that all three forms are equally differentiated and reproductively isolated. In consequence, we conclude that the two former subspecies of Podarcis guadarramae constitute valid, yet cryptic species, that should be referred to as P. lusitanicus and P. guadarramae.

Systematics, biogeography and evolution of the Saharo-Arabian naked-toed geckos genus Tropiocolotes.

Plate tectonics constitute one of the main mechanisms of biological diversification on Earth, often being associated with cladogenetic events at different phylogenetic levels, as well as with exchange of faunas and floras across previously isolated biogeographic regions. North Africa and Arabia share a complex geological history that dates back to the break-up of the Arabian plate from the African plate ~30-25 Mya, followed by various geological events, such as the formation of the Red Sea or the connection between the African, Arabian and Eurasian plates. Species with Saharo-Arabian distributions have shown a close association between their evolutionary history and these geological events. In this study, we investigate the systematics, biogeography and evolution of the genus Tropiocolotes, a group of small ground-dwelling geckos, comprised by 12 species distributed from the Atlantic coast of North Africa to southwestern Iran. Species delimitation analyses uncovered the existence of high levels of undescribed diversity, with forms here considered at the species level including Tropiocolotes tripolitanus (Mauritania and southern Morocco), T. nattereri (southern Israel) and T. scorteccii (Yemen and Oman). Phylogenetic and biogeographic analyses recovered two main clades, an exclusively African clade and a Saharo-Arabian clade, that split ~25 Mya following the vicariant event mediated by the separation of the Arabian and African plates. The complex geological activity around the Red Sea is associated with the diversification within the Saharo-Arabian clade, including the colonization of North Africa from a second Tropiocolotes group. Results also provide new insights into the geographic distribution of Tropiocolotes nubicus, previously considered as exclusively associated to the Nile River valley, extending its known distribution further west, up to the Central Mountains of the Sahara. Accordingly, the Nile River seems to act as a major biogeographic barrier, separating Tropiocolotes nubicus and T. steudneri in their western and eastern margins, respectively.

Variable levels of introgression between the endangered Podarcis carbonelli and highly divergent congeneric species.

Recent empirical studies have demonstrated that speciation with gene flow is more common than previously thought. From a conservation perspective, the potential negative effects of hybridization raise concerns on the genetic integrity of endangered species. However, introgressive hybridization has also been growingly recognized as a source of diversity and new advantageous alleles. Carbonell's wall lizard (Podarcis carbonelli) is an endangered species whose distribution overlaps with four other congeneric species. Our goal here was to determine whether P. carbonelli is completely reproductively isolated from its congeners and to evaluate the relevance of hybridization and interspecific gene flow for developing a conservation plan. We used restriction site associated DNA (RAD) sequencing to discover SNPs in samples from four contact zones between P. carbonelli and four other species. Principal component analysis, multilocus genotype assignment and interspecific heterozygosity suggest incomplete reproductive isolation and ongoing gene flow between species. However, hybridization dynamics vary across all pairs, suggesting complex interactions between multiple intrinsic and extrinsic barriers. Despite seemingly ubiquitous interspecific gene flow, we found evidence of strong reproductive isolation across most contact zones. Instead, indirect effects of hybridization like waste of reproductive effort in small isolated populations may be more problematic. Our results highlight the need to further evaluate the consequences of introgression for P. carbonelli, both on a geographic and genomic level and included in a comprehensive and urgently needed conservation plan. Besides, those findings will add important insights on the potential effects of hybridization and introgression for endangered species.

Looking for Mimicry in a Snake Assemblage Using Deep Learning.

Batesian mimicry is a canonical example of evolution by natural selection, popularized by highly colorful species resembling unrelated models with astonishing precision. However, Batesian mimicry could also occur in inconspicuous species and rely on subtle resemblance. Although potentially widespread, such instances have been rarely investigated, such that the real frequency of Batesian mimicry has remained largely unknown. To fill this gap, we developed a new approach using deep learning to quantify the visual resemblance between putative mimics and models from photographs. We applied this method to Western Palearctic snakes. Potential nonvenomous mimics were revealed by an excess of resemblance to sympatric venomous snakes compared with random expectations. We found that 8% of the nonvenomous species were potential mimics, although they resembled their models imperfectly. This study is the first to quantify the frequency of Batesian mimicry in a whole community of vertebrates, and it shows that even concealed species can act as potential models. Our approach should prove useful for detecting mimicry in other communities, and more generally it highlights the benefits of deep learning for quantitative studies of phenotypic resemblance.

Integrating hybrid zone analyses in species delimitation: lessons from two anuran radiations of the Western Mediterranean.

Molecular ecologists often rely on phylogenetic evidence for assessing the species-level systematics of newly discovered lineages. Alternatively, the extent of introgression at phylogeographic transitions can provide a more direct test to assign candidate taxa into subspecies or species categories. Here, we compared phylogenetic versus hybrid zone approaches of species delimitation in two groups of frogs from the Western Mediterranean region (Discoglossus and Pelodytes), by using genomic data (ddRAD). In both genera, coalescent analyses recovered almost all nominal taxa as "species". However, the least-diverged pairs D. g. galganoi/jeanneae and P. punctatus/hespericus admix over hundreds of kilometers, suggesting that they have not yet developed strong reproductive isolation and should be treated as conspecifics. In contrast, the comparatively older D. scovazzi/pictus and P. atlanticus/ibericus form narrow contact zones, consistent with species distinctiveness. Due to their complementarity, we recommend taxonomists to combine phylogenomics with hybrid zone analyses to scale the gray zone of speciation, i.e., the evolutionary window separating widely admixing lineages versus nascent reproductively isolated species. The radically different transitions documented here conform to the view that genetic incompatibilities accumulating with divergence generate a weak barrier to gene flow for long periods of time, until their effects multiply and the speciation process then advances rapidly. Given the variability of the gray zone among taxonomic groups, at least from our current abilities to measure it, we recommend to customize divergence thresholds within radiations to categorize lineages for which no direct test of speciation is possible.

Examining the link between relaxed predation and bird coloration on islands.

Insular ecosystems share analogous ecological conditions, leading to patterns of convergent evolution that are collectively termed as the 'island syndrome'. In birds, part of this syndrome is a tendency for a duller plumage, possibly as a result of relaxed sexual selection. Despite this global pattern, some insular species display a more colourful plumage than their mainland relatives, but why this occurs has remained unexplained. Here, we examine the hypothesis that these cases of increased plumage coloration on islands could arise through a relaxation of predation pressure. We used comparative analyses to investigate whether average insular richness of raptors of suitable mass influences the plumage colourfulness and brightness across 110 pairs of insular endemic species and their closest mainland relatives. As predicted, we find a likely negative relationship between insular coloration and insular predation while controlling for mainland predation and coloration, suggesting that species were more likely to become more colourful as the number of insular predators decreased. By contrast, plumage brightness was not influenced by predation pressure. Relaxation from predation, together with drift, might thus be a key mechanism of species phenotypic responses to insularity.

Phylogeography of a cryptic speciation continuum in Eurasian spadefoot toads (Pelobates).

Cryptic phylogeographic diversifications provide unique models to examine the role of phylogenetic divergence on the evolution of reproductive isolation, without extrinsic factors such as ecological and behavioural differentiation. Yet, to date very few comparative studies have been attempted within such radiations. Here, we characterize a new speciation continuum in a group of widespread Eurasian amphibians, the Pelobates spadefoot toads, by conducting multilocus (restriction site associated DNA sequencing and mitochondrial DNA) phylogenetic, phylogeographic and hybrid zone analyses. Within the P. syriacus complex, we discovered species-level cryptic divergences (>5 million years ago [My]) between populations distributed in the Near-East (hereafter P. syriacus sensu stricto [s.s.]) and southeastern Europe (hereafter P. balcanicus), each featuring deep intraspecific lineages. Altogether, we could scale hybridizability to divergence time along six different stages, spanning from sympatry without gene flow (P. fuscus and P. balcanicus, >10 My), parapatry with highly restricted hybridization (P. balcanicus and P. syriacus s.s., >5 My), narrow hybrid zones (~15 km) consistent with partial reproductive isolation (P. fuscus and P. vespertinus, ~3 My), to extensive admixture between Pleistocene and refugial lineages (≤2 My). This full spectrum empirically supports a gradual build up of reproductive barriers through time, reversible up until a threshold that we estimate at ~3 My. Hence, cryptic phylogeographic lineages may fade away or become reproductively isolated species simply depending on the time they persist in allopatry, and without definite ecomorphological divergence.

Diversification and speciation in tree frogs from the Maghreb (Hyla meridionalis sensu lato), with description of a new African endemic.

Comparative molecular studies emphasized a new biogeographic paradigm for the terrestrial fauna of North Africa, one of the last uncharted ecoregions of the Western Palearctic: two independent east-west divisions across the Maghreb. Through a comprehensive phylogeography, we assessed how this model suits the genetic diversification documented for the tree frog Hyla meridionalis sensu lato. Analyses of mtDNA variation and thousands of nuclear loci confirmed the old split (low-Pliocene) between Tunisian and Algerian populations. These lineages meet but barely admix in the eastern Maghreb (Algerian-Tunisian border), a sign of putatively advanced reproductive isolation. In the western Maghreb, we report a Pleistocene divergence between Moroccan and Algerian populations. Tree frogs thus follow both predictions: a double east-west break that gave rise to two suture zones characteristic of North-African phylogeography. Moreover, some intraspecific mtDNA variation is not mirrored by the nuclear data, emphasizing that evolutionary units should always be designated by multilocus approaches. Last but not least, we describe the Tunisian lineage as a new species endemic to Africa.

Ancient diversification, biogeography, and the role of climatic niche evolution in the Old World cat snakes (Colubridae, Telescopus).

The process of species diversification is often associated with niche shifts in the newly arising lineages so that interspecific competition is minimized. However, an opposing force known as niche conservatism causes that related species tend to resemble each other in their niche requirements. Due to the inherent multidimensionality of niche space, some niche components may be subject to divergent evolution while others remain conserved in the process of speciation. One such possible component is the species' climatic niche. Here, we test the role of climatic niche evolution on the diversification of the Old World cat snakes of the genus Telescopus. These slender, nocturnal snakes are distributed in arid and semiarid areas throughout Africa, southwest Asia and adjoining parts of Europe. Because phylogenetic relationships among the Telescopus species are virtually unknown, we generated sequence data for eight genetic markers from ten of the 14 described species and reconstructed a time-calibrated phylogeny of the genus. Phylogenetic analysesindicate that the genus is of considerably old origin that dates back to the Eocene/Oligocene boundary. Biogeographical analyses place the ancestor of the genus in Africa, where it diversified into the species observed today and from where it colonized Arabia and the Levant twice independently. The colonization of Arabia occurred in the Miocene, that of the Levant either in the Late Oligocene or Early Miocene. We then identified temperature and precipitation niche space and breadth of the species included in the phylogeny and examined whether there is phylogenetic signal in these climatic niche characteristics. Despite the vast range of the genus and its complex biogeographic history, most Telescopus species have similar environmental requirements with preference for arid to semiarid conditions. One may thus expect that the genus' climatic niche will be conserved. However, our results suggest that most of the climatic niche axes examined show no phylogenetic signal, being indicative of no evolutionary constraints on the climatic niche position and niche breadth in Telescopus. The only two variables with positive phylogenetic signal (temperature niche position and precipitation niche breadth) evolved under the Brownian motion model, also indicating no directional selection on these traits. As a result, climatic niche evolution does not seem to be the major driver for the diversification in Telescopus.

The role of climatic cycles and trans-Saharan migration corridors in species diversification: Biogeography of Psammophis schokari group in North Africa.

Highlands, hydrographic systems and coastal areas have been hypothesised to form corridors across the hyperarid Sahara desert in North Africa, allowing dispersal and gene flow for non-xeric species. Here we aim to provide a genetic test for the trans-Saharan corridor model, and predict the location and stability of ecological-corridors, by combining phylogeography and palaeoclimatic modelling. The model was the Psammophis schokari (Schokari sand racer) group, fast-moving and widely distributed generalist colubrids occurring mostly in arid and semiarid scrublands. We combined dated phylogenies of mitochondrial and nuclear markers with palaeoclimatic modelling. For the phylogeographic analysis, we used 75 samples of P. schokari and P. aegyptius, and Bayesian and Maximum-Likelihood methods. For the ecological models, we used Maxent over the distribution of P. schokari and West African lineages. Models were projected to past conditions (mid Holocene, Last Glacial Maximum and Last Inter-Glacial) to infer climatic stable areas. Climatic stability was predicted to be mostly restricted to coastal areas and not spatially continuous. A putative temporary trans-Saharan corridor was identified in Eastern Sahara, with a more stable one along the Atlantic coast. Six parapatric lineages were identified within P. schokari, four occurring in North Africa. These likely diverged during the Pliocene. The Tamanraset River might have been a vicariant agent. African lineages may have experienced further subsequent diversification during the late Pleistocene. The main P. schokari refugia were probably located along the northern margins of the Sahara, allowing its North-to-South colonization. Trans-Saharan corridors seem to have played a role in P. schokari biogeography, allowing colonization of central Saharan mountains and Sahel. Some might have worked as refugia, and even the most stable corridors may have sections working as filters, depending on each climatic phase. We expect the use of trans-Saharan corridors to decrease for more mesic species or with less dispersal capabilities.

Kin Selection and Male Homosexual Preference in Indonesia.

Male homosexual preference (MHP) challenges evolutionary thinking because the preference for male-male relationships is heritable, implies a fertility cost (lower offspring number), and is relatively frequent in some societies (2-6% in Western countries) for a costly trait. It has been proposed that individuals with a MHP counterbalance reproductive costs through the transfer of resources to kin, thereby improving their indirect reproduction through kin's reproductive success. This kin selection hypothesis is not supported in Western countries and Japan, although consistent evidence has been obtained in Samoa. In this study, data from Java (Indonesia) were obtained to assess the avuncular tendencies of men with contrasting sexual orientation to measure possible resource transfer. Consistent with the kin selection hypothesis, males with a homosexual orientation reported an increased willingness to transfer resources toward nephews and nieces and declared having transferred more money to nephews and nieces. We developed a method to quantitatively estimate the contribution of kin selection on inclusive reproduction associated to sexual orientation, taking into account various possible biases. Kin selection reduced the direct reproductive cost of homosexual men by 20%, so suggesting that kin selection alone is insufficient to explain the maintenance of male homosexuality. Other potential factors are discussed, as well as the limitations of the study and the social determinant operating for the expression of increased avuncular tendencies of homosexual men.