New provincial records of skinks (Squamata: Scincidae) from northwestern Vietnam.
ABSTRACT: We report six new records of skinks from northwestern Vietnam: Eutropis macularius, Scincelladevorator , S.monticola, S.ochracea, Sphenomorphuscryptotis and S.indicus. Our new findings increase the species number of skinks (Scincidae) to nine in Dien Bien Province and to 14 in Son La Province. We also provide additional natural history data of aforementioned species.
Project description:BACKGROUND:The evolution of South American Mabuyinae skinks holds significant biogeographic interest because its sister lineage is distributed across the African continent and adjacent islands. Moreover, at least one insular species, Trachylepis atlantica, has independently reached the New World through transoceanic dispersal. To clarify the evolutionary history of both Neotropical lineages, this study aimed to infer an updated timescale using the largest species and gene sampling dataset ever assembled for this group. By extending the analysis to the Scincidae family, we could employ fossil information to estimate mabuyinae divergence times and carried out a formal statistical biogeography analysis. To unveil macroevolutionary patterns, we also inferred diversification rates for this lineage and evaluated whether the colonization of South American continent significantly altered the mode of Mabuyinae evolution. METHODS:A time-calibrated phylogeny was inferred under the Bayesian framework employing fossil information. This timetree was used to (i) evaluate the historical biogeography of mabuiyines using the statistical approach implemented in BioGeoBEARS; (ii) estimate macroevolutionary diversification rates of the South American Mabuyinae lineages and the patterns of evolution of selected traits, namely, the mode of reproduction, body mass and snout-vent length; (iii) test the hypothesis of differential macroevolutionary patterns in South American lineages in BAMM and GeoSSE; and (iv) re-evaluate the ancestral state of the mode of reproduction of mabuyines. RESULTS:Our results corroborated the hypothesis that the occupation of the South American continent by Mabuyinae consisted of two independent dispersion events that occurred between the Oligocene and the Miocene. We found significant differences in speciation rates between the New World and the remaining Mabuyinae clades only in GeoSSE. The influence of phenotypic traits on diversification rates was not supported by any method. Ancestral state reconstruction suggested that the ancestor of South American mabuyine was likely viviparous. DISCUSSION:Our analyses further corroborated the existence of a transoceanic connection between Africa and South America in the Eocene/Oligocene period (Atlantogea). Following colonization of the isolated South America and subsequent dispersal through the continent by the ancestral mabuyine stock, we detected no difference in macroevolutionary regimes of New World clades. This finding argued against the ecological opportunity model as an explanation for the diversity of living mabuyines.
Project description:African snake-eyed skinks are relatively small lizards of the genera Panaspis and Afroablepharus. Species allocation of these genera frequently changed during the 20th century based on morphology, ecology, and biogeography. Members of these genera occur primarily in savanna habitats throughout sub-Saharan Africa and include species whose highly conserved morphology poses challenges for taxonomic studies. We sequenced two mitochondrial (16S and cyt b) and two nuclear genes (PDC and RAG1) from 76 Panaspis and Afroablepharus samples from across eastern, central, and southern Africa. Concatenated gene-tree and divergence-dating analyses were conducted to infer phylogenies and biogeographic patterns. Molecular data sets revealed several cryptic lineages, with most radiations occurring during the mid-Miocene to Pliocene. We infer that rifting processes (including the formation of the East African Rift System) and climatic oscillations contributed to the expansion and contraction of savannas, and caused cladogenesis in snake-eyed skinks. Species in Panaspis and Afroablepharus used in this study, including type species for both genera, formed a monophyletic group. As a result, the latter genus should be synonymized with the former, which has priority. Conservatively, we continue to include the West African species P. breviceps and P. togoensis within an expanded Panaspis, but note that they occur in relatively divergent clades, and their taxonomic status may change with improved taxon sampling. Divergence estimates and cryptic speciation patterns of snake-eyed skinks were consistent with previous studies of other savanna vertebrate lineages from the same areas examined in this study.
Project description:Skinks are present under the Scincidae family, widely distributed species in Indian subcontinent. Uttarakhand is one of the hotspot where number of identified and unidentified skink species reported. Herein, we first time provided the 12S rRNA genetic reference database of four skink species, i.e. <i>Eutropis macularia</i>, <i>Eutropis carinata</i>, <i>Asymblepharus himalayanus</i> and <i>Lygosoma punctata</i>, in Rajaji Tiger Reserve (RTR), Uttarakhand (India). The identified four species belong to three different genera, where <i>Eutropis carinata</i> and <i>Asymblepharus himalayanus</i> listed Least Concern and Vulnerable in IUCN, respectively. Here, we collected tissue samples of four different skink species from Rajaji Tiger Reserve during field survey. After successful laboratory procedure, we compared obtained sequences with publically available genetic database and we observed four sequences matched with respective species. Furthermore, the evolutionary sequence divergence result revealed that the <i>Eutropis carinata</i> and <i>Eutropis macularia</i> are close to each other with 0.11 genetic distance. The present study indicates that the exact number and population distribution of skink species are unidentified; therefore, herein we suggest the proper screening of Uttarakhand population around should be investigated, further genetic study in combination with a good sampling strategy to investigate species biology and status for conservation program.
Project description:Skinks account for more than 25% of all lizard species; however, representatives of fewer than a quarter of all species have been characterized osteologically. All but a few of the available cranial descriptions concentrate solely on characters that can be seen externally on the intact skull. Mabuyid skinks of the genus Trachylepis are the dominant, fully limbed skinks in Sub-Saharan Africa, and nearly all species have the same generalized body plan. Although a few rock crevice-dwelling species possess slight body depression, extreme dorsoventral depression is observed only in Trachylepis laevis. We investigated the detailed skull anatomy of three Trachylepis skinks (T. laevis, T. sulcata, and T. gonwouoi, a recently described species allied to T. affinis) using high-resolution X-ray micro-computed tomography. Our goals were to review the scincid cranial osteology literature in a phylogenetic context, provide a detailed anatomical atlas for the mabuyid lineage, and investigate the morphological adaptations of the highly modified T. laevis. Our results demonstrate that there is significant morphological variation between these three taxa, including the loss and fusion of structures, as well as changes in the shape, scale, and relationship between individual elements. Trachylepis laevis possesses several osteological modifications that have produced a reducton in head depth that are likely functional consequences of extreme rupicolous habits, including a flat skull roof, many strongly recumbent elements, and a depressed neurocranium.We hypothesize these modifications may correspond to descreased bite force and increased capabilities of cranial kinesis. Our study is the first element-by-element description of a skink using computed tomography technology.
Project description:Scincine lizards in Madagascar form an endemic clade of about 60 species exhibiting a variety of ecomorphological adaptations. Several subclades have adapted to burrowing and convergently regressed their limbs and eyes, resulting in a variety of partial and completely limbless morphologies among extant taxa. However, patterns of limb regression in these taxa have not been studied in detail. Here we fill this gap in knowledge by providing a phylogenetic analysis of DNA sequences of three mitochondrial and four nuclear gene fragments in an extended sampling of Malagasy skinks, and microtomographic analyses of osteology of various burrowing taxa adapted to sand substrate. Based on our data we propose to (i) consider Sirenoscincus Sakata & Hikida, 2003, as junior synonym of Voeltzkowia Boettger, 1893; (ii) resurrect the genus name Grandidierina Mocquard, 1894, for four species previously included in Voeltzkowia; and (iii) consider Androngo Brygoo, 1982, as junior synonym of Pygomeles Grandidier, 1867. By supporting the clade consisting of the limbless Voeltzkowia mira and the forelimb-only taxa V. mobydick and V. yamagishii, our data indicate that full regression of limbs and eyes occurred in parallel twice in the genus Voeltzkowia (as hitherto defined) that we consider as a sand-swimming ecomorph: in the Voeltzkowia clade sensu stricto the regression first affected the hindlimbs and subsequently the forelimbs, whereas the Grandidierina clade first regressed the forelimbs and subsequently the hindlimbs following the pattern prevalent in squamates. Timetree reconstructions for the Malagasy Scincidae contain a substantial amount of uncertainty due to the absence of suitable primary fossil calibrations. However, our preliminary reconstructions suggest rapid limb regression in Malagasy scincids with an estimated maximal duration of 6 MYr for a complete regression in Paracontias, and 4 and 8 MYr respectively for complete regression of forelimbs in Grandidierina and hindlimbs in Voeltzkowia.
Project description:Most mammals and approximately 20% of squamates (lizards and snakes) are viviparous, whereas all crocodilians, birds and turtles are oviparous. Viviparity evolved greater than 100 times in squamates, including multiple times in Mabuyinae (Reptilia: Scincidae), making this group ideal for studying the evolution of nutritional patterns associated with viviparity. Previous studies suggest that extreme matrotrophy, the support of virtually all of embryonic development by maternal nutrients, evolved as many as three times in Mabuyinae: in Neotropical Mabuyinae (63 species), Eumecia (2 species; Africa) and Trachylepis ivensii (Africa). However, no explicit phylogenetic hypotheses exist for understanding the evolution of extreme matrotrophy. Using multilocus DNA data, we inferred a species tree for Mabuyinae that implies that T. ivensii (here assigned to the resurrected genus Lubuya) is sister to Eumecia, suggesting that extreme matrotrophy evolved only once in African mabuyine skinks.
Project description:We sequenced and annotated the nearly complete mitochondrial genome (mitogenome) of <i>Scincella reevesii</i> (Squamata: Scincidae). This mitogenome was 14,106 bp in size and encoded 13 protein-coding genes, two ribosomal RNA genes, and 22 transfer RNA genes. The most common start codon is ATG, the most common termination codon is TAA and five genes have incomplete termination codon T. The overall nucleotide composition was 32.0% of A, 14.3% of G, 26.1% of T, and 27.6% of C. The data will increase the basic information of Scincidae phylogenetic research and can help to better understand the phylogenetic status of <i>S. reevesii</i> in Squamata.
Project description:The first complete mitochondrial genome sequence was determined for an oviparous lizard, <i>Scincella modesta</i> (<i>Scincella,</i> Scincidae). The total length of the complete mitochondrial genome was 17,511 bp, encodes 13 protein-coding genes, 22 tRNAs, 2 rRNA genes, and 2 non-coding regions. The overall base composition of <i>S. modesta</i> is A: 31.9%, T: 27.2%, G: 14.5%, and C: 26.5%. Most of the <i>S. modesta</i> mitochondrial genes are encoded on the H-strand except for the ND6 gene and eight tRNA genes, which are encoded on the L-strand. Mrbayes and ML tree based on 13 protein-coding genes indicated that <i>S. vandenburghi</i> is the sister group of the <i>S. modesta</i> within the genus <i>Scincella.</i> The complete mitogenome sequence of <i>S. modesta</i> provided fundamental data for resolving phylogenetic and genetic problems related to genus <i>Scincella.</i>
Project description:We sequenced and annotated the complete mitochondrial genome (mitogenome) of <i>Scincella modesta</i> (Squamata: Scincidae). This mitogenome was 17,466 bp long and encoded 13 protein-coding genes (PCGs), 22 transfer RNA genes, 2 ribosomal RNA genes, and 2 non-coding regions. The overall nucleotide composition was 31.8% of A, 14.5% of G, 27.2% of T, and 26.5% of C. Phylogenetic analysis using Bayesian Inference (BI) validated the taxonomic status of <i>S. modesta</i>, exhibiting the close relationship with the other two species from the genus <i>Scincella</i>.