RESUMO
The present study reports the existence of cliff racer, Platyceps rhodorachis from the plains of Punjab, Pakistan. A total of 10 specimens were captured during the field surveys from June to September, 2018 from different sites of Punjab. Platyceps rhodorachis was identify on the basis of morphology and confirmed through COI gene sequences. The obtained DNA sequences have shown reliable and exact species identification. Newly produced DNA sequences of Platyceps rhodorachis were submitted to GenBank and accession numbers were obtained (MK936174.1, MK941839.1 and MT790210.1). N-J tree based on COI sequences of Platyceps rhodorachis clearly separated as out-group with other members of family Colubridae based on p-distance. The intra-specific genetic variation ranges from 12% to 18%. The DNA sequences of Platyceps rhodorachis kashmirensis, Platyceps rhodorachis ladacensis, Platyceps ventromaculatus, Platyceps ventromaculatus bengalensis and Platyceps ventromaculatus indusai are not available at NCBI to validate their taxonomic positions. In our recommendations, a large scale molecular based identification of Pakistans herpetofauna is required to report more new or subspecies from country.
O presente estudo relata a existência de um corredor de penhasco, Platyceps rhodorachis, das planícies de Punjab, Paquistão. Um total de 10 espécimes foi capturado durante os levantamentos de campo de junho a setembro de 2018 em diferentes locais de Punjab. Platyceps rhodorachis foi identificada com base na morfologia e confirmada por meio de sequências do gene COI. As sequências de DNA obtidas mostraram identificação de espécies confiável e exata. Sequências de DNA de Platyceps rhodorachis recém-produzidas foram submetidas ao GenBank e os números de acesso foram obtidos (MK936174.1, MK941839.1 e MT790210.1). Árvore N-J baseada em sequências COI de Platyceps rhodorachis claramente separadas como out-group com outros membros da família Colubridae com base na distância-p. A variação genética intraespecífica varia de 12% a 18%. As sequências de DNA de Platyceps rhodorachis kashmirensis, Platyceps rhodorachis ladacensis, Platyceps ventromaculatus, Platyceps ventromaculatus bengalensis e Platyceps ventromaculatus indusai não estão disponíveis no NCBI para validar suas posições taxonômicas. Em nossas recomendações, uma identificação de base molecular em grande escala da herpetofauna do Paquistão é necessária para relatar mais novas ou subespécies do país.
Assuntos
Animais , Serpentes/anatomia & histologia , Serpentes/genéticaRESUMO
The present study reports the existence of cliff racer, Platyceps rhodorachis from the plains of Punjab, Pakistan. A total of 10 specimens were captured during the field surveys from June to September, 2018 from different sites of Punjab. Platyceps rhodorachis was identify on the basis of morphology and confirmed through COI gene sequences. The obtained DNA sequences have shown reliable and exact species identification. Newly produced DNA sequences of Platyceps rhodorachis were submitted to GenBank and accession numbers were obtained (MK936174.1, MK941839.1 and MT790210.1). N-J tree based on COI sequences of Platyceps rhodorachis clearly separated as out-group with other members of family Colubridae based on p-distance. The intra-specific genetic variation ranges from 12% to 18%. The DNA sequences of Platyceps rhodorachis kashmirensis, Platyceps rhodorachis ladacensis, Platyceps ventromaculatus, Platyceps ventromaculatus bengalensis and Platyceps ventromaculatus indusai are not available at NCBI to validate their taxonomic positions. In our recommendations, a large scale molecular based identification of Pakistans herpetofauna is required to report more new or subspecies from country.(AU)
O presente estudo relata a existência de um corredor de penhasco, Platyceps rhodorachis, das planícies de Punjab, Paquistão. Um total de 10 espécimes foi capturado durante os levantamentos de campo de junho a setembro de 2018 em diferentes locais de Punjab. Platyceps rhodorachis foi identificada com base na morfologia e confirmada por meio de sequências do gene COI. As sequências de DNA obtidas mostraram identificação de espécies confiável e exata. Sequências de DNA de Platyceps rhodorachis recém-produzidas foram submetidas ao GenBank e os números de acesso foram obtidos (MK936174.1, MK941839.1 e MT790210.1). Árvore N-J baseada em sequências COI de Platyceps rhodorachis claramente separadas como out-group com outros membros da família Colubridae com base na distância-p. A variação genética intraespecífica varia de 12% a 18%. As sequências de DNA de Platyceps rhodorachis kashmirensis, Platyceps rhodorachis ladacensis, Platyceps ventromaculatus, Platyceps ventromaculatus bengalensis e Platyceps ventromaculatus indusai não estão disponíveis no NCBI para validar suas posições taxonômicas. Em nossas recomendações, uma identificação de base molecular em grande escala da herpetofauna do Paquistão é necessária para relatar mais novas ou subespécies do país.(AU)
Assuntos
Animais , Serpentes/anatomia & histologia , Serpentes/genéticaRESUMO
Developmental pathways encompass transcription factors and cis-regulatory elements that interact as transcription factor-regulatory element (TF-RE) units. Independent origins of similar phenotypes likely involve changes in different parts of these units, a hypothesis promisingly tested addressing the evolution of the rib-associated lumbar (RAL) morphotype that characterizes emblematic animals such as snakes and elephants. Previous investigation in these lineages identified a polymorphism in the Homology region 1 [H1] enhancer of the Myogenic factor-5 [Myf5], which interacts with HOX10 proteins to modulate rib development. Here we address the evolution of TF-RE units focusing on independent origins of RAL morphotypes. We compiled an extensive database for H1-Myf5 and HOX10 sequences with two goals: (i) evaluate if the enhancer polymorphism is present in amphibians exhibiting the RAL morphotype and (ii) test a hypothesis of enhanced evolutionary flexibility mediated by TF-RE units, according to which independent origins of the RAL morphotype might involve changes in either component of the interaction unit. We identified the H1-Myf5 polymorphism in lineages that diverged around 340 Ma, including Lissamphibia. Independent origins of the RAL morphotype in Tetrapoda involved sequence variation in either component of the TF-RE unit, confirming that different changes may similarly affect the phenotypic outcome of a given developmental pathway.
Assuntos
Sequências Reguladoras de Ácido Nucleico , Fatores de Transcrição , Anfíbios/metabolismo , Animais , Fator Regulador Miogênico 5/genética , Fator Regulador Miogênico 5/metabolismo , Serpentes/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismoRESUMO
ABSTRACT: Developmental pathways encompass transcription factors and cis-regulatory elements that interact as transcription factor-regulatory element (TF-RE) units. Independent origins of similar phenotypes likely involve changes in different parts of these units, a hypothesis promisingly tested addressing the evolution of the rib-associated lumbar (RAL) morphotype that characterizes emblematic animals such as snakes and elephants. Previous investigation in these lineages identified a polymorphism in the Homology region 1 [H1] enhancer of the Myogenic factor-5 [Myf5], which interacts with HOX10 proteins to modulate rib development. Here we address the evolution of TF-RE units focusing on independent origins of RAL morphotypes. We compiled an extensive database for H1-Myf5 and HOX10 sequences with two goals: (i) evaluate if the enhancer polymorphism is present in amphibians exhibiting the RAL morphotype and (ii) test a hypothesis of enhanced evolutionary flexibility mediated by TF-RE units, according to which independent origins of the RAL morphotype might involve changes in either component of the interaction unit. We identified the H1-Myf5 polymorphism in lineages that diverged around 340 Ma, including Lissamphibia. Independent origins of the RAL morphotype in Tetrapoda involved sequence variation in either component of the TF-RE unit, confirming that different changes may similarly affect the phenotypic outcome of a given developmental pathway.
Assuntos
Animais , Serpentes/genética , Sequências Reguladoras de Ácido Nucleico , Fator Regulador Miogênico 5/genética , Fator Regulador Miogênico 5/metabolismo , Anfíbios/metabolismoRESUMO
Atractus badius has a long and controversial nomenclatural history due to both its antiquity and the brevity of its original description. This species was described based on two syntypes from Java. Later, a lectotype was designated and the distribution range restricted to the Guiana Shield. Although this species has been repeatedly recorded throughout Amazonia and the Andes, these records have been erroneously assigned to A. badius because of a considerable level of confusion in the literature. We found 13 additional specimens of this poorly known snake, expanding our knowledge on its morphological variability, phylogenetic relationships and distribution. In this paper, we report new localities and data on meristic, morphometric, coloration, scales micro-ornamentation, osteology and hemipenial morphology to A. badius. We also determine the phylogenetic position of A. badius as nested in a composite Guiana Shield clade. In addition, we discuss recent advances on the systematics of Atractus and comment on some 'new arrangements' with respect to previously recognized species groups and available morphological evidence. Finally, we highlight the importance of accurate voucher identification before promoting taxonomic changes or implementing nomenclatural acts derived from new phylogenetic hypotheses, and notably propose the synonymy of the recently described A. pyroni with A. roulei.
Assuntos
Genômica , Serpentes , Animais , Brasil , Osteologia , Filogenia , Serpentes/genéticaRESUMO
Garter snakes (Thamnophis) are a successful group of natricines endemic to North America. They have become important natural models for ecological and evolutionary research, yet prior efforts to resolve phylogenetic relationships have resulted in conflicting topologies and weak support for certain relationships. Here, we use genomic data generated with a reduced representation double-digest RADseq approach to reassess evolutionary relationships across Thamnophis. We then use the resulting phylogeny to better understand how biogeography and feeding ecology have influenced lineage diversification and morphological evolution. We recovered highly congruent and strongly supported topologies from maximum likelihood and Bayesian analyses, but some discordance with a multispecies coalescent approach. All phylogenomic estimates split Thamnophis into two clades largely defined by northern and southern North American species. Divergence time estimates and biogeographic analyses indicate a mid-Miocene origin of Thamnophis in Mexico. In addition, historic vicariant events thought to explain biogeographic patterns in other lineages (e.g., Isthmus of Tehuantepec, Rocky Mountain Range, and Trans-Mexican Volcanic Belt) appear to have influenced patterns of diversification in Thamnophis as well. Analyses of morphological traits associated with feeding ecology showed moderate to strong phylogenetic signal. Nevertheless, phylogenetic ANOVA suggested significant differences in certain cranial morphologies between aquatic specialists and garter snakes that are terrestrial-aquatic generalists, independent of evolutionary history. Our new estimate of Thamnophis phylogeny yields an improved understanding of the biogeographic history and morphological evolution of garter snakes, and provides a robust framework for future research on these snakes.
Assuntos
Colubridae , Animais , Teorema de Bayes , Colubridae/genética , México , América do Norte , Filogenia , Serpentes/genéticaRESUMO
Snakes are known to express a rod visual opsin and two cone opsins, only (SWS1, LWS), a reduced palette resulting from their supposedly fossorial origins. Dipsadid snakes in the genus Helicops are highly visual predators that successfully invaded freshwater habitats from ancestral terrestrial-only habitats. Here, we report the first case of multiple SWS1 visual pigments in a vertebrate, simultaneously expressed in different photoreceptors and conferring both UV and violet sensitivity to Helicops snakes. Molecular analysis and in vitro expression confirmed the presence of two functional SWS1 opsins, likely the result of recent gene duplication. Evolutionary analyses indicate that each sws1 variant has undergone different evolutionary paths with strong purifying selection acting on the UV-sensitive copy and dN/dS â¼1 on the violet-sensitive copy. Site-directed mutagenesis points to the functional role of a single amino acid substitution, Phe86Val, in the large spectral shift between UV and violet opsins. In addition, higher densities of photoreceptors and SWS1 cones in the ventral retina suggest improved acuity in the upper visual field possibly correlated with visually guided behaviors. The expanded visual opsin repertoire and specialized retinal architecture are likely to improve photon uptake in underwater and terrestrial environments, and provide the neural substrate for a gain in chromatic discrimination, potentially conferring unique color vision in the UV-violet range. Our findings highlight the innovative solutions undertaken by a highly specialized lineage to tackle the challenges imposed by the invasion of novel photic environments and the extraordinary diversity of evolutionary trajectories taken by visual opsin-based perception in vertebrates.
Assuntos
Visão de Cores , Opsinas , Animais , Água Doce , Opsinas/genética , Opsinas/metabolismo , Filogenia , Células Fotorreceptoras Retinianas Cones/metabolismo , Opsinas de Bastonetes/genética , Serpentes/genética , Serpentes/metabolismoRESUMO
Tetrapod taxa with broad geographic distributions across the Neotropics are often composed of multiple evolutionary lineages. In this paper, we present the most complete phylogeny of Leptophis to date and assess morphology-based species limits within the broadly distributed green parrot snake Leptophis ahaetulla sensu lato, which occurs from Mexico to Argentina. Although L. ahaetulla sensu stricto, L. nigromarginatus and L. occidentalis were recovered as paraphyletic, tree topology tests failed to reject their monophyly. Monophyly of L. bocourti, L. coeruleodorsus, L. cupreus, L. depressirostris, L. marginatus, L. riveti and L. sp. nov. was strongly supported. Our phylogenetic trees support recognition of multiple species within Leptophis ahaetulla sensu lato and suggest that color evolution and the uplift of the Andes played an important role in the diversification of parrot snakes.
Assuntos
Colubridae , Papagaios , Animais , Argentina , Colubridae/genética , México , Filogenia , Serpentes/genéticaRESUMO
MOTIVATION: Next-generation sequencing has become exceedingly common and has transformed our ability to explore nonmodel systems. In particular, transcriptomics has facilitated the study of venom and evolution of toxins in venomous lineages; however, many challenges remain. Primarily, annotation of toxins in the transcriptome is a laborious and time-consuming task. Current annotation software often fails to predict the correct coding sequence and overestimates the number of toxins present in the transcriptome. Here, we present ToxCodAn, a python script designed to perform precise annotation of snake venom gland transcriptomes. We test ToxCodAn with a set of previously curated transcriptomes and compare the results to other annotators. In addition, we provide a guide for venom gland transcriptomics to facilitate future research and use Bothrops alternatus as a case study for ToxCodAn and our guide. RESULTS: Our analysis reveals that ToxCodAn provides precise annotation of toxins present in the transcriptome of venom glands of snakes. Comparison with other annotators demonstrates that ToxCodAn has better performance with regard to run time ($>20x$ faster), coding sequence prediction ($>3x$ more accurate) and the number of toxins predicted (generating $>4x$ less false positives). In this sense, ToxCodAn is a valuable resource for toxin annotation. The ToxCodAn framework can be expanded in the future to work with other venomous lineages and detect novel toxins.
Assuntos
Algoritmos , Biologia Computacional/métodos , Perfilação da Expressão Gênica/métodos , Venenos de Serpentes/genética , Serpentes/genética , Toxinas Biológicas/genética , Animais , Sequenciamento de Nucleotídeos em Larga Escala/métodos , Filogenia , Venenos de Serpentes/química , Venenos de Serpentes/metabolismo , Serpentes/classificação , Serpentes/metabolismo , Especificidade da Espécie , Toxinas Biológicas/química , Toxinas Biológicas/metabolismoRESUMO
The Boidae family is an ancient group of snakes widely distributed across the Neotropical region, where several biogeographic events contributed towards shaping their evolution and diversification. Most species of this family have a diploid number composed of 2n = 36; however, among Booidea families, the Boidae stands out by presenting the greatest chromosomal diversity, with 2n ranging between 36 and 44 chromosomes and an undifferentiated XY sex chromosome system. Here, we applied a comparative chromosome analysis using cross-species chromosome paintings in five species representing four Boidae genera, to decipher the evolutionary dynamics of some chromosomes in these Neotropical snakes. Our study included all diploid numbers (2n = 36, 40, and 44) known for this family and our comparative chromosomal mappings point to a strong evolutionary relationship among the genera Boa, Corallus, Eunectes, and Epicrates. The results also allowed us to propose the cytogenomic diversification that had occurred in this family: a process mediated by centric fissions, including fission events of the putative and undifferentiated XY sex chromosome system in the 2n = 44 karyotype, which is critical in solving the puzzle of the karyotype evolution of boid snakes.