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2.
Nature ; 622(7982): 308-314, 2023 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-37794184

RESUMEN

Systematic assessments of species extinction risk at regular intervals are necessary for informing conservation action1,2. Ongoing developments in taxonomy, threatening processes and research further underscore the need for reassessment3,4. Here we report the findings of the second Global Amphibian Assessment, evaluating 8,011 species for the International Union for Conservation of Nature Red List of Threatened Species. We find that amphibians are the most threatened vertebrate class (40.7% of species are globally threatened). The updated Red List Index shows that the status of amphibians is deteriorating globally, particularly for salamanders and in the Neotropics. Disease and habitat loss drove 91% of status deteriorations between 1980 and 2004. Ongoing and projected climate change effects are now of increasing concern, driving 39% of status deteriorations since 2004, followed by habitat loss (37%). Although signs of species recoveries incentivize immediate conservation action, scaled-up investment is urgently needed to reverse the current trends.


Asunto(s)
Anfibios , Cambio Climático , Ecosistema , Especies en Peligro de Extinción , Animales , Anfibios/clasificación , Biodiversidad , Cambio Climático/estadística & datos numéricos , Conservación de los Recursos Naturales/economía , Conservación de los Recursos Naturales/tendencias , Especies en Peligro de Extinción/estadística & datos numéricos , Especies en Peligro de Extinción/tendencias , Extinción Biológica , Riesgo , Urodelos/clasificación
3.
Nature ; 605(7909): 285-290, 2022 05.
Artículo en Inglés | MEDLINE | ID: mdl-35477765

RESUMEN

Comprehensive assessments of species' extinction risks have documented the extinction crisis1 and underpinned strategies for reducing those risks2. Global assessments reveal that, among tetrapods, 40.7% of amphibians, 25.4% of mammals and 13.6% of birds are threatened with extinction3. Because global assessments have been lacking, reptiles have been omitted from conservation-prioritization analyses that encompass other tetrapods4-7. Reptiles are unusually diverse in arid regions, suggesting that they may have different conservation needs6. Here we provide a comprehensive extinction-risk assessment of reptiles and show that at least 1,829 out of 10,196 species (21.1%) are threatened-confirming a previous extrapolation8 and representing 15.6 billion years of phylogenetic diversity. Reptiles are threatened by the same major factors that threaten other tetrapods-agriculture, logging, urban development and invasive species-although the threat posed by climate change remains uncertain. Reptiles inhabiting forests, where these threats are strongest, are more threatened than those in arid habitats, contrary to our prediction. Birds, mammals and amphibians are unexpectedly good surrogates for the conservation of reptiles, although threatened reptiles with the smallest ranges tend to be isolated from other threatened tetrapods. Although some reptiles-including most species of crocodiles and turtles-require urgent, targeted action to prevent extinctions, efforts to protect other tetrapods, such as habitat preservation and control of trade and invasive species, will probably also benefit many reptiles.


Asunto(s)
Conservación de los Recursos Naturales , Extinción Biológica , Reptiles , Caimanes y Cocodrilos , Anfibios , Animales , Biodiversidad , Aves , Mamíferos , Filogenia , Reptiles/clasificación , Medición de Riesgo , Tortugas
4.
PeerJ ; 8: e9411, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-32685285

RESUMEN

Frogs of the genus Microhyla include some of the world's smallest amphibians and represent the largest radiation of Asian microhylids, currently encompassing 50 species, distributed across the Oriental biogeographic region. The genus Microhyla remains one of the taxonomically most challenging groups of Asian frogs and was found to be paraphyletic with respect to large-sized fossorial Glyphoglossus. In this study we present a time-calibrated phylogeny for frogs in the genus Microhyla, and discuss taxonomy, historical biogeography, and morphological evolution of these frogs. Our updated phylogeny of the genus with nearly complete taxon sampling includes 48 nominal Microhyla species and several undescribed candidate species. Phylogenetic analyses of 3,207 bp of combined mtDNA and nuDNA data recovered three well-supported groups: the Glyphoglossus clade, Southeast Asian Microhyla II clade (includes M. annectens species group), and a diverse Microhyla I clade including all other species. Within the largest major clade of Microhyla are seven well-supported subclades that we identify as the M. achatina, M. fissipes, M. berdmorei, M. superciliaris, M. ornata, M. butleri, and M. palmipes species groups. The phylogenetic position of 12 poorly known Microhyla species is clarified for the first time. These phylogenetic results, along with molecular clock and ancestral area analyses, show the Microhyla-Glyphoglossus assemblage to have originated in Southeast Asia in the middle Eocene just after the first hypothesized land connections between the Indian Plate and the Asian mainland. While Glyphoglossus and Microhyla II remained within their ancestral ranges, Microhyla I expanded its distribution generally east to west, colonizing and diversifying through the Cenozoic. The Indian Subcontinent was colonized by members of five Microhyla species groups independently, starting with the end Oligocene-early Miocene that coincides with an onset of seasonally dry climates in South Asia. Body size evolution modeling suggests that four groups of Microhyla have independently achieved extreme miniaturization with adult body size below 15 mm. Three of the five smallest Microhyla species are obligate phytotelm-breeders and we argue that their peculiar reproductive biology may be a factor involved in miniaturization. Body size increases in Microhyla-Glyphoglossus seem to be associated with a burrowing adaptation to seasonally dry habitats. Species delimitation analyses suggest a vast underestimation of species richness and diversity in Microhyla and reveal 15-33 undescribed species. We revalidate M. nepenthicola, synonymize M. pulverata with M. marmorata, and provide insights on taxonomic statuses of a number of poorly known species. Further integrative studies, combining evidence from phylogeny, morphology, advertisement calls, and behavior will result in a better systematic understanding of this morphologically cryptic radiation of Asian frogs.

5.
Zootaxa ; 4545(3): 389-407, 2019 Jan 17.
Artículo en Inglés | MEDLINE | ID: mdl-30790907

RESUMEN

A new species of Cnemaspis Strauch, 1887 is described from Nilgala Savannah Forest in Sri Lanka. The new species is diagnosed from all other congeners by the following suite of characters: small body size (SVL< 33 mm), dorsal scales on trunk homogeneous, one pair of post mentals separated by a single small chin scale, ventral scales on trunk smooth, subimbricate, 17-19 scales across the belly. Subdigitals scansors smooth, entire, unnotched; lamellae under digit IV of pes 17 -18. Males with femoral pores on each thigh but lacking precloacal pores. Median row of subcaudals smooth, subimbricate, enlarged and in an irregular series of subhexagonal scales. This new species had been previously confused with Cnemaspis alwisi Wickramasinghe Munidradasa, 2007. The new species differs from Cnemaspis alwisi by having 122-129 ventral scales (versus 146-152), 7-8 supralabials (versus 8-10), and relatively shorter SVL ranging between 31.5-32.9 mm (versus 37.8-39.9 mm). Further, the new species is genetically divergent from Cnemaspis alwisi, the species that it closely resembles by 13.5% and 7.8% from its sister species in the ND2 gene. The present discovery highlights the need for dedicated herpetofaunal explorations in Sri Lanka, especially the intermediate bioclimatic zone and associated cave systems and rock outcrops.


Asunto(s)
Lagartos , Distribución Animal , Estructuras Animales , Animales , Tamaño Corporal , Cuevas , Bosques , Masculino , Sri Lanka
6.
Toxicon X ; 4: 100015, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-32550572

RESUMEN

The Ceylon krait (Bungarus ceylonicus) is a highly venomous elapid snake endemic to Sri Lanka. Its bites are rare and only seven reports are found in the literature. Therefore, the clinical manifestations and natural history of envenoming of Ceylon krait are not well studied yet. Neuroparalysis is the main clinical manifestation of their bites. We report two cases of proven Ceylon krait bites of two young snake keepers working in a serpentarium. They developed acute neuroparalysis, abdominal pain and a period of amnesia. The first patient developed myalgia and increased level of serum creatine kinase suggestive of rhabdomyolysis. One was treated with Indian polyvalent antivenom and both recovered with some long-lasting clinical disabilities namely impairment of sensation of the bitten arm and persistent refraction errors in the eyes in the first patient. The second patient had persistent marked nystagmus.

8.
Ecol Evol ; 8(20): 10219-10232, 2018 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-30397460

RESUMEN

A large body of evidence indicates that evolutionary innovations of novel organs have facilitated the subsequent diversification of species. Investigation of the evolutionary history of such organs should provide important clues for understanding the basis for species diversification. An Asian natricine snake, Rhabdophis tigrinus, possesses a series of unusual organs, called nuchal glands, which contain cardiotonic steroid toxins known as bufadienolides. Rhabdophis tigrinus sequesters bufadienolides from its toad prey and stores them in the nuchal glands as a defensive mechanism. Among more than 3,500 species of snakes, only 17 Asian natricine species are known to possess nuchal glands or their homologues. These 17 species belong to three nominal genera, Balanophis, Macropisthodon, and Rhabdophis. In Macropisthodon and Rhabdophis, however, species without nuchal glands also exist. To infer the evolutionary history of the nuchal glands, we investigated the molecular phylogenetic relationships among Asian natricine species with and without nuchal glands, based on variations in partial sequences of Mt-CYB, Cmos, and RAG1 (total 2,767 bp). Results show that all species with nuchal glands belong to a single clade (NGC). Therefore, we infer that the common ancestor of this clade possessed nuchal glands with no independent origins of the glands within the members. Our results also imply that some species have secondarily lost the glands. Given the estimated divergence time of related species, the ancestor of the nuchal gland clade emerged 19.18 mya. Our study shows that nuchal glands are fruitful subjects for exploring the evolution of novel organs. In addition, our analysis indicates that reevaluation of the taxonomic status of the genera Balanophis and Macropisthodon is required. We propose to assign all species belonging to the NGC to the genus Rhabdophis, pending further study.

9.
Zootaxa ; 3964(1): 146-8, 2015 May 29.
Artículo en Inglés | MEDLINE | ID: mdl-26249428

RESUMEN

The first study on ticks on reptiles of Sri Lanka dates back to Seneviratna (1965) who reported ticks from five reptiles. Later studies were either limited to one reptile (Fernando & Fernando 2012), or captive animals in zoos (Fernando & Randeniaya 2009) and household pets (Nathanael et al. 2004). According to the current classification (Guglielmone et al. 2010), all the tick species previously recorded on reptiles belong to five species of Amblyomma: A. clypeolatum Neumann, A. gervaisi (Lucas), A. pattoni (Neumann), A. trimaculatum (Lucas) and A. varanense (Supino). Some of the species listed by Seneviratna (1965) were either synonyms or invalid in respect to the present classification. For example Amblyomma laeve sensu Warburton (1910) is a junior synonym of A. pattoni and A. gervaisii var. lucasi is considered a junior synonym of A. varanense (Guglielmone et al. 2010; D. Apanaskevich pers. comm.).


Asunto(s)
Reptiles/parasitología , Infestaciones por Garrapatas/veterinaria , Garrapatas/clasificación , Estructuras Animales/anatomía & histología , Estructuras Animales/crecimiento & desarrollo , Animales , Tamaño Corporal , Femenino , Especificidad del Huésped , Masculino , Tamaño de los Órganos , Reptiles/clasificación , Sri Lanka , Infestaciones por Garrapatas/parasitología , Garrapatas/anatomía & histología , Garrapatas/crecimiento & desarrollo , Garrapatas/fisiología
10.
Mol Ecol ; 22(10): 2742-59, 2013 May.
Artículo en Inglés | MEDLINE | ID: mdl-23506038

RESUMEN

The viviparous sea snakes (Hydrophiinae) are a young radiation of at least 62 species that display spectacular morphological diversity and high levels of local sympatry. To shed light on the mechanisms underlying sea snake diversification, we investigated recent speciation and eco-morphological differentiation in a clade of four nominal species with overlapping ranges in Southeast Asia and Australia. Analyses of morphology and stomach contents identified the presence of two distinct ecomorphs: a 'macrocephalic' ecomorph that reaches >2 m in length, has a large head and feeds on crevice-dwelling eels and gobies; and a 'microcephalic' ecomorph that rarely exceeds 1 m in length, has a small head and narrow fore-body and hunts snake eels in burrows. Mitochondrial sequences show a lack of reciprocal monophyly between ecomorphs and among putative species. However, individual assignment based on newly developed microsatellites separated co-distributed specimens into four significantly differentiated clusters corresponding to morphological species designations, indicating limited recent gene flow and progress towards speciation. A coalescent species tree (based on mitochondrial and nuclear sequences) and isolation-migration model (mitochondrial and microsatellite markers) suggest between one and three transitions between ecomorphs within the last approximately 1.2 million to approximately 840,000 years. In particular, the macrocephalic 'eastern' population of Hydrophis cyanocinctus and microcephalic H. melanocephalus appear to have diverged very recently and rapidly, resulting in major phenotypic differences and restriction of gene flow in sympatry. These results highlight the viviparous sea snakes as a promising system for speciation studies in the marine environment.


Asunto(s)
Elapidae/anatomía & histología , Elapidae/genética , Especiación Genética , Cabeza/anatomía & histología , Fenotipo , Filogenia , Animales , Asia Sudoriental , Australia , Secuencia de Bases , Teorema de Bayes , Cartilla de ADN/genética , ADN Mitocondrial/genética , Elapidae/fisiología , Conducta Alimentaria/fisiología , Contenido Digestivo/química , Flujo Génico/genética , Genética de Población , Repeticiones de Microsatélite/genética , Modelos Genéticos , Datos de Secuencia Molecular , Análisis de Secuencia de ADN , Especificidad de la Especie
11.
Mol Phylogenet Evol ; 66(1): 262-9, 2013 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-23044399

RESUMEN

We present a striking case of phenotypic convergence within the speciose and taxonomically unstable Hydrophis group of viviparous sea snakes. Enhydrina schistosa, the 'beaked sea snake', is abundant in coastal and inshore habitats throughout the Asian and Australian regions, where it is responsible for the large majority of recorded deaths and injuries from sea snake bites. Analyses of five independent mitochondrial and nuclear loci for populations spanning Australia, Indonesia and Sri Lanka indicate that this 'species' actually consists of two distinct lineages in Asia and Australia that are not closest relatives. As a result, Australian "E. schistosa" are elevated to species status and provisionally referred to Enhydrinazweifeli. Convergence in the characteristic 'beaked' morphology of these species is probably associated with the wide gape required to accommodate their spiny prey. Our findings have important implications for snake bite management in light of the medical importance of beaked sea snakes and the fact that the only sea snake anti-venom available is raised against Malaysian E. schistosa.


Asunto(s)
Elapidae/genética , Especiación Genética , Filogenia , Animales , Australia , Teorema de Bayes , Núcleo Celular/genética , ADN Mitocondrial/genética , Elapidae/anatomía & histología , Elapidae/clasificación , Indonesia , Funciones de Verosimilitud , Modelos Genéticos , Fenotipo , Análisis de Secuencia de ADN , Sri Lanka
12.
Mol Phylogenet Evol ; 57(1): 343-52, 2010 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-20601010

RESUMEN

Hemidactylus geckos are a species-rich component of many tropical lizard assemblages. We sampled deeply among tropical Asian, and especially South Asian, taxa and used a multi-gene approach to establish the affinities of Indian and Sri Lankan Hemidactylus and to evaluate the monophyly of previously proposed taxa within the genus. There is only weak support for the monophyly of tropical Asian Hemidactylus as a whole, but two strongly supported subclades were retrieved: the bowringii group is a predominantly East Asian clade that reaches South Asia only peripherally; the brookii group is a morphologically diverse clade that represents a previously unrecognized, species-rich (25 species), chiefly South Asian radiation. Deep genetic divergences support the specific recognition of three Sri Lankan taxa previously regarded as subspecies of mainland forms and validate H. subtriedrus as a species distinct from H. triedrus. Unlike several other vertebrate groups, Sri Lankan Hemidactylus do not represent a single insular radiation. Rather, each of six Sri Lankan species reached the island independently from different continental sources. There have been extensive Quaternary land connections between India and Sri Lanka but sister-species pairs of Hemidactylus on the two land masses diverged from one another much earlier, probably in the mid-Miocene.


Asunto(s)
Evolución Molecular , Lagartos/genética , Filogenia , Animales , Asia , Lagartos/clasificación , Análisis de Secuencia de ADN , Sri Lanka
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