80 research outputs found
Jurassic frogs and the evolution of amphibian endemism in the Western Ghats
The diversity of frogs and toads (Anurans) in tropical
evergreen forests has recently gained importance with
reports of several new species1. We describe here a
fossorial frog taxon related to the African Heleophrynidae and Seychellian Sooglossidae from the Western Ghats of India. This frog possesses a suite of
unique ancient characters indicating that it is a transitional form between Archaeobatrachians and Neobatrachians. Molecular clock analysis based on the
nucleotide diversity in mitochondrial 12S and 16S genes dates this frog as a Gondwana relic, which evolved 150â195 Mya during the mid-Jurassic period.With this taxon, the evolution of endemism in the Western Ghats and other Gondwana break up landmasses is now dated much before the CretaceousâTertiary boundary. We propose that sea level surges in the late Jurassic2 isolated tablelands creating insular amphibian fauna. Reduction in area may have promoted stochastic extinctions and resulted in amphibian endemism. Our study reinforces the conservation significance of the Western Ghats as major global hotspot of biodiversity. The habitat of this endemic amphibian
lineage is currently endangered due to various upcoming
dam projects, which is a cause of serious conservation
concern
Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences
The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & NemĂ©sio 2007; Donegan 2008, 2009; NemĂ©sio 2009aâb; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported
by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on
18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based
researchers who signed it in the short time span from 20 September to 6 October 2016
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Averting biodiversity collapse in tropical forest protected areas
The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenonÂčâ»Âł. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stressesâŽâ»âč. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the worldâs major tropical regions. Our analysis reveals great variation in reserve âhealthâ: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.Keywords: Ecology, Environmental scienc
Impact of Dams on Riparian Frog Communities in the Southern Western Ghats, India
The Western Ghats is a global biodiversity hotspot and home to diverse and unique assemblages of amphibians. Several rivers originate from these mountains and hydropower is being tapped from them. The impacts of hydrological regulation of riparian ecosystems to wildlife and its habitat are poorly documented, and in particular the fate of frog populations is unknown. We examined the effects of dams on riparian frog communities in the Thamirabarani catchment in southern Western Ghats. We used nocturnal visual encounter surveys constrained for time, to document the species richness of frogs below and above the dam, and also at control sites in the same catchment. While we did not find differences in species richness below and above the dams, the frog community composition was significantly altered as a likely consequence of altered flow regime. The frog species compositions in control sites were similar to above-dam sites. Below-dam sites had a distinctly different species composition. Select endemic frog species appeared to be adversely impacted due to the dams. Below-dam sites had a greater proportion of generalist and widely distributed species. Dams in the Western Ghats appeared to adversely impact population of endemic species, particularly those belonging to the genus Nyctibatrachus that shows specialization for intact streams
Evaluating Antivenom Efficacy against Echis carinatus Venoms—Screening for In Vitro Alternatives
In India, polyvalent antivenom is the mainstay treatment for snakebite envenoming. Due to batch-to-batch variation in antivenom production, manufacturers have to estimate its efficacy at each stage of IgG purification using the median effective dose which involves 100–120 mice for each batch. There is an urgent need to replace the excessive use of animals in snake antivenom production using in vitro alternatives. We tested the efficacy of a single batch of polyvalent antivenom from VINS bioproducts limited on Echis carinatus venom collected from three different locations—Tamil Nadu (ECVTN), Goa (ECVGO) and Rajasthan (ECVRAJ)—using different in vitro assays. Firstly, size-exclusion chromatography (SEC-HPLC) was used to quantify antivenom–venom complexes to assess the binding efficiency of the antivenom. Secondly, clotting, proteolytic and PLA2 activity assays were performed to quantify the ability of the antivenom to neutralize venom effects. The use of both binding and functional assays allowed us to measure the efficacy of the antivenom, as they represent multiple impacts of snake envenomation. The response from the assays was recorded for different antivenom–venom ratios and the dose–response curves were plotted. Based on the parameters that explained the curves, the efficacy scores (ES) of antivenom were computed. The binding assay revealed that ECVTN had more antivenom–venom complexes formed compared to the other venoms. The capacity of antivenom to neutralize proteolytic and PLA2 effects was lowest against ECVRAJ. The mean efficacy score of antivenom against ECVTN was the greatest, which was expected, as ECVTN is mainly used by antivenom manufacturers. These findings pave a way for the development of in vitro alternatives in antivenom efficacy assessment
Andaman frog data
Data from Andaman islands on abundances of frogs from the forest floor. Sampling was done using 10 x 10 m quadrats that were open (not fenced) and bounded (that were fenced)
Surfactant effects on methanol oxidation at PtâRu/C coated glassy carbon electrode
The role of surfactants, cetyl trimethyl ammonium
bromide (CTAB), sodium dodecyl sulphate (SDS) and
Triton X-100 (in the catalyst), on methanol oxidation at
commercial 50:50 PtâRu/C catalyst-coated glassy carbon
has been studied using cyclic voltammetry, scanning
electron microscopy (SEM) and Fourier transform infrared
spectroscopy (FT-IR). Surfactant containing catalysts
showed a considerable reduction in the methanol oxidation
potential. In terms of oxidation potential, better results
(lower methanol oxidation potential) were observed in the
order SDS>Triton X-100>CTAB>no surfactant. SEM
studies on the catalyst ink showed better homogeneity in
the sample prepared using surfactant. This indicates better
Pt Pt contact, which is likely to favour methanol adsorption
and its oxidation. Hence, lowering of oxidation potentials
for methanol oxidation could be seen with use of
surfactants. Results of FT-IR on the catalyst ink showed
definite changes in the frequencies in the case of PtâRu/C
containing surfactants indicating definite interaction between
catalyst and surfactant. Catalysts, with and without
surfactants, yielded linear plots of concentration vs peak
currents for methanol oxidation (0â2 M). With surfactant
containing catalysts, reduction in methanol oxidation
current was observed, and the order followed was the
reverse of the above
Key to Andaman lizard and frog data
Data on the islands that were sampled during the stud
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