ORCID Profile
0000-0003-3389-6416
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Publisher: Magnolia Press
Date: 21-12-2016
DOI: 10.11646/ZOOTAXA.4208.6.3
Abstract: Microhyla sholigari is an endangered frog described in the year 2000. The original description was based on non-adult types and lacked information on several morphological characters, call structure, genetic material and photographs of the animal in life. The absence of such information posed challenges in field identification of this species. Since the original description, there is one other reported sighting of this species from Kerala in 2001. We encountered specimens that we confer to this species based on morphological similarity to the subadult holotype, from several new localities within and outside the Western Ghats of Karnataka. We here redescribe the species based on additional adult vouchers, provide molecular data, describe the advertisement call and report a range extension. Based on its current distribution, we assess the threat status of the species and suggest listing it as Least Concern according to IUCN Red List criteria. Our paper bridges an important gap in the knowledge of the genus Microhyla in India and highlights the importance of systematic surveys in documenting and understanding hibian ersity in the region.
Publisher: Wiley
Date: 19-02-2020
Abstract: Noninvasive s ling methods for studying intestinal microbiomes are widely applied in studies of endangered species and in those conducting temporal monitoring during manipulative experiments. Although existing studies show that noninvasive s ling methods among different taxa vary in their accuracy, no studies have yet been published comparing nonlethal s ling methods in adult hibians. In this study, we compare microbiomes from two noninvasive s le types (faeces and cloacal swabs) to that of the large intestine in adult cane toads, Rhinella marina. We use 16S rRNA gene sequencing to investigate how microbial communities change along the digestive tract and which nonlethal s ling method better represents large intestinal microbiota. We found that cane toads' intestinal microbiota was dominated by Bacteroidetes, Proteobacteria and Firmicutes and, interestingly, we also saw a high proportion of Fusobacteria, which has previously been associated with marine species and changes in frog immunity. The large and small intestine of cane toads had a similar microbial composition, but the large intestine showed higher ersity. Our results indicate that cloacal swabs were more similar to large intestine s les than were faecal s les, and small intestine s les were significantly different from both nonlethal s le types. Our study provides valuable information for future investigations of the cane toad gut microbiome and validates the use of cloacal swabs as a nonlethal method to study changes in the large intestine microbiome. These data provide insights for future studies requiring nonlethal s ling of hibian gut microbiota.
Publisher: Cold Spring Harbor Laboratory
Date: 26-10-2023
Publisher: The Royal Society
Date: 19-04-2021
Abstract: In response to novel environments, invasive populations often evolve rapidly. Standing genetic variation is an important predictor of evolutionary response but epigenetic variation may also play a role. Here, we use an iconic invader, the cane toad ( Rhinella marina ), to investigate how manipulating epigenetic status affects phenotypic traits. We collected wild toads from across Australia, bred them, and experimentally manipulated DNA methylation of the subsequent two generations (G1, G2) through exposure to the DNA methylation inhibitor zebularine and/or conspecific tadpole alarm cues. Direct exposure to alarm cues (an indicator of predation risk) increased the potency of G2 tadpole chemical cues, but this was accompanied by reductions in survival. Exposure to alarm cues during G1 also increased the potency of G2 tadpole cues, indicating intergenerational plasticity in this inducible defence. In addition, the negative effects of alarm cues on tadpole viability (i.e. the costs of producing the inducible defence) were minimized in the second generation. Exposure to zebularine during G1 induced similar intergenerational effects, suggesting a role for alteration in DNA methylation. Accordingly, we identified intergenerational shifts in DNA methylation at some loci in response to alarm cue exposure. Substantial demethylation occurred within the sodium channel epithelial 1 subunit gamma gene ( SCNN1G ) in alarm cue exposed in iduals and their offspring. This gene is a key to the regulation of sodium in epithelial cells and may help to maintain the protective epidermal barrier. These data suggest that early life experiences of tadpoles induce intergenerational effects through epigenetic mechanisms, which enhance larval fitness. This article is part of the theme issue ‘How does epigenetics influence the course of evolution?’
Publisher: Oxford University Press (OUP)
Date: 16-06-2020
DOI: 10.1093/ICB/ICAA082
Abstract: The developmental environment can exert powerful effects on animal phenotype. Recently, epigenetic modifications have emerged as one mechanism that can modulate developmentally plastic responses to environmental variability. For ex le, the DNA methylation profile at promoters of hormone receptor genes can affect their expression and patterns of hormone release. Across taxonomic groups, epigenetic alterations have been linked to changes in glucocorticoid (GC) physiology. GCs are metabolic hormones that influence growth, development, transitions between life-history stages, and thus fitness. To date, relatively few studies have examined epigenetic effects on phenotypic traits in wild animals, especially in hibians. Here, we examined the effects of exposure to predation threat (alarm cues) and experimentally manipulated DNA methylation on corticosterone (CORT) levels in tadpoles and metamorphs of the invasive cane toad (Rhinella marina). We included offspring of toads s led from populations across the species’ Australian range. In these animals, exposure to chemical cues from injured conspecifics induces shifts in developmental trajectories, putatively as an adaptive response that lessens vulnerability to predation. We exposed tadpoles to these alarm cues, and measured changes in DNA methylation and CORT levels, both of which are mechanisms that have been implicated in the control of phenotypically plastic responses in tadpoles. To test the idea that DNA methylation drives shifts in GC physiology, we also experimentally manipulated methylation levels with the drug zebularine. We found differentially methylated regions (DMRs) between control tadpoles and their full-siblings exposed to alarm cues, zebularine, or both treatments. However, the effects of these manipulations on methylation patterns were weaker than clutch (e.g., genetic, maternal, etc.) effects. CORT levels were higher in larval cane toads exposed to alarm cues and zebularine. We found little evidence of changes in DNA methylation across the GC receptor gene (NR3C1) promoter region in response to alarm cue or zebularine exposure. In both alarm cue and zebularine-exposed in iduals, we found differentially methylated DNA in the suppressor of cytokine signaling 3 gene (SOCS3), which may be involved in predator avoidance behavior. In total, our data reveal that alarm cues have significant impacts on tadpole physiology, but show only weak links between DNA methylation and CORT levels. We also identify genes containing DMRs in tadpoles exposed to alarm cues and zebularine, particularly in range-edge populations, that warrant further investigation.
Publisher: Public Library of Science (PLoS)
Date: 30-11-2015
Publisher: Public Library of Science (PLoS)
Date: 02-03-2016
Location: India
No related grants have been discovered for Roshmi Rekha Sarma.