The Experts below are selected from a list of 243 Experts worldwide ranked by ideXlab platform

John Measey - One of the best experts on this subject based on the ideXlab platform.

  • Non-native populations and global invasion potential of the Indian bullfrog Hoplobatrachus tigerinus: a synthesis for risk-analysis
    Biological Invasions, 2020
    Co-Authors: Nitya Prakash Mohanty, Angelica Crottini, Raquel A. Garcia, John Measey
    Abstract:

    Invasive amphibians have considerable ecological and socio-economic impact. However, strong taxonomic biases in the existing literature necessitate synthesizing knowledge on emerging invaders. The Indian bullfrog, Hoplobatrachus tigerinus , a large dicroglossid frog (snout to vent length: up to 160 mm), is native to the Indian sub-continent. Despite the high likelihood of invasion success for H. tigerinus , based on the species’ natural history traits and human use, the status of its non-native populations and global invasion potential has not yet been assessed. In this paper, we provide a profile of H. tigerinus as an invasive species to aid in risk analyses and management of existing populations. We review the available knowledge on non-native populations of H. tigerinus and model its potential distribution in the non-native range and globally; finally, we evaluate its ecological and socio-economic impact using standard impact classification schemes. We confirm successful invasions on the Andaman archipelago and Madagascar. The ensemble species distribution model, with ‘good’ predictive ability and transferability, predicts tropical regions of the world to be climatically suitable for the species. Considering potential for propagule pressure, we predict the climatically suitable Mascarene Islands, Malaysia and Indonesia, and East Africa to likely be recipients of bridgehead invasions. We assign the species two impact scores: both socio-economic and environmental scores were ‘moderate’ with ‘medium’ confidence levels in our assessment. Finally, this synthesis outlines the invasion process of the genus Hoplobatrachus , which is an emerging group of amphibian invaders.

  • No survival of native larval frogs in the presence of invasive Indian bullfrog Hoplobatrachus tigerinus tadpoles
    Biological Invasions, 2019
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Invasive amphibians have considerable negative impacts on recipient ecosystems, however, impact has been assessed for only a few species, limiting risk assessments. In particular, the impact of invasive anurans with carnivorous tadpoles have not been examined thoroughly. The Indian bullfrog ( Hoplobatrachus tigerinus ), native to the Indian sub-continent, is rapidly invading the Andaman archipelago, Bay of Bengal after its recent introduction. We aimed to evaluate the effect of carnivorous H. tigerinus tadpoles on two species of endemic anuran tadpoles Microhyla chakrapanii and Kaloula ghoshi , in a mesocosm experiment. Rapid predation by larval H. tigerinus resulted in no survival of endemic frog tadpoles. Survival of H. tigerinus was density-dependent. The study is timely in elucidating the impact of invasive larval H. tigerinus on native anurans and substantiates the need to manage invasive populations (or potential incursions) of the species on the Andaman archipelago and elsewhere.

  • What's for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago.
    PeerJ, 2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    CITATION: Mohanty, N. P. & Measey, J. 2018. What's for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago. PeerJ, 6:e5698, doi:10.7717/peerj.5698.

  • What’s for dinner? Diet and trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago
    2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Amphibian invasions have considerable detrimental impacts on recipient ecosystems; however, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We assessed the diet of the invasive Hoplobatrachus tigerinus (n = 358), the native Limnonectes spp. (n = 375) and Fejervarya spp. (n = 65) in three sites, across four habitat types and two seasons, on the Andaman archipelago. We found a significant dietary overlap of H. tigerinus with Limnonectes spp., which may lead to competition. Small vertebrates, including several endemic species, constituted a majority of H. tigerinus diet by volume, suggesting potential impact by predation. Diets of the three species were mostly governed by the positive relationship between predator-prey body sizes. Niche breadth analyses did not indicate any significant changes in diet between seasons. Hoplobatrachus tigerinus and Fejervarya spp. chose evasive prey, suggesting that these two species are mostly ambush predators; Limnonectes spp. elected sedentary prey; although a large portion of its diet consisted of other prey types, such electivity indicates ‘active search’ as its major foraging strategy. All three species of anurans mostly consumed terrestrial prey. This intensive study on a new genus of invasive amphibian contributes to the knowledge on impacts of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We stress on the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians.

  • What’s for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago
    PeerJ Inc., 2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Amphibian invasions have considerable detrimental impacts on recipient ecosystems. However, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We carried out diet analyses of the invasive H. tigerinus and native anurans, across four habitat types and two seasons; we hypothesized that (i) small vertebrates constitute a majority of the H. tigerinus diet, particularly by volume and (ii) the diet of H. tigerinus significantly overlaps with the diet of native anurans, thereby, leading to potential competition. We assessed the diet of the invasive H. tigerinus (n = 358), and individuals of the genera Limnonectes (n = 375) and Fejervarya (n = 65) and found a significant dietary overlap of H. tigerinus with only Limnonectes. Small vertebrates, including several endemic species, constituted the majority of H. tigerinus, diet by volume, suggesting potential impact by predation. Prey consumption and electivity of the three anurans indicated a positive relationship between predator-prey body sizes. Individuals of H. tigerinus and Fejervarya chose evasive prey, suggesting that these two taxa are mostly ambush predators; individuals of Limnonectes chose a mixture of sedentary and evasive prey indicating that the species employs a combination of ‘active search’ and ‘sit and wait’ foraging strategies. All three species of anurans mostly consumed terrestrial prey. This intensive study on a genus of newly invasive amphibian contributes to knowledge of the impact of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We also stress the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians

Srinivas K. Saidapur - One of the best experts on this subject based on the ideXlab platform.

  • Behavioral responses of tadpoles of Duttaphrynus melanostictus (Anura: Bufonidae) to cues of starved and fed dragonfly larvae
    Phyllomedusa: Journal of Herpetology, 2020
    Co-Authors: Santosh M. Mogali, Srinivas K. Saidapur, Bhagyashri A. Shanbhag
    Abstract:

    Behavioral responses of tadpoles of Duttaphrynus melanostictus (Anura: Bufonidae) to cues of starved and fed dragonfly larvae. Tadpoles of Duttaphrynus melanostictus use chemoreception to detect kairomonal cues and excretory metabolites from predatory anuran tadpoles (Hoplobatrachus tigerinus) that consume them. We describe here the behavioral responses of tadpoles of D. melanostictus to predatory dragonfly larvae (Pantala flavescens). The predator’s kairomones (water conditioned by the starved predator) or its diet-derived metabolites released in excreta of predator after consumption of conspecific prey tadpoles were used to simulate predation risk. The tadpoles of D. melanostictus had no behavioral response to predator kairomones. However, the larvae reduced swimming movements and overall time spent in swimming, and had a higher burst speed/swimming velocity in response to water borne cues released from the excreta of predators fed conspecific prey. Thus, just the presence of dragonfly larvae does not elicit defense behaviors in tadpoles of D. melanostictus, but when predation risk is recognized as real (i.e., when tadpoles are exposed to excretory metabolites of predators fed conspecific tadpoles), defense behaviors are activated.

  • Adaptive significance of the transparent body in the tadpoles of ornamented pygmy frog, Microhyla ornata (Anura, Amphibia)
    Acta Herpetologica, 2020
    Co-Authors: Santosh M. Mogali, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    In Southern India, during the Southwest monsoon phase, the newly formed ephemeral water bodies harbour several species of tadpoles as well as some of their predators. Tadpoles of Microhyla ornata dwell in surface or column zones of water. They face predation threat from aquatic insect predators and carnivorous tadpoles of other anurans though they are invisible due to their transparent body form. We tested whether transparent body form of M. ornata tadpoles is a useful attribute against predation by exposing tail fin stained (with the Nile blue) subjects to a naturally occurring predator (Hoplobatrachus tigerinus tadpoles that detect prey using both visual and chemical cues). The study shows that susceptibility of stained M. ornata tadpoles to predation increased significantly compared to the unstained transparent individuals. We conclude that the transparent body form is of great significance in escaping predation during the larval phase of life in M. ornata.

  • strong food odours mask predation risk and affect evocation of defence behaviours in the tadpoles of sphaerotheca breviceps
    Journal of Ethology, 2015
    Co-Authors: Santosh M. Mogali, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    Tadpoles of Sphaerotheca breviceps detect food and predators using waterborne chemical cues (odours), which evoke appropriate behaviour. The present study aimed to determine whether they are capable of resolving the conflict between foraging choice and predator avoidance on encountering both food and predatory chemical cues together. Experiments were designed using an association choice apparatus in which prey tadpoles were given a choice to move themselves close to or away from a given stimulus (food or a predator). Food odours were either strong or weak. Tadpoles of Hoplobatrachus tigerinus (n = 4) were placed in an open-ended mesh cage wrapped in a cheese cloth that provided predator cues. The time spent by the test tadpoles in the predator’s zone or away from it and the time spent feeding were recorded for 10 min (n = 25 trials). When food odours were weak, the prey tadpoles avoided predators and spent significantly more time in the predator-free zone. In contrast, when food odours were strong, they foraged equally in the two zones of the test apparatus regardless of the presence or absence of predators. These findings confirm the inherent ability of S. breviceps tadpoles to distinguish between food and predators, and indicate that strong food odours mask predation risk. We suggest that foraging theory and the predation risk allocation hypothesis should include factors that mislead prey during predation risk assessment and the evocation of defence behaviours.

  • absence of kin discrimination in cannibalistic anuran tadpoles of the frog Hoplobatrachus tigerinus daudin
    Indian Journal of Experimental Biology, 2011
    Co-Authors: Amrapali P Rajput, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    Kin discrimination was tested in the cannibalistic H. tigerinus tadpoles to know whether cannibalism is selectively directed towards non-kin members or it is indiscriminate. The association choice tests were conducted using satiated as well as starved subjects with the assumption that they will associate near non-sibs rather than near sibs with the intention of preferentially cannibalizing them. However, test tadpoles, fed or starved showed a random association choice with sibs and non-sibs, as in the end-bias stimulus blank tests. Therefore it is suggested that cannibalistic H. tigerinus tadpoles do not discriminate sibs from non-sibs and cannibalize on both rather indiscriminately.

  • Levels of Predation Modulate Antipredator Defense Behavior and Metamorphic Traits in the Toad Bufo melanostictus
    Journal of Herpetology, 2011
    Co-Authors: Santosh M. Mogali, Srinivas K. Saidapur, Bhagyashri A. Shanbhag
    Abstract:

    The influence of the presence of nonlethal predators on antipredator defense behavior and metamorphic traits was studied in the toad Bufo melanostictus. Tadpoles reared with caged predaceous tadpoles of Hoplobatrachus tigerinus delayed metamorphosis and also emerged at a smaller size compared to those in a predator-free environment. Different predaceous cues (kairomones, alarm cues and dietary cues, derived after feeding the predator with conspecific prey) induced increase in stationary phase and swimming speed and decrease in swimming spurts and time used for feeding. The intensity of defense behaviors varied with the cue. They were more intense in response to cues of predators fed on conspecific prey item. The response to alarm cues or kairomones or predators fed on heterogeneric tadpole species was similar but lower in magnitude compared to that elicited in response to predators fed on conspecific prey item. Most intense defense behavior in response to the odors of the predator that consumed conspecific members is possibly caused by a combined effect of kairomones, alarm, and dietary cues. The findings suggest that B. melanostictus tadpoles are capable of assessing levels of predation risk and modulating the intensity of their defense behavior in accordance with the perceived threat. Interestingly, despite longer larval period, size at metamorphosis of the toadlets was smaller in the presence of caged predator.

Bhagyashri A. Shanbhag - One of the best experts on this subject based on the ideXlab platform.

  • Behavioral responses of tadpoles of Duttaphrynus melanostictus (Anura: Bufonidae) to cues of starved and fed dragonfly larvae
    Phyllomedusa: Journal of Herpetology, 2020
    Co-Authors: Santosh M. Mogali, Srinivas K. Saidapur, Bhagyashri A. Shanbhag
    Abstract:

    Behavioral responses of tadpoles of Duttaphrynus melanostictus (Anura: Bufonidae) to cues of starved and fed dragonfly larvae. Tadpoles of Duttaphrynus melanostictus use chemoreception to detect kairomonal cues and excretory metabolites from predatory anuran tadpoles (Hoplobatrachus tigerinus) that consume them. We describe here the behavioral responses of tadpoles of D. melanostictus to predatory dragonfly larvae (Pantala flavescens). The predator’s kairomones (water conditioned by the starved predator) or its diet-derived metabolites released in excreta of predator after consumption of conspecific prey tadpoles were used to simulate predation risk. The tadpoles of D. melanostictus had no behavioral response to predator kairomones. However, the larvae reduced swimming movements and overall time spent in swimming, and had a higher burst speed/swimming velocity in response to water borne cues released from the excreta of predators fed conspecific prey. Thus, just the presence of dragonfly larvae does not elicit defense behaviors in tadpoles of D. melanostictus, but when predation risk is recognized as real (i.e., when tadpoles are exposed to excretory metabolites of predators fed conspecific tadpoles), defense behaviors are activated.

  • Adaptive significance of the transparent body in the tadpoles of ornamented pygmy frog, Microhyla ornata (Anura, Amphibia)
    Acta Herpetologica, 2020
    Co-Authors: Santosh M. Mogali, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    In Southern India, during the Southwest monsoon phase, the newly formed ephemeral water bodies harbour several species of tadpoles as well as some of their predators. Tadpoles of Microhyla ornata dwell in surface or column zones of water. They face predation threat from aquatic insect predators and carnivorous tadpoles of other anurans though they are invisible due to their transparent body form. We tested whether transparent body form of M. ornata tadpoles is a useful attribute against predation by exposing tail fin stained (with the Nile blue) subjects to a naturally occurring predator (Hoplobatrachus tigerinus tadpoles that detect prey using both visual and chemical cues). The study shows that susceptibility of stained M. ornata tadpoles to predation increased significantly compared to the unstained transparent individuals. We conclude that the transparent body form is of great significance in escaping predation during the larval phase of life in M. ornata.

  • strong food odours mask predation risk and affect evocation of defence behaviours in the tadpoles of sphaerotheca breviceps
    Journal of Ethology, 2015
    Co-Authors: Santosh M. Mogali, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    Tadpoles of Sphaerotheca breviceps detect food and predators using waterborne chemical cues (odours), which evoke appropriate behaviour. The present study aimed to determine whether they are capable of resolving the conflict between foraging choice and predator avoidance on encountering both food and predatory chemical cues together. Experiments were designed using an association choice apparatus in which prey tadpoles were given a choice to move themselves close to or away from a given stimulus (food or a predator). Food odours were either strong or weak. Tadpoles of Hoplobatrachus tigerinus (n = 4) were placed in an open-ended mesh cage wrapped in a cheese cloth that provided predator cues. The time spent by the test tadpoles in the predator’s zone or away from it and the time spent feeding were recorded for 10 min (n = 25 trials). When food odours were weak, the prey tadpoles avoided predators and spent significantly more time in the predator-free zone. In contrast, when food odours were strong, they foraged equally in the two zones of the test apparatus regardless of the presence or absence of predators. These findings confirm the inherent ability of S. breviceps tadpoles to distinguish between food and predators, and indicate that strong food odours mask predation risk. We suggest that foraging theory and the predation risk allocation hypothesis should include factors that mislead prey during predation risk assessment and the evocation of defence behaviours.

  • absence of kin discrimination in cannibalistic anuran tadpoles of the frog Hoplobatrachus tigerinus daudin
    Indian Journal of Experimental Biology, 2011
    Co-Authors: Amrapali P Rajput, Bhagyashri A. Shanbhag, Srinivas K. Saidapur
    Abstract:

    Kin discrimination was tested in the cannibalistic H. tigerinus tadpoles to know whether cannibalism is selectively directed towards non-kin members or it is indiscriminate. The association choice tests were conducted using satiated as well as starved subjects with the assumption that they will associate near non-sibs rather than near sibs with the intention of preferentially cannibalizing them. However, test tadpoles, fed or starved showed a random association choice with sibs and non-sibs, as in the end-bias stimulus blank tests. Therefore it is suggested that cannibalistic H. tigerinus tadpoles do not discriminate sibs from non-sibs and cannibalize on both rather indiscriminately.

  • Levels of Predation Modulate Antipredator Defense Behavior and Metamorphic Traits in the Toad Bufo melanostictus
    Journal of Herpetology, 2011
    Co-Authors: Santosh M. Mogali, Srinivas K. Saidapur, Bhagyashri A. Shanbhag
    Abstract:

    The influence of the presence of nonlethal predators on antipredator defense behavior and metamorphic traits was studied in the toad Bufo melanostictus. Tadpoles reared with caged predaceous tadpoles of Hoplobatrachus tigerinus delayed metamorphosis and also emerged at a smaller size compared to those in a predator-free environment. Different predaceous cues (kairomones, alarm cues and dietary cues, derived after feeding the predator with conspecific prey) induced increase in stationary phase and swimming speed and decrease in swimming spurts and time used for feeding. The intensity of defense behaviors varied with the cue. They were more intense in response to cues of predators fed on conspecific prey item. The response to alarm cues or kairomones or predators fed on heterogeneric tadpole species was similar but lower in magnitude compared to that elicited in response to predators fed on conspecific prey item. Most intense defense behavior in response to the odors of the predator that consumed conspecific members is possibly caused by a combined effect of kairomones, alarm, and dietary cues. The findings suggest that B. melanostictus tadpoles are capable of assessing levels of predation risk and modulating the intensity of their defense behavior in accordance with the perceived threat. Interestingly, despite longer larval period, size at metamorphosis of the toadlets was smaller in the presence of caged predator.

Nitya Prakash Mohanty - One of the best experts on this subject based on the ideXlab platform.

  • Non-native populations and global invasion potential of the Indian bullfrog Hoplobatrachus tigerinus: a synthesis for risk-analysis
    Biological Invasions, 2020
    Co-Authors: Nitya Prakash Mohanty, Angelica Crottini, Raquel A. Garcia, John Measey
    Abstract:

    Invasive amphibians have considerable ecological and socio-economic impact. However, strong taxonomic biases in the existing literature necessitate synthesizing knowledge on emerging invaders. The Indian bullfrog, Hoplobatrachus tigerinus , a large dicroglossid frog (snout to vent length: up to 160 mm), is native to the Indian sub-continent. Despite the high likelihood of invasion success for H. tigerinus , based on the species’ natural history traits and human use, the status of its non-native populations and global invasion potential has not yet been assessed. In this paper, we provide a profile of H. tigerinus as an invasive species to aid in risk analyses and management of existing populations. We review the available knowledge on non-native populations of H. tigerinus and model its potential distribution in the non-native range and globally; finally, we evaluate its ecological and socio-economic impact using standard impact classification schemes. We confirm successful invasions on the Andaman archipelago and Madagascar. The ensemble species distribution model, with ‘good’ predictive ability and transferability, predicts tropical regions of the world to be climatically suitable for the species. Considering potential for propagule pressure, we predict the climatically suitable Mascarene Islands, Malaysia and Indonesia, and East Africa to likely be recipients of bridgehead invasions. We assign the species two impact scores: both socio-economic and environmental scores were ‘moderate’ with ‘medium’ confidence levels in our assessment. Finally, this synthesis outlines the invasion process of the genus Hoplobatrachus , which is an emerging group of amphibian invaders.

  • No survival of native larval frogs in the presence of invasive Indian bullfrog Hoplobatrachus tigerinus tadpoles
    Biological Invasions, 2019
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Invasive amphibians have considerable negative impacts on recipient ecosystems, however, impact has been assessed for only a few species, limiting risk assessments. In particular, the impact of invasive anurans with carnivorous tadpoles have not been examined thoroughly. The Indian bullfrog ( Hoplobatrachus tigerinus ), native to the Indian sub-continent, is rapidly invading the Andaman archipelago, Bay of Bengal after its recent introduction. We aimed to evaluate the effect of carnivorous H. tigerinus tadpoles on two species of endemic anuran tadpoles Microhyla chakrapanii and Kaloula ghoshi , in a mesocosm experiment. Rapid predation by larval H. tigerinus resulted in no survival of endemic frog tadpoles. Survival of H. tigerinus was density-dependent. The study is timely in elucidating the impact of invasive larval H. tigerinus on native anurans and substantiates the need to manage invasive populations (or potential incursions) of the species on the Andaman archipelago and elsewhere.

  • What's for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago.
    PeerJ, 2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    CITATION: Mohanty, N. P. & Measey, J. 2018. What's for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago. PeerJ, 6:e5698, doi:10.7717/peerj.5698.

  • What’s for dinner? Diet and trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago
    2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Amphibian invasions have considerable detrimental impacts on recipient ecosystems; however, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We assessed the diet of the invasive Hoplobatrachus tigerinus (n = 358), the native Limnonectes spp. (n = 375) and Fejervarya spp. (n = 65) in three sites, across four habitat types and two seasons, on the Andaman archipelago. We found a significant dietary overlap of H. tigerinus with Limnonectes spp., which may lead to competition. Small vertebrates, including several endemic species, constituted a majority of H. tigerinus diet by volume, suggesting potential impact by predation. Diets of the three species were mostly governed by the positive relationship between predator-prey body sizes. Niche breadth analyses did not indicate any significant changes in diet between seasons. Hoplobatrachus tigerinus and Fejervarya spp. chose evasive prey, suggesting that these two species are mostly ambush predators; Limnonectes spp. elected sedentary prey; although a large portion of its diet consisted of other prey types, such electivity indicates ‘active search’ as its major foraging strategy. All three species of anurans mostly consumed terrestrial prey. This intensive study on a new genus of invasive amphibian contributes to the knowledge on impacts of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We stress on the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians.

  • What’s for dinner? Diet and potential trophic impact of an invasive anuran Hoplobatrachus tigerinus on the Andaman archipelago
    PeerJ Inc., 2018
    Co-Authors: Nitya Prakash Mohanty, John Measey
    Abstract:

    Amphibian invasions have considerable detrimental impacts on recipient ecosystems. However, reliable risk analysis of invasive amphibians still requires research on more non-native amphibian species. An invasive population of the Indian bullfrog, Hoplobatrachus tigerinus, is currently spreading on the Andaman archipelago and may have significant trophic impacts on native anurans through competition and predation. We carried out diet analyses of the invasive H. tigerinus and native anurans, across four habitat types and two seasons; we hypothesized that (i) small vertebrates constitute a majority of the H. tigerinus diet, particularly by volume and (ii) the diet of H. tigerinus significantly overlaps with the diet of native anurans, thereby, leading to potential competition. We assessed the diet of the invasive H. tigerinus (n = 358), and individuals of the genera Limnonectes (n = 375) and Fejervarya (n = 65) and found a significant dietary overlap of H. tigerinus with only Limnonectes. Small vertebrates, including several endemic species, constituted the majority of H. tigerinus, diet by volume, suggesting potential impact by predation. Prey consumption and electivity of the three anurans indicated a positive relationship between predator-prey body sizes. Individuals of H. tigerinus and Fejervarya chose evasive prey, suggesting that these two taxa are mostly ambush predators; individuals of Limnonectes chose a mixture of sedentary and evasive prey indicating that the species employs a combination of ‘active search’ and ‘sit and wait’ foraging strategies. All three species of anurans mostly consumed terrestrial prey. This intensive study on a genus of newly invasive amphibian contributes to knowledge of the impact of amphibian invasions, and elucidates the feeding ecology of H. tigerinus, and species of the genera Limnonectes and Fejervarya. We also stress the necessity to evaluate prey availability and volume in future studies for meaningful insights into diet of amphibians

Ayesha S. Ali - One of the best experts on this subject based on the ideXlab platform.

  • RESEARCH ARTICLE International Journal of Pharma and Bio Sciences IN-VITRO ANALYSIS ON THE EFFECTS OF UV-B RADIATION ON THE DORSAL SKIN MELANOPHORES OF INDIAN BULLFROG Hoplobatrachus tigerinus
    2015
    Co-Authors: Sharique A. Ali, Saima Salim, Ayesha S. Ali, Jaya Peter, Cell Biology
    Abstract:

    In vitro studies on the dorsal integumental melanophores of amphibian Hoplobatrachus tigerinus revealed that the artificial UV-B radiation (313nm) at a dose range from 20.0- 24.6 µW/cm 2 for a continuous period of 60- 120 minutes caused an irreversible damage and disruption to the melanophores resulting into permanent clumping and aggregation of cells. However, at lower duration of exposure, the melanophores showed gradual pigment dispersion, most likely as an innate mechanism of defense to attenuate the UVB causing damage. SHARIQUE A.AL

  • 5 ht receptors as novel targets for optimizing pigmentary responses in dorsal skin melanophores of frog Hoplobatrachus tigerinus
    British Journal of Pharmacology, 2012
    Co-Authors: Sharique A. Ali, Saima Salim, Tarandeep Sahni, J Peter, Ayesha S. Ali
    Abstract:

    BACKGROUND AND PURPOSE Biochemical identification of 5-HT has revealed similar projection patterns across vertebrates. In CNS, 5-HT regulates major physiological functions but its peripheral functions are still emerging. The pharmacology of 5-HT is mediated by a diverse range of receptors that trigger different responses. Interestingly, 5-HT receptors have been detected in pigment cells indicating their role in skin pigmentation. Hence, we investigated the role of this monoaminergic system in amphibian pigment cells, melanophores, to further our understanding of its role in pigmentation biology together with its evolutionary significance. EXPERIMENTAL APPROACH Pharmacological profiling of 5-HT receptors was achieved using potent/selective agonists and antagonists. In vitro responses of melanophores were examined by Mean Melanophores Size Index assay. The melanophores of lower vertebrates are highly sensitive to external stimuli. The immediate cellular responses to drugs were defined in terms of pigment translocation within the cells. KEY RESULTS 5-HT exerted strong concentration-dependent pigment dispersion at threshold dose of 1 × 10−6 g·mL−1. Specific 5-HT1 and 5-HT2 receptor agonists, sumatriptan and myristicin. also induced dose-dependent dispersion. Yohimbine and metergoline synergistically antagonized sumatriptan-mediated dispersion, whereas trazodone partially blocked myristicin-induced dispersion. Conversely, 5-HT3 and 5-HT4 receptor agonists, 1 (3 chlorophenyl) biguanide (1,3 CPB) and 5-methoxytryptamine (5-MT), caused a dose-dependent pigment aggregation. The aggregatory effect of 1,3 CPB was completely blocked by ondansetron, whereas L-lysine partially blocked the effect of 5-MT. CONCLUSIONS AND IMPLICATIONS The results suggest that 5-HT-induced physiological effects are mediated via distinct classes of receptors, which possibly participate in the modulation of pigmentary responses in amphibian.

  • In-Vitro Analysis On The Effects Of UV-B Radiation On The Dorsal Skin Melanophores Of Indian Bullfrog Hoplobatrachus tigerinus
    International journal of pharma and bio sciences, 2011
    Co-Authors: Sharique A. Ali, Saima Salim, Ayesha S. Ali, And Jaya Peter
    Abstract:

    In vitro studies on the dorsal integumental melanophores of amphibian Hoplobatrachus tigerinus revealed that the artificial UV-B radiation (313nm) at a dose range from 20.0 24.6 μW/cm 2 for a continuous period of 60120 minutes caused an irreversible damage and disruption to the melanophores resulting into permanent clumping and aggregation of cells. However, at lower duration of exposure, the melanophores showed gradual pigment dispersion, most likely as an innate mechanism of defense to attenuate the UVB causing damage. SHARIQUE A.ALI Dr. Sharique Ali, Head, Dept. of biotechnology, Saifia College of science and education, Bhopal, 462001, India