Wood frog Lithobates sylvaticus tadpoles develop in temporary wetlands where high population densities can force tadpoles into aggregations that intensify competition and can lead to cannibalism. However, chemical ala...Wood frog Lithobates sylvaticus tadpoles develop in temporary wetlands where high population densities can force tadpoles into aggregations that intensify competition and can lead to cannibalism. However, chemical alarm cues released from injured conspecifics could also dissuade cannibalism. The purpose of this study was to test mechanisms that may influence can- nibalistic behaviour. We tested whether the tendency of tadpoles to consume conspecifics would increase with the presence of competition and/or cues of profitable diets. Tadpoles placed in 1L experimental containers were tested for feeding initiation times of multiple diets, including conspecific tissues and conspecific tissues combined with chemical cues from the alternative diets （brine shrimp and comrneal）. Tadpoles were tested in the presence and absence of a competitor, and at multiple times over the course of the study. Tadpoles exhibited an altered response to diets over time; however the presence of a competitor reduced re- sponse times to all diets including conspecific tissues. Similarly, the presence of specific diets also reduced the response time of tadpoles to conspecific tissues. These results suggest competition among feeding tadpoles could result in aggressive behaviour leading to indiscriminate predation and cannibalism [Current Zoology 60 （5）： 571-580, 2014 ].展开更多
Wetlands are often created through wetland mitigation to replace lost natural wetlands, but further evaluation is needed to determine the ability of a created wetland to replace lost wetland functions, especially prov...Wetlands are often created through wetland mitigation to replace lost natural wetlands, but further evaluation is needed to determine the ability of a created wetland to replace lost wetland functions, especially providing wildlife habitat. We used a mesocosm design to compare the water quality between three created wetlands and three natural wetlands in West Virginia, USA and to evaluate how the water quality from the two wetland types were able to support metamorphosis in larval spring peepers (<em>Pseudacris crucifer</em>) and wood frogs (<em>Lithobates sylvaticus</em>) across two years (2014-2015). Responses in metamorphosis rates differed between species and between years. Spring peepers displayed similar metamorphosis rates in the created and natural wetlands in both years of the study. Wood frogs displayed similar metamorphosis rates in created and natural wetlands in 2015, but in 2014 wood frogs reached metamorphosis in less time and at a larger body size in the natural wetlands, suggesting that the wood frogs that developed in the natural wetlands may have higher fitness than those that developed in the created wetlands. Water quality was largely similar between created and natural wetlands, although dissolved oxygen, conductivity, and pH varied between mesocosms and wetlands. Our study suggests that created wetlands may be providing partial mitigation in terms of water quality for amphibian development. We recommend that future monitoring of created wetlands include measures of juvenile amphibian recruitment as well as additional habitat variables to better determine the ability of created wetlands to function as amphibian habitat.展开更多
Species with especially close dependence on the environment to meet physiological requirements,such as ectotherms,are highly susceptible to the impacts of climate change.Climate change is occurring rapidly in the Suba...Species with especially close dependence on the environment to meet physiological requirements,such as ectotherms,are highly susceptible to the impacts of climate change.Climate change is occurring rapidly in the Subarctic and Arctic,but there is limited knowledge on ectotherm physiology in these landscapes.We investigated how environmental conditions and habitat characteristics influence the physiological conditions and habitat use of wood frogs(Rana sylvatica)in a Subarctic landscape near Churchill,Manitoba(Canada).We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at specific locations used by radio-tracked frogs.Water loss(R2=0.67)and surface temperature(R2=0.80)of plaster models was similar to that of live frogs.Model-based water loss rates were greater in tundra habitat than in boreal forest and ecotone habitat.Habitat use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster models.Environmental conditions,such as wind speed and ground tem-perature,explained 58%and 91%of the variation in water balance and temperature of plaster models.Maintaining physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future cli-mate change.The ability to predict physiological conditions based on environmental conditions,as demonstrated in our study,can help understand how wildlife will respond to climatic changes.展开更多
文摘Wood frog Lithobates sylvaticus tadpoles develop in temporary wetlands where high population densities can force tadpoles into aggregations that intensify competition and can lead to cannibalism. However, chemical alarm cues released from injured conspecifics could also dissuade cannibalism. The purpose of this study was to test mechanisms that may influence can- nibalistic behaviour. We tested whether the tendency of tadpoles to consume conspecifics would increase with the presence of competition and/or cues of profitable diets. Tadpoles placed in 1L experimental containers were tested for feeding initiation times of multiple diets, including conspecific tissues and conspecific tissues combined with chemical cues from the alternative diets （brine shrimp and comrneal）. Tadpoles were tested in the presence and absence of a competitor, and at multiple times over the course of the study. Tadpoles exhibited an altered response to diets over time; however the presence of a competitor reduced re- sponse times to all diets including conspecific tissues. Similarly, the presence of specific diets also reduced the response time of tadpoles to conspecific tissues. These results suggest competition among feeding tadpoles could result in aggressive behaviour leading to indiscriminate predation and cannibalism [Current Zoology 60 （5）： 571-580, 2014 ].
文摘Wetlands are often created through wetland mitigation to replace lost natural wetlands, but further evaluation is needed to determine the ability of a created wetland to replace lost wetland functions, especially providing wildlife habitat. We used a mesocosm design to compare the water quality between three created wetlands and three natural wetlands in West Virginia, USA and to evaluate how the water quality from the two wetland types were able to support metamorphosis in larval spring peepers (<em>Pseudacris crucifer</em>) and wood frogs (<em>Lithobates sylvaticus</em>) across two years (2014-2015). Responses in metamorphosis rates differed between species and between years. Spring peepers displayed similar metamorphosis rates in the created and natural wetlands in both years of the study. Wood frogs displayed similar metamorphosis rates in created and natural wetlands in 2015, but in 2014 wood frogs reached metamorphosis in less time and at a larger body size in the natural wetlands, suggesting that the wood frogs that developed in the natural wetlands may have higher fitness than those that developed in the created wetlands. Water quality was largely similar between created and natural wetlands, although dissolved oxygen, conductivity, and pH varied between mesocosms and wetlands. Our study suggests that created wetlands may be providing partial mitigation in terms of water quality for amphibian development. We recommend that future monitoring of created wetlands include measures of juvenile amphibian recruitment as well as additional habitat variables to better determine the ability of created wetlands to function as amphibian habitat.
基金approved by IACUC at Southeast Missouri State University and funded by Earthwatch Institute,the Northern Research Fund from the Churchill Northern Studies Centre,and the Office of Student Research at Appalachian State University。
文摘Species with especially close dependence on the environment to meet physiological requirements,such as ectotherms,are highly susceptible to the impacts of climate change.Climate change is occurring rapidly in the Subarctic and Arctic,but there is limited knowledge on ectotherm physiology in these landscapes.We investigated how environmental conditions and habitat characteristics influence the physiological conditions and habitat use of wood frogs(Rana sylvatica)in a Subarctic landscape near Churchill,Manitoba(Canada).We used plaster models to estimate water loss rates and surface body temperatures among different habitat types and at specific locations used by radio-tracked frogs.Water loss(R2=0.67)and surface temperature(R2=0.80)of plaster models was similar to that of live frogs.Model-based water loss rates were greater in tundra habitat than in boreal forest and ecotone habitat.Habitat use of wood frogs was strongly tied with available surface moisture and decreased water loss rates that were observed with plaster models.Environmental conditions,such as wind speed and ground tem-perature,explained 58%and 91%of the variation in water balance and temperature of plaster models.Maintaining physiological conditions may be challenging for semi-aquatic ectotherms in environments vulnerable to future cli-mate change.The ability to predict physiological conditions based on environmental conditions,as demonstrated in our study,can help understand how wildlife will respond to climatic changes.
