Habitat alterations in agroecosystems may damage amphibian immune capacity. As agroecosystem extension is increasing worldwide, broader-context knowledge on the effects of agroecosystem stressful conditions on amphibi...Habitat alterations in agroecosystems may damage amphibian immune capacity. As agroecosystem extension is increasing worldwide, broader-context knowledge on the effects of agroecosystem stressful conditions on amphibian immune capacity is crucial for understanding and management of amphibian global declines. However, most studies on ecoimmunology assume synchronal amonggroup immune-response peaks, and focus on immune response after standardized time lapses, neglecting its progress!on. Herein, I compared inflamatory response short-term progression of agro ecosystem and n atural-habitat female and male n atterjack toads Epi da lea calamita, by measuri ng swelling response, once per hour, 6 h following an artificial immune challenge with innocuous antigen phytohemagglutinin. I also compared maximum magnitude of swelling response, irrespective of the moment when it was reached. Habitat differences arose only 3 h after challenge, when naturalhabitat toads showed greater swelling response. Maximum magnitude of swelling response was similar in toads from both habitats. However, agroecosystem toads showed a delayed swelling response as compared with natural-habitat conspecifics, probably as a consequenee of agroecosystem stressful conditions. Such a delay suggests a weaker immune capacity, and consequently impaired anti-pathogen performance. Regarding sex, swelling response magnitude did not differ between males and females. Female swelling response peaked earlier, but that of males was more sustai ned in time, which con tradicts general across-taxa fin dings that males show impaired immune response. Interestingly, results suggest that measuring swelling response only after some standardized period following stimulation may be a simplistic approach and produce unrealistic results. Consequently, studies on ecoimmunology should implement swelling response progression in order to produce unbiased science.展开更多
Chemical defenses are frequently accompanied by salient color patterns actively avoided by predators,a phe-nomenon referred to as aposematism.However,the production of both chemical defenses and pigments is costly,and...Chemical defenses are frequently accompanied by salient color patterns actively avoided by predators,a phe-nomenon referred to as aposematism.However,the production of both chemical defenses and pigments is costly,and is thus expected to be reduced under mild predator pressure.In this work,I compared the size and coloration of parotoid glands(2 dorsal,external swollen structures that secrete toxins in toads)of male and female Epidalea calamita toads from agrosystems and from pine groves.I also quantified the predator attacks received by plas-ticine toad models,whose“parotoid glands”differed in size and color conspicuousness,exposed in each habitat.Predators avoided models with large and conspicuous parotoid glands,but models in agrosystems were more of-ten attacked.Concerning actual toads,agrosystem and male individuals had larger parotoid glands,presumably implying greater production of chemical defenses than in pine grove and female conspecifics.Thesefindings are aligned with previous research suggesting that both agrosystem toads and males in this system are subjected to a more intense predator pressure.Difference between parotoid gland and dorsum coloration was greater in agrosys-tem toads.A marked internal pattern could function as an aposematic signal,which could counteract increased predator pressure.展开更多
Studies on the impacts of variation of biotic interactions at key life cycle stages are crucial to understand the interface between ecological and developmental processes.Predators exert a major impact on prey fitness...Studies on the impacts of variation of biotic interactions at key life cycle stages are crucial to understand the interface between ecological and developmental processes.Predators exert a major impact on prey fitness.Although direct consumption entails the greatest effect,predators can affect prey by means of other mechanisms.For instance,injuries inflicted by failed predation attempts can jeopardize prey fitness,even beyond the short-term.In anuran tadpoles,failed predation typically results in partial tail loss,which is known to reduce swimming speed.However,the potential consequences of tadpole partial tail loss after metamorphosis remain understudied.Because tail materials could be important in conforming metamorph body,we assess the effects of tadpole partial tail loss on metamorph body size in Iberian spadefoot toads Pelobates cultripes.We clipped 55%tail length of pre-tail-resorption stage anesthetized tadpoles,and compared their body size as metamorphs with anesthetized and non-anesthetized non-tail-clipped controls.Also,we tested whether tail length correlated with metamorph body size of individuals of the control groups.Tailclipped tadpoles produced smaller metamorphs than both controls(the bdy size of metamorphs from both controls was similar),which could incur costs in mid-term survival or time to first reproduction.This effect could be particularly important in areas with introduced predators,if autochthonous tadpoles lack defenses against them.Results suggest that materials resorbed from tadpole tail tissues might be reallocated into metamorph body,according to the negative effect of shorter tails in a correlational analysis,and clipped tails in an experimental test,on metamorph body size.展开更多
文摘Habitat alterations in agroecosystems may damage amphibian immune capacity. As agroecosystem extension is increasing worldwide, broader-context knowledge on the effects of agroecosystem stressful conditions on amphibian immune capacity is crucial for understanding and management of amphibian global declines. However, most studies on ecoimmunology assume synchronal amonggroup immune-response peaks, and focus on immune response after standardized time lapses, neglecting its progress!on. Herein, I compared inflamatory response short-term progression of agro ecosystem and n atural-habitat female and male n atterjack toads Epi da lea calamita, by measuri ng swelling response, once per hour, 6 h following an artificial immune challenge with innocuous antigen phytohemagglutinin. I also compared maximum magnitude of swelling response, irrespective of the moment when it was reached. Habitat differences arose only 3 h after challenge, when naturalhabitat toads showed greater swelling response. Maximum magnitude of swelling response was similar in toads from both habitats. However, agroecosystem toads showed a delayed swelling response as compared with natural-habitat conspecifics, probably as a consequenee of agroecosystem stressful conditions. Such a delay suggests a weaker immune capacity, and consequently impaired anti-pathogen performance. Regarding sex, swelling response magnitude did not differ between males and females. Female swelling response peaked earlier, but that of males was more sustai ned in time, which con tradicts general across-taxa fin dings that males show impaired immune response. Interestingly, results suggest that measuring swelling response only after some standardized period following stimulation may be a simplistic approach and produce unrealistic results. Consequently, studies on ecoimmunology should implement swelling response progression in order to produce unbiased science.
文摘Chemical defenses are frequently accompanied by salient color patterns actively avoided by predators,a phe-nomenon referred to as aposematism.However,the production of both chemical defenses and pigments is costly,and is thus expected to be reduced under mild predator pressure.In this work,I compared the size and coloration of parotoid glands(2 dorsal,external swollen structures that secrete toxins in toads)of male and female Epidalea calamita toads from agrosystems and from pine groves.I also quantified the predator attacks received by plas-ticine toad models,whose“parotoid glands”differed in size and color conspicuousness,exposed in each habitat.Predators avoided models with large and conspicuous parotoid glands,but models in agrosystems were more of-ten attacked.Concerning actual toads,agrosystem and male individuals had larger parotoid glands,presumably implying greater production of chemical defenses than in pine grove and female conspecifics.Thesefindings are aligned with previous research suggesting that both agrosystem toads and males in this system are subjected to a more intense predator pressure.Difference between parotoid gland and dorsum coloration was greater in agrosys-tem toads.A marked internal pattern could function as an aposematic signal,which could counteract increased predator pressure.
文摘Studies on the impacts of variation of biotic interactions at key life cycle stages are crucial to understand the interface between ecological and developmental processes.Predators exert a major impact on prey fitness.Although direct consumption entails the greatest effect,predators can affect prey by means of other mechanisms.For instance,injuries inflicted by failed predation attempts can jeopardize prey fitness,even beyond the short-term.In anuran tadpoles,failed predation typically results in partial tail loss,which is known to reduce swimming speed.However,the potential consequences of tadpole partial tail loss after metamorphosis remain understudied.Because tail materials could be important in conforming metamorph body,we assess the effects of tadpole partial tail loss on metamorph body size in Iberian spadefoot toads Pelobates cultripes.We clipped 55%tail length of pre-tail-resorption stage anesthetized tadpoles,and compared their body size as metamorphs with anesthetized and non-anesthetized non-tail-clipped controls.Also,we tested whether tail length correlated with metamorph body size of individuals of the control groups.Tailclipped tadpoles produced smaller metamorphs than both controls(the bdy size of metamorphs from both controls was similar),which could incur costs in mid-term survival or time to first reproduction.This effect could be particularly important in areas with introduced predators,if autochthonous tadpoles lack defenses against them.Results suggest that materials resorbed from tadpole tail tissues might be reallocated into metamorph body,according to the negative effect of shorter tails in a correlational analysis,and clipped tails in an experimental test,on metamorph body size.
