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
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.
