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Dryad

Agalychnis callidryas and A. spurrelli egg masses

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Jul 27, 2022 version files 10.82 KB

Abstract

Syntopic populations of species provide a unique opportunity to examine divergence of adaptive traits that suggest character displacement when compared with allopatric populations of those species. Past work on syntopic populations of tree frogs, Agalychnis callidryas and A spurrelli documented differences in embryonic risk responses. Due to a serendipitous opportunity, we sampled egg masses from these species oviposited during a breeding aggregation at a forested wetland during July 2017 in the Puntarenas Province of Costa Rica. We collected data on egg masses of the two species including oviposition site and evidence of predation. Both species oviposited on vegetation around the perimeter of the wetland. Additionally, we found that A. callidryas, the species that was previously documented as hatching quickly in response to snake predation took advantage of canopy vegetation overhanging the wetland for oviposition, sites more available to arboreal snakes. This canopy vegetation was not used by A spurrelli. Conversely, A spurrelli, the species shown to respond more strongly to submergence by hatching early, oviposited on vegetation directly emerging from the wetland, sites not used by A callidryas. This divergence of reproductive and ecological traits is not seen in allopatric populations of the same species. These findings suggest that character displacement in oviposition site may have caused differences in selection pressure on embryonic behavior.