Abstract
Poison frogs are well known for their ability to sequester alkaloids from their diet of leaf-litter arthropods for use in defense against predators and pathogens. Australian frogs in the genus Pseudophryne (Myobatrachidae) represent an understudied lineage of poison frogs, with a unique ability to both sequester dietary alkaloids and synthesize pseudophrynamine alkaloids. Herein, we describe the alkaloid profiles and diet of six species of Pseudophryne (P. guentheri [Boulenger, 1882], P. occidentalis [Parker, 1940], P. semimarmorata [Lucas, 1892], P. dendyi [Lucas 1892], P. bibronii [Günther, 1859], and P. coriacea [Keferstein, 1868]) to gain a better understanding of how alkaloid defenses and diet are related within and among species. We characterized and quantified alkaloids using Gas Chromatography-Mass Spectrometry (GC-MS), and assessed diet by way of dissection and examination of stomach contents using light microscopy. We found that alkaloid profiles varied significantly among species, with pumiliotoxins (dietary-derived) and pseudophrynamines (biosynthesized) being the most abundant alkaloids. Pseudophryne bibronii and P. dendyi contained mostly dietary-derived alkaloids, whereas P. coriacea, P. guentheri, P. semimarmorata, and P. occidentalis possessed mostly biosynthesized alkaloids. The stomachs of all the studied species were largely empty, containing mostly soil and few partially digested insects. Our data suggest that frogs eat minimally during the breeding season. Therefore, a decrease in dietary alkaloids may be compensated by the biosynthesized pseudophrynamines, which could allow Australian poison frogs to remain defended from predators during this vulnerable time period.
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References
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Acknowledgements
We value DEI efforts and took this into account in completing this work. Our team includes representatives from three universities from two countries, as well as established researchers and undergraduate authors. We would like to thank P. Byrne and S. Keogh for discussions about this research, N. Mitchell and S. Macdonald for their assistance in Western Australia, as well as B. Symula and N. Clemann for assistance in eastern Australia. This work was supported by the Endeavour Fellowship to JPL offered by the Australian Department of Education and Training (ERF RDDH 151726 2015). Animals were collected under permits for New South Wales (SL101733), Victoria (10007622), and Western Australia (SF010838) with IACUC Approval 15-012 from the University of Mississippi and ACEC (A11490) from Western Sydney University.
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JPL was supported by the Endeavour Fellowship offered by the Australian Department of Education and Training (ERF RDDH 151726 2015).
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MS and JPL wrote the first draft of the manuscript, and all authors participated in the revision of this draft. JPL and RAS worked on the final version of the manuscript. MS and LP developed the diet analysis protocol, and MS dissected and documented stomach contents. VD and RAS performed the alkaloid analyses among frogs and analyzed patterns. JPL and KDLU developed the project. JPL collected the samples. All authors contributed to the final manuscript and approved of its publication.
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Sague, M., Dudaitis, V., Plumert, L. et al. Alkaloid-based chemical defenses and diet in six species of Australian poison frogs in the genus Pseudophryne (Myobatrachidae). Evol Ecol (2023). https://doi.org/10.1007/s10682-023-10269-x
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DOI: https://doi.org/10.1007/s10682-023-10269-x