Reproductive ecology and space use in Neotropical Poison Frogs

Project leader: Eva Ringler, Max Ringler

Collaborators: Andrius Pasukonis, Bibiana Rojas

Funded by the Austrian Science Fund (FWF) via the Projects P24788, and T699.

https://www.fwf.ac.at/

Amphibians are unique among vertebrates in that almost all members have complex life cycles with two distinct free-living stages that face entirely different challenges in their environments. In the project “Determinants of fitness in species with complex life cycles” we have investigated the effects of relatedness and parental behaviour on individual reproductive success and the associated patterns of space use in the Neotropical frog Allobates femoralis. The controlled introduction of 1800 genetically sampled tadpoles on a river island allowed us to evaluate the use of microsatellite markers for genetic across-stage mark–recapture studies in amphibians. Our results show that microsatellites are a highly powerful tool for studying amphibian populations on an individual basis (Ringler et al. 2014). The ability to track individual tadpoles throughout metamorphosis until adulthood will be of substantial value for future studies on amphibian population ecology and evolution. By molecular parentage analysis of tadpoles sampled during tadpole transport, or that had been deposited in water bodies, and their putative parents we were able to investigate the logistics of tadpole transport and the associated patterns of space use in this species (Ringler et al. 2018). We found that A. femoralis strategically adjust the number of tadpoles on their backs according to transporting distance and distribute tadpoles across several water bodies as a bet-hedging strategy (Erich et al. 2015). These findings demonstrate that poison frogs are highly flexible and capable of strategic planning when it comes to parental decision-making.

We also undertook a resource supplementation experiment, which showed that aquatic sites are a limited resource for A. femoralis. After the installation of artificial pools, the population size almost doubled as a result of increased autochthonous recruitment (Ringler et al. 2015) The findings have major implications for conservation and ecology, highlighting the importance of non-trophic relationships and showing that human “ecosystem engineering” can have a major role in efforts against the global amphibian decline.

The combination of spatial translocations and individual tracking and the use of the island setup allowed us to investigate orientation abilities and homing performance of A. femoralis males in both familiar and novel environments (Pašukonis et al. 2013,2016; Beck et al. 2017). Our findings suggest that poison frogs rely on spatial learning to find their way in their local area.

Amphibians have traditionally been assumed to be largely instinct‐bound with highly stereotyped behaviour. In the project “Behavioural flexibility in anuran amphibians” we have tried to challenge this notion by conducting a series of behavioural experiments in two anuran amphibians in their natural habitat, as well as under laboratory conditions. One major part of this project focused on parental decision‐making in the neotropical poison frog Allobates femoralis. Via male removal experiments we discovered that in this species with obligatory male parental care females flexibly compensate the loss of their offspring’s father (Ringler et al. 2015). Clutch manipulation experiments further revealed different offspring discrimination strategies are employed by male and female A. femoralis, highlighting respective sex‐specific differences in risks and costs of misdirected care (Ringler et al. 2016). Male removal experiments in the field suggested that males exhibit cannibalistic behaviour when taking over a new territory. Follow‐up experiments in the lab confirmed this hypothesis (Ringler et al 2017) and showed that also females prey on unrelated clutches in the absence of a guarding male (Spring et al 2019). We also recently discovered that parental behaviour (i.e. tadpole transport) can be experimentally induced in both male and female A. femoralis, by transferring unrelated tadpoles to the backs of adults in the field (Pašukonis et al 2017).

Selected Publications:

Ringler E, Rojas B, Stynoski J, Schulte L (2023) What amphibians can teach us about the evolution of parental care. Annual Review of Ecology, Evolution, and Systematics 54: 43–62. https://doi.org/10.1146/annurev-ecolsys-102221-050519

Schulte LM, Ringler E, Rojas B, Stynoski JL (2020) Developments in Amphibian Parental Care Research: History, Present Advances and Future Perspectives. Herp. Monogr. 34(1): 71–97. [pdf] https://doi.org/10.1655/HERPMONOGRAPHS-D-19-00002.1