Frog Research

 

Animal personality and sexual selection

Naturalists and pet owners have long intuitively recognized that individual animals show ‘personality’. Only within the last decade the topic ‘animal personalities’ have received considerable attention in the scientific community, after consistent individual differences in behaviour have been documented across a wide range of taxa, including species with very simple nervous systems, such as sea anemones and hermit crabs.

At the same time, these behavioural differences are expected to have dramatic effects on an individual’s fate - in terms of produced offspring and own chances of survival. Previous research has mainly focused on the response of single individuals to changes in their environment or to specific test conditions. However, most behaviour in the context of reproduction and survival is expressed in a social context, with two or more individuals involved.

Therefore, in our proposed project “Show-off or shy boy? The interplay between animal personality and sexual selection” we will investigate how personality differences are reflected in behaviours such as male-male competition and space use, mate choice, and parental care; and how these differences ultimately affect an individual’s survival and reproductive performance.

The project will focus on the model species Allobates femoralis, a Neotropical poison frog with a prolonged breeding season, pronounced male territoriality, and male parental care. The study will be carried out in an experimental island population in French Guiana. The ability to monitor, assay, and track an entire animal population in its natural habitat in an island setup over several generations makes this project exceptional.

All individuals are genetically sampled and their position in a consistent pedigree is known. By identifying respective costs and benefits of specific personality profiles, the proposed project will help us to better understand how behavioural variation can persist over evolutionary time.

Funded by Funded by the Austrian Science Fund (FWF), 2018 - 2021

© Michael Stiegler
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Behavioural Flexibility in Anuran Amphibians

In this project we have tried to challenge the prejudice that “frogs are stupid” by conducting a series of behavioural experiments both in anuran amphibians in their natural habitat, as well as under laboratory conditions. One major part of this project has focused on parental decisionmaking 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. Clutch manipulation experiments further revealed different offspring discrimination strategies are employed by male and female A. femoralis, highlighting respective sexspecific differences in risks and costs of misdirected care. Male removal experiments in the field suggested that males exhibit cannibalistic behaviour when taking over a new territory.

Followup experiments in the lab confirmed this hypothesis. 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. Taken together, our research clearly demonstrates that that poison frogs exhibit highly flexible parental behaviours and are capable of strategic planning when it comes to parental decision-making.

In the course of this project Eva Ringler also spent one year at the University of California Los Angeles (UCLA), where she performed brain imaging experiments (using fMRI technology) to study directed attention to acoustic stimuli in the frog brain. This is the first study that investigates brain activity using functional MRI in anuran amphibians, and will thus provide a fundamental basis for any followup study using fMRI in amphibians, or other nonmodel organisms.

Funded by the Austrian Science Fund (FWF), 2015 - 2019

© Andrius Pašukonis
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Determinants of fitness in species with complex life cycles

In the project “Determinants of fitness in species with complex life cycles” we have investigated how sexual and natural selection shape reproductive behaviours in the Neotropical frog Allobates femoralis. To this end we have installed both, an ex-situ breeding population at the University of Vienna and an experimental in-situ population of A. femoralis on a river island in French Guiana, where we undertook population-wide genetic sampling as well as specific behavioural experiments under controlled conditions.

The controlled introduction of 1800 genotyped tadpoles allowed us to evaluate the use of genetic fingerprinting for mark–recapture studies across metamorphosis in amphibians. Our results show that microsatellites markers are a highly powerful tool for studying amphibian populations on an individual basis. The ability to track individual tadpoles throughout metamorphosis until adulthood will be of substantial value for future studies on amphibian population- and behavioural ecology and useful for species conservation projects.

By molecular parentage analysis of tadpoles we were able to investigate the logistics of tadpole transport and the associated patterns of space use in this species. We found that A. femoralis males distribute tadpoles across several water bodies as a bet-hedging strategy; and we discovered that females flexibly compensate for missing male care. Experiments in the lab further revealed that males and females use different offspring discrimination strategies that may lead to either parental or aggressive (cannibalistic) behaviour.

These findings demonstrate that poison frogs are highly flexible and capable of strategic planning when it comes to parental decision-making. The combination of spatial translocations, individual tracking, cross-foster experiments, and the use of the closed island setup further allowed us to investigate orientation abilities and homing performance of A. femoralis in both familiar and novel environments.

Our findings suggest that poison frogs use spatial learning to improve orientation in their local area, and may also use olfaction to explore novel reproductive resources. We also undertook a supplementation experiment with artificial water bodies, which showed that suitable aquatic sites for tadpole deposition are a limited resource. After the installation of the pools, the population size almost doubled.

These findings are of importance for the conservation of amphibians, as they highlight the role of non-trophic interactions between species and suggest intervention routes to mitigate the global amphibian decline.

Funded by the Austrian Science Fund (FWF), 2012 - 2017

© Eva Ringler
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