“Reproductive Ecology and Parental Care of a Southeast Asian Treefrog”
Dept. of Biological Sciences, NUS
Supervisor: Asst. Prof David Bickford
Fri 03 Oct 2014: 2.00pm
DBS Conference Room II (S1 Level 3, Mezzaine)
All are welcome
“Parental care is a reproductive strategy that increases fitness of parents by having more surviving offspring. The evolution of parental care is closely linked to sexual selection, mating systems, and other life-history characteristics of an organism. However, parental care can be overlooked or assumed in taxa that are underrepresented in the literature. Consequently, there is a gap between observations and analyses, which limits our understanding of general and taxa-specific trends associated with parental care.
I used in-situ observations and experiments to study the costs and benefits of parental behavior in a Southeast Asian treefrog, Chiromantis hansenae. Female frogs that attended egg clutches contributed to offspring survival primarily by preventing egg desiccation. Parental behavior was the main factor in determining offspring survival and was driven by harsh environmental conditions. Using a predatory katydid, I tested prediction of parental investment theories by observing anti-predator behavior of frogs. Defense against predators and ability to differentiate risk levels was sex-specific and only present in female frogs caring for their eggs. Maternal defense was positively correlated with predation risks and was not influenced by offspring age. These results are contrary to existing theory, which suggests investment ought to be negatively correlated with parental predation risks and affected by offspring age. Finally, I examined hatching plasticity of eggs. When exposed to predation cues, both young and old eggs shortened their embryonic period by hatching early. Hatching time was not correlated with duration of maternal egg attendance. Rather, embryonic response to cues depended on their developmental stage. Younger eggs, not yet capable of hatching, continued to develop after being exposed to predation cues, while older eggs hatched rapidly in response to predation of neighboring eggs.
This is the first empirical, experimentally-driven, parental care research on a Southeast Asian amphibian. Results demonstrate behavioral adaptations by parents and offspring to reduce egg stage mortality. It supports overarching theories of parental care evolution, but provides unexpected trends of parental investment in relation to certain life-history characteristic and environmental factors. This study highlights the importance of examining parental care in underrepresented taxa and geographical regions, and the potential of using C. hansenae as a study system. These findings form a basis for further research on reproductive strategy comparison and hatching plasticity that will lead to improved understandings of decisions involved in both adult and offspring behavior and the evolution of parental care.”
All are welcome”