Humans are not the only animals that recognize familiar individuals. In fact, social recognition has been documented in many different species, yet little is known about how animals learn to recognize familiar individuals and how this behavior evolves. Frogs may be an ideal taxonomic group for comparative research on social recognition since males of some territorial species recognize and respond less aggressively to the calls of familiar neighbors – a common form of social recognition – and the diversity of territorial systems suggests there may be many independent origins of neighbor recognition. However, tests of this behavior in frogs are few and taxonomically restricted. Mark Bee, Michael Reichert, and I recently reviewed the research on neighbor recognition in frogs (Bee, Reichert, and Tumulty 2016)
My dissertation research takes an integrative an comparative approach to understanding social recognition in frogs. I am conducting playback experiments in several species of rocket frogs (family Aromobatidae) to test if males discriminate between the calls of neighbors and strangers. In particular, I am focusing on a comparison of two closely related species: golden rocket frogs (Anomaloglossus beebei) and Kai rocket frogs (A. kaiei), both native to Kaieteur National Park in Guyana. These two species have very different reproductive ecology; A. beebei defend territories and reproduce in large terrestrial bromeliads, while A. kaiei defend territories on the forest floor like many other species of rocket frogs. For my dissertation I am characterizing the territorial systems of these two species, and doing acoustic playback experiments and learning-discrimination experiments to understand how reproductive ecology influences territorial systems and communication systems in turn.
Parental Care and Mating Systems
Relative levels of parental care by males and females have a strong influence on the mating system of a species. Typically, the sex that invests more into offspring is the limiting sex when it comes to reproduction, and the mating systems of many species are a reflection of the non-limited sex (usually males) competing for the limited sex (usually females). But what happens if males and females both care for offspring? It is thought that selection for biparental care could maintain a monogamous mating system if the value of cooperation in care for offspring exceeds the value of polygamy for either sex. This “biparental care hypothesis” draws support mainly from birds, many of which are socially monogamous and need two parents to raise chicks. For my master’s thesis with Kyle Summers (East Carolina University), we tested this hypothesis for the first time in an amphibian.
Previous research done by Jason Brown and Kyle Summers has shown that mimic poison frogs (Ranitomeya imitator) are monogamous. In this species, males guard eggs and transport newly-hatched tadpoles to small pools of water in the axils of plant leaves (phytotelmata), then lead females to these pools and females feed the tadpoles unfertilized eggs. Furthermore, this work has shown that biparental care in this species is associated with the use of extremely small pools of water as breeding resources, where food is scarce and tadpoles need to be fed by parents to survive. Building on this research, I tested the biparental care hypothesis for the evolution of monogamy by quantifying the importance of egg feeding and male parental care for tadpole growth and survival (Tumulty, Morales, and Summers 2014). Sure enough, tadpoles that were fed more eggs grew faster and were more likely to survive. When I removed the male parents from some families their tadpoles suffered; tadpoles being raised only by a female parent had lower growth and survival than those raised by monogamous pairs. These results support the hypothesis that selection for biparental care in this mimic poison frogs maintains monogamy, since monogamous pairs can raise more successful offspring than single parents alone.
This research was featured in an article for the Estonian newspaper “Sirp”: http://www.sirp.ee/s1-artiklid/c21-teadus/monogaamia-evolutsioonist/
A common theme of my research is the importance of reproductive ecology to the evolution and function of social behavior. I believe that a good understanding of the natural history and ecology of an organism is critical to understanding the significance of its behavior. Neotropical poison frogs (families Dendrobatidae and Aromobatidae) are a taxonomic group where the link between social behavior and reproductive ecology is especially important since these frogs care for their eggs and tadpoles and the types of reproductive resources they use are associated with levels of parental care, sexual selection, and mating systems. Thus, these frogs are an excellent group for comparative research on the ecology and evolution of social behavior, and they have been the subjects of many excellent field studies. Kyle Summers and I reviewed much of this research in a recent book chapter (Summers & Tumulty 2013).