Mechanisms of Lineage Divergence in the Radiation of Fanged Frogs (Genus: Limnonectes)
In the 300 million years since the divergence of anurans and caudates, frogs have come to represent nearly 90% of all amphibians and (with the exception of Antarctica) occupy most of the major landmasses on Earth. The range of ecological specializations and phenotypes characteristic of frogs facilitated their colonization of every major habitat type from deserts to rainforests. Given current global ecological conservation concerns, there is an ever-increasing need to assess the drivers of radiative herpetological diversity in areas of especially high species richness and endemism. One such hotspot of global endemism and diversity is the Indonesian island of Sulawesi. Though the biological significance of Sulawesi taxa was noted by Alfred Russel Wallace as far back as the 1800’s, in recent years, investigators have not only identified a preponderance of new species on Sulawesi, but several assemblages representing remarkable radiations of novel species.
Herein, I present research that focuses on a recently discovered Sulawesi radiation: that of the so-called ‘fanged frogs’ of genus Limnonectes. This poorly studied assemblage likely includes ~40 species, though only five of have been formally described due to unresolved degrees of morphological, ecological, and molecular disambiguation across species. Very little is known about Sulawesi fanged frog natural- and life histories; thus, the research presented in this compendium explores the ecological mechanisms that facilitated the Sulawesi Limnonectes radiation in effort to counterbalance the current dearth of baseline knowledge about the species comprising this assemblage. To accomplish this objective, I conducted extensive field work across the island and subsequently amalgamated molecular, morphometric, behavioral, physiological, and ecological research applications to characterize differential niche use, reproductive biology, and lineage divergence. In Chapter 1, I describe and diagnose a new terrestrially-nesting Limnonectes species from South Sulawesi. In Chapter 2, I explore cryptic speciation and highlight the discovery of replicate elevational speciation events in a locally sympatric cohort of fanged frog eco-morphs. In Chapter 3, I characterize the eco-physiological drivers of niche partitioning as they apply to cutaneous water loss, behavioral hydro-regulation, and desiccation tolerance. This body of work advances our understanding of Sulawesi fanged frog natural history and underscores the utility of integrative biological research applications for the purposes of determining the interplay between speciation mechanisms and ecological interactions.