Doctor of Philosophy (PhD)
The biodiversity of New Guinea has captivated researchers for hundreds of years. Hosting the world’s richest flora, and one of the richest faunas, its tectonically complex landscape has created a natural laboratory of rapid speciation, complicated biogeography, and fascinating natural history. The fantastic faunas of this region exemplify the selective pressures of island seclusion: Birds-of-Paradise (Paradisaeidae), poisonous blackbirds (Oriolidae: Pitohui), Tree Kangaroos (Dendrolagus), and even a frog that is considered the world’s smallest vertebrate (Paedophryne amauensis). This island also totes impressive snake diversity, but many of its charismatic serpents are shared with Australia; thus, New Guinea’s snake endemism is commonly overshadowed and overlooked. Two lesser known and even lesser studied snake lineages with high species diversity on New Guinea are the New Guinea Worm-eating Snakes (Elapidae: Toxicocalamus Boulenger, 1896) and the Sunda-Papuan Keelback Snakes (Natricidae: Tropidonophis Jan, 1863). For my dissertation, I used a combination of morphology and DNA sequence data to investigate the current systematics and species diversity of these two different lineages. Chapters 2 and 3 each describe new species of Toxicocalamus, but together provide novel insight into unique morphological variation and discussions regarding biogeography and natural history within this genus. Chapters 4 and 5 utilize ultraconserved elements to produce the most extensive phylogenies and estimates of current systematic placements of the genus Tropidonophis. Chapter 4 presents a genus-wide concatenated phylogeny and species tree inferences using a variety of tree-building methodologies. Extensive tree inference permitted detailed divergence dating and the first detailed biogeographical hypothesis of this genus since its morphology-based revision in 1988. Chapter 5 focuses on the phylogeographic history of the one keelback species that crossed the Torres Strait into Australia: Tropidonophis mairii. Building on the genus-wide phylogeny of Chapter 4, I found evidence that T. mairii is paraphyletic, and that T. mairii sensu stricto is probably an Australian endemic. Tropidonophis mairii dispersed to Australia at the end of the Miocene; however, phylogenetics and population structure found that Tropidonophis mairii currently comprises at least one cryptic species that needs to be described from the Australian continent.
Roberts, Jackson Ryan, "Integrative Taxonomy, Systematics, And Natural History of Two Understudied New Guinean Snake Lineages (Elapidae, Toxicocalamus Boulenger, 1896; Natricidae, Tropidonophis Jan, 1863)" (2023). LSU Doctoral Dissertations. 6202.
Austin, Christopher C.
Available for download on Wednesday, July 10, 2030