title: Genus-level phylogeny of snakes reveals the origins of species richness in Sri Lanka.
abstract: Snake diversity in the island of Sri Lanka is extremely high, hosting at least 89 inland (i.e., non-marine) snake species, of which at least 49 are endemic. This includes the endemic genera Aspidura, Balanophis, Cercaspis, Haplocercus, and Pseudotyphlops, which are of uncertain phylogenetic affinity. We present phylogenetic evidence from nuclear and mitochondrial loci showing the relationships of 40 snake species from Sri Lanka (22 endemics) to the remaining global snake fauna. To determine the phylogenetic placement of these species, we create a molecular dataset containing 10 genes for all global snake genera, while also sampling all available species for genera with endemic species occurring in Sri Lanka. Our sampling comprises five mitochondrial genes (12S, 16S, cyt-b, ND2, and ND4) and five nuclear genes (BDNF, c-mos, NT3 RAG-1, and RAG-2), for a total of up to 9582bp per taxon. We find that the five endemic genera represent portions of four independent colonizations of Sri Lanka, with Cercaspis nested within Colubrinae, Balanophis in Natricinae, Pseudotyphlops in Uropeltidae, and that Aspidura+Haplocercus represents a distinct, ancient lineage within Natricinae. We synonymize two endemic genera that render other genera paraphyletic (Haplocercus with Aspidura, and Cercaspis with Lycodon), and discover that further endemic radiations may be present on the island, including a new taxon from the blindsnake family Typhlopidae, suggesting a large endemic radiation. Despite its small size relative to other islands such as New Guinea, Borneo, and Madagascar, Sri Lanka has one of the most phylogenetically diverse island snake faunas in the world, and more research is needed to characterize the island's biodiversity, with numerous undescribed species in multiple lineages.
authors.affiliation: Dept. of Biological Sciences, The George Washington University, 2023 G. St., NW, Washington, DC 20052, United States. rpyron@colubroid.org.
authors.forename: R Alexander
authors.initials: RA
authors.lastname: Pyron
authors.forename: H K Dushantha
authors.initials: HK
authors.lastname: Kandambi
authors.forename: Catriona R
authors.initials: CR
authors.lastname: Hendry
authors.forename: Vishan
authors.initials: V
authors.lastname: Pushpamal
authors.forename: Frank T
authors.initials: FT
authors.lastname: Burbrink
authors.forename: Ruchira
authors.initials: R
authors.lastname: Somaweera
mesh_terms: D063147:Animal Distribution; D000818:Animals; D001483:Base Sequence; D044822:Biodiversity; D004272:DNA, Mitochondrial / Q000235:genetics; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012911:Snakes / Q000145:classification* / Q000235:genetics*; D013188:Sri Lanka
chemical_list: D004272:DNA, Mitochondrial