UC Santa Cruz

Abstract: The Lesser Sunda Archipelago consists of hundreds of oceanic islands located in southern Wallacea. The Sunda ratsnake, Coelognathus subradiatus, is endemic to the Lesser Sundas and is found on most of the major islands. Mitochondrial DNA was sequenced from snakes representing five of the major islands revealing that levels of sequence divergence between islands range from 2-7%. Phylogenetic analyses recover what can be interpreted as a three-lineage polytomy consisting of lineages from 1) Alor, 2) Sumbawa + Flores, and 3) Timor + Wetar. The archipelago was colonized from the Sunda Shelf ∼7 Myr with subsequent population divergence occurring ∼4.5 Myr, likely resulting in insular species formation.