Molecular Phylogenetics and Biogeography of Threadsnakes (Serpentes: Leptotyphlopidae)

Open Access
Author:
Adalsteinsson, Solny Arnardottir
Graduate Program:
Biology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • S Blair Hedges, Thesis Advisor
Keywords:
  • Leptotyphlopidae
  • biogeography
  • phylogenetics
Abstract:
The threadsnakes (family Leptotyphlopidae) are one of the most poorly known families of terrestrial vertebrates. The two included genera, Leptotyphlops and Rhinoleptus include over one hundred species, which have a primarily West Gondwanan distribution. In this study, DNA sequencing and molecular phylogenetic methods were used to investigate the diversity, evolutionary history, and biogeography within Leptotyphlopidae. Four mitochondrial genes (12S, tRNA-val, 16S, and cytochrome b) were sequenced for 92 taxa (2971 sites) and an additional five nuclear genes (AMEL, BDNF, C-mos, NT3, RAG1) were sequenced for a subset of 24 taxa (5563 sites). Phylogenetic reconstructions showed that the genus Rhinoleptus is nested within Leptotyphlops, and that the family can be divided into two major clades: a mostly New World clade (which includes Rhinoleptus koniagui and Leptotyphlops bicolor, both African species); and an Old World clade, which is further divided into a Southern African clade, and a mostly West African clade (with the exception of L. longicaudus, from South Africa, and L. blanfordii, from Yemen). Taxon sampling included representatives of nearly all morphology-based species groups. Groups determined from molecular data were compared with classical morphological groups, and radiations among major groups were dated. Most New World species groups were supported, but two major Old World species groups will require revision. The divergence time between Old World and New World leptotyphlopids was estimated to be 91–94 million years ago (95% Credibility Interval: 74–119 Ma), suggesting that the split resulted from the break up of West Gondwana.