Mitochondrial DNA diversity in North American herpetofauna: molecular evolution, diversification, and DNA barcoding

Abstract

This thesis builds a reference library of DNA barcodes that provides coverage for 44% of North American species of herpetofauna. It also establishes the utility of the Barcode Index Number system in flagging cases of deeply diverged lineages or hybridization of taxa. The DNA barcode region outperforms 16S rRNA as a tool for species identification and for detecting errors in museum collections. The coupling of information on sequence diversity in the barcode region with that for other mitochondrial genes revealed a correlation between rates of molecular evolution and diversification in North American squamates, but not amphibians. Species formation in squamates appears to be predominantly affected by mutation rate, whereas species diversity in amphibians is likely shaped by life history variables and dispersal ability. Overall, this thesis demonstrates that DNA barcodes are an effective tool for rapid species identification and a good approach for examining mechanisms underlying current biodiversity.