Date of Award

Spring 2007

Project Type


Program or Major


Degree Name

Master of Science

First Advisor

James T Taylor


Thamnophis sirtalis, the Common garter snake, is a wide-ranging North American snake exhibiting great variation in morphology and life-history attributes across its range. This thesis studied reproductive variation and molecular phylogeography of T. s. sirtalis, the Eastern garter snake, and T. s. pallidulus, the Maritime garter snake, in populations from New England in 2005 and 2006. Pregnant female snakes were captured and held in captivity until parturition, and measurements were taken on parent and offspring for comparisons across years and locations. Tissue samples were taken from adult snakes for mtDNA sequencing and subsequent phylogenetic comparisons. No substantial trends were observed in female or clutch characteristics, but offspring were consistently largest from the northernmost population. Low genetic divergence was observed among New England populations, suggesting a recent and continuous recolonization post-glaciation. Both reproductive and molecular data suggest that no substantial differences exist between the two T. sirtalis subspecies in New England.