Deborah Shaffer

ABSTRACT

The eastern newt (Notophthalmus viridescens viridescens) is ubiquitous throughout eastern North America. Yet despite its commonness, gaps exist in our understanding of its population structure, primarily in the connectivity of its breeding ponds. Adult newts show extreme philopatry to breeding ponds, so it has been surmised that the terrestrial juvenile eft stage is responsible for maintaining connectivity and colonizing vacant ponds. Mark and recapture studies have provided some insight into the population dynamics of the newt but to date genetic analyses have focused on the population structures of the rarer subspecies of N. viridescens or on the phylogenetic relationships between the subspecies.

To learn more about the population structure I evaluated genetic sequence data of newt populations from ponds located in the Shenandoah Mountains west of Harrisonburg, Virginia and in the Massanutten Mountains. I assessed levels of sequence differentiation between ponds separated by mountain valleys and various levels of habitat disturbance to detect barriers to eft dispersal. The lack of sequence differentiation between these populations indicates a collection of breeding populations connected through gene flow, supporting the hypothesis that newts exist as an intrametapopulational panmixis.

The long-term survival of the eastern newt is dependent on the connectivity of the sub-populations of the regional metapopulation. As such, conservation efforts should focus on maintaining connectivity between populations. This study has called attention to the need for further genetic research to identify populations at risk of genetic isolation. In this talk I will discuss the results of this population study as well as the many obstacles encountered during this project, both in the field and in the genetics lab.