Date of Award

Spring 5-13-2017

Level of Access

Open-Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Wildlife Ecology and Wildlife Conservation

Advisor

Aram Calhoun

Second Committee Member

Malcolm Hunter

Third Committee Member

James Bogart

Additional Committee Members

Daniel Harrison

Michael Kinnison

Abstract

Unsexual Salamanders within the Blue-Spotted Salamander Complex carry combinations of ambystomatid genomes (those of Blue-Spotted Salamanders, Ambystoma laterale, and Jefferson Salamanders, A. jeffersonianum in Maine). They are nearly all female, breed in wetlands, and use sperm of related species to reproduce. Little is known about their ecology to guide the conservation of this unique lineage. I examined breeding site occupancy, demographics, orientation, and terrestrial habitat selection of Unisexual Salamanders in comparison to Blue-Spotted Salamanders and other amphibians. I compared statistical tests of orientation to determine which was most appropriate for pitfall data.

Unisexual Salamander occupancy at breeding sites was positively related to counts of captured Blue-Spotted Salamanders, hydric soil, and vegetation characteristics. Blue-Spotted Salamander occupancy was related to the same vegetation characteristics, but Spotted Salamander occupancy was related to other characteristics.

I examined demographics and orientation of Unisexual Salamanders, Blue-Spotted Salamanders, Spotted Salamanders, and Wood Frogs (Lithobates sylvaticus) at four vernal pools. The ratio of juveniles per female was not significantly different among taxa, though only 1% of my Blue-Spotted Complex Salamander populations were males. I used simulated and field data to examine the effects of common scenarios on statistical tests, and found the Rayleigh test to be most suitable as a test of uniformity and the Kruskal-Wallace test the most suitable test of homogeneity. Orientation of Blue-Spotted Complex Salamanders was generally like that of other taxa.

Telemetered Unisexual Salamanders migrated distances similar to those of parent species, and used sites with high numbers of burrows, lower temperatures, and low cover by forest floor vegetation. Ninety percent of Unisexual Salamanders stayed within the forest matrix, but some migrated to disturbed areas such as backyards.

These findings relate Unisexual and Blue-Spotted Salamanders to their community and habitat. These two salamanders are similar in their use of both breeding sites and non-breeding habitat, but the former may range beyond the reach of this sperm-host. Additionally, managers who conserve terrestrial habitat near the pool for other species may also be aiding in the movements of sympatric Blue-Spotted Complex Salamanders, and pools with few males may still support viable populations of the complex.

Share