Date of Award

1997

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Dr. Thomas Pauley

Second Advisor

Dr. Dan Evans

Third Advisor

Dr. Donald Tarter

Fourth Advisor

Dr. Leonard Deutsch

Abstract

Many studies have been conducted on Notophthalmus viridescens viridescens but none have occurred in West Virginia. There are variations in the life history of newts depending on location. In this study, I studied a population of newts in Wayne County, West Virginia from February 1996 to June 1997. I examined population structure, seasonal activity, and reproductive biology.

The population structure can be divided into four classes: egg, larvae, eft, and adult. Eggs at Shoals were deposited in mid-May and larvae were present from mid-June to early September. Larvae began to transform at an approximate total length of 32.8 mm. Red efts were not studied at Shoals but their sizes ranged from a total length of 28.3 mm to a minimum of 78.3 mm. Adult snout-vent length ranged from 41.7-64.0 mm and averaged 49.3 mm.

The sex ratio of adults varied weekly. I captured up to 27 males for every female (27:1) in funnel traps in February and March. In summer, however, females outnumbered males up to 2.5 times The overall sex ratio in funnel traps was 5.1:1. While dipnetting, however, the weekly sex ratios were much closer to even. Overall, from December to June, the sex ratio was 1:1.4. According to current literature, this is the first population of newts studied where females outnumber males.

Seasonal activity patterns of male and female adult newts differ. Sex ratios in funnel traps reflect activity ratios since the traps capture moving animals. Males are much more active than females in the late fall and early spring. While dipnetting, females were captured more often from vegetation. There are also more females in the water in the summer.

Most of the newts at Shoals emigrate from the ponds to terrestrial hibernacula in late April. This migration correlates with the increase in water temperature. Over the summer, newts were found under cover objects and debris. Their skin texture and color and tail height is more suitable for terrestrial living. Newts return to the aquatic environment in mid-November, when ponds refill and water temperature begins to drop in mid-November.

Reproductive biology is divided into the breeding migration, breeding season, and oviposition. There are two breeding migrations at Shoals, one in November and one in February/ and March. In other studies, the smallest adults, metamorphing efts, migrate to ponds in the fall. At Shoals, the smallest adults migrated in the spring. Also, it appears that females do not reproduce their first year.

Current literature describes only a spring breeding season and occasionally a "false fall breeding season9. At Shoals, breeding actually occurs at both seasons. This is determined by looking at sperm waves in males, which showed sperm throughout the entire reproductive tract from November to May, and by witnessing males drop spermataphores in December.

Oviposition was determined visually and by monitoring female egg volume throughout the year. Both of these methods coincided and showed that eggs are deposited in May and June.

Subject(s)

Wayne County (W. Va.).

Notophthalmus viridescens – West Virginia.

Notophthalmus viridescens – Ecology.

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