Date of Award

1987

Degree Name

Biological Sciences

College

College of Science

Type of Degree

M.S.

Document Type

Thesis

First Advisor

Ralph Taylor

Second Advisor

Dan Evans

Third Advisor

Alan White

Abstract

A population of a midwestern naiad, Uniomerus tetralasmus was discovered in West Virginia in 1984. A survey of this disjunct population was undertaken between May and December 1986. A study of the reproductive and early developmental stages was the primary objective. A description of the morphology, a shell aberration, a study of its ability to estivate, a correlation between sex types in lentic and lotic environments and explanations for its expansion to West Virginia are included as well. When permanent slides were made of the naiad's reproductive organs, the naiad was found to be a functional hermaphrodite. Eggs and sperm were found to be mature simultaneously and in proportions indicating the possibility for self-fertilization. Gravid "females" were found only in May suggesting that these are bradytachtic or "short-term breeders". The eggs, sperm and glochidia have been preserved, photographed and described. A statistical study of the morphology of the shells has been included. Length, width, depth and age as indicated by growth rings have been recorded. While completing this morphological study, a shell aberration was discovered. An indentation was located approximately one-third of the length from the narrowest edge of the shell and occurred in about half of the shells surveyed. The aberration is thought to be caused by genetic factors. An observation of the estivation ability of the naiad was recorded. Several naiads were allowed to undergo cool, dry conditions for approximately two months. The naiads sealed themselves in their shells with a cement-like secretion presumably to prevent water loss. When they were opened, a number of crystals were found in a thick, mucous strand. The crystal is believed to be a product of metabolism. An attempt to show the correlation between specimens from lentic and lotio environments proved unsuccessful. The reason for this being the difficulty in obtaining specimens from a lotio environment. Also, possible explanations for how this population arrived in West Virginia, whether by stock fish, waterfowl, flooding or through other means are given.

Subject

Unionidae - West Virginia

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