Date of Award

Summer 1975

Document Type


Degree Name

Master of Science (MS)


Biological Sciences



Committee Director

John R. Holsinger

Committee Member

John Richardson

Committee Member

Paul Homsher

Call Number for Print

Special Collections LD4331.B46 H48


The amphipod Gammaru. minus has three morphotypes in its Appalachian range : (1) a spring form with well-developed eyes, (2) an intermediate cave form with slightly reduced eyes, and (3) an extreme cave form with greatly reduced eyes. This study compares the genetic structure of populations in two karst areas and analyzes the genetics of populations of the three morphotypes.

Genetic data were collected from populations in the Ward's Cove, Virginia and Greenbrier Valley, West Virginia karst areas using zone electrophoresis zymograms. One hundred percent of the Ward's Cove populations are polymorphic at both MDH-1 and PEP 1 loci with alleles and allelic frequencies nearly identical. Polymorphism is low in most of the Greenbrier Valley populations. The allelic frequencies are also nearly identical.

The well integrated subterranean drainage systems of both the Greenbrier Valley and Ward's Cove karst areas favor intermittent gene flow among populations. Gene flow and random drift are probably responsible for the low levels of genetic variability. The genetic homogeneity seen in populations in certain drainage basins within these two karst areas is probably due primarily to gene flow.

No consistent genetic differences were found between the three morphotypes A preliminary study of the chromosomal make-up also indicates no differences ( 2N·= 53-54 ). This indicates that photoreceptor regression has not been accompanied by a major reorganization of the genome. Also, based on these data there is nothing to warrant the division of the species into separate taxa.


In Copyright. URI: This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).