Electronic Theses and Dissertations

Date of Award

5-1-2026

Document Type

Dissertation

Degree Name

Ph.D. in Biological Science

First Advisor

Ryan Garrick

Second Advisor

Susan Adams

Third Advisor

James Cizdziel

School

University of Mississippi

Relational Format

dissertation/thesis

Abstract

Crayfish are a diverse group of freshwater invertebrates spanning every continent except mainland Africa and Antarctica. While there are over 640 species of crayfish described, many taxonomic problems impede research and conservation of these crustaceans. This dissertation first examines the effectiveness of DNA barcoding for discovering and identifying crayfish species. Online repositories of crayfish mitochondrial cytochrome C oxidase subunit I sequences were used to determine the presence of global barcoding gaps (species discovery) in genera and local barcoding gaps (species identification) in species, while also investigating the presence of cryptic diversity through species delimitation analyses. Global barcoding gaps were present in only four of eight genera and local barcoding gaps were present in only 30 of 81 species, with species delimitation analyses indicating high levels of cryptic diversity. These results support prior concerns that current crayfish taxonomy may be inadequate, and many species may need taxonomic revisions. Thus, integrative species delimitation was used to explore species boundaries in the genera Hobbseus and Creaserinus. Both genera have species of conservation concern with taxonomic issues hampering management strategies. Analyses using morphology, geography, and mitochondrial and nuclear DNA delimited seven Hobbseus species, which included the discovery of an undescribed species and the consolidation of two described species. Creaserinus were evaluated using morphology, geography, and nuclear DNA, with six species delimited, including the discovery of an undescribed species.

Download

Available for download on Tuesday, August 03, 2027

Share

COinS