Search results

Phylogenetics Systematics and Evolution of Fishes and Mussels

My research in the area of phylogenetic systematics has involved using DNA sequence data to improve our understanding of the evolutionary relationships of organisms.  Phylogenetic hypotheses provide a framework to address questions as diverse as species delineation, biogeography, and character evolution.

Past research projects on the Centrarchidae and the Petromyzontiformes have been sponsored by the National Science Foundation. Topics of more recent research includes freshwater shrimps in the family Atyidae and freshwater mussels in the genus phylogeny of freshwater mussel genus Ptychobranchus.

2015 Surveying for freshwater mussels on the Rio Grande

I assisted some colleagues with surveying for Texas hornshell mussels on the Rio Grande in September. It was a great trip overall and I was able to collect some samples of two species of interest for a future phylogeography project.

Mussel sampling crew on the Rio Grande River

A comparison of genetic diversity and population structure of the endangered scaleshell mussel (Leptodea leptodon), the fragile papershell (Leptodea fragilis) and their host-fish the freshwater drum (Aplodinotus grunniens)

Submitted by kjroe on Thu, 10/12/2017 - 16:25

The larvae of freshwater mussels in the order
Unionoida are obligate parasites on fishes. Because adult
mussels are infaunal and largely sessile, it is generally
assumed that the majority of gene flow among mussel populations
relies on the dispersal of larvae by their hosts. The
objective of this study was to compare the genetic diversity
and the degree of congruence between the population structures
of two related freshwater mussels Leptodea leptodon
and Leptodea fragilis and their fish host, Aplodinotus grunniens.
Host specificity in parasites has been shown to result
in greater congruence between the population structures of
the two interacting species, and assessing the congruence
of genetic structure of the endangered L. leptodon with its
sister species L. fragilis and their sole host is an important
step in understanding the impact of host dispersal on population
structure. Analysis of microsatellite data indicated that
despite its imperiled status, L. leptodon displayed greater
genetic diversity than the more common L. fragilis. However,
the population structures of all three species were
incongruent even in the presence of substantial gene flow.
Other factors such as habitat specificity may play a role in
generating the differences in population structure observed.