Date of Award

Fall 12-2016

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Committee Chair

Dr. Brian Kreiser

Committee Chair Department

Biological Sciences

Committee Member 2

Dr. Jake Schaefer

Committee Member 2 Department

Biological Sciences

Committee Member 3

Dr. Mac Alford

Committee Member 3 Department

Biological Sciences

Committee Member 4

Dr. Carl Qualls

Committee Member 4 Department

Biological Sciences

Committee Member 5

Dr. David Duvernell

Committee Member 5 Department

Biological Sciences

Abstract

The mitochondria are responsible for the bulk of energy production in eukaryotes. They possess their own genome that works in conjunction with the nuclear genome to accomplish the extraordinarily important task of energy conversion. When species hybridize there will be a mismatch in evolutionary histories between these two genomes. The deleterious interactions of these genomes have been studied in great detail (i.e. hybrid breakdown). However, little work has been conducted to understand the population genetic, and morphological consequences of wide-ranging replacement. The Fundulus notatus complex is comprised of 3 species: F. notatus, F. olivaceus, and F. euryzonus. Within the complex most pairs will hybridize with at least limited success. Unlike the other members of the species complex, F. euryzonus is restricted to two rivers in the Lake Pontchartrain drainage. In the Amite River F. euryzonus maintains its ancestral mtDNA, but in the Tangipahoa River there is some evidence that there is river-wide mitochondrial introgression (MI) with F. olivaceus. First I used restriction fragment length polymorphisms (RFLPs) and nuclear microsatellite markers to officially document river-wide MI between F. olivaceus and F. euryzonus in the Tangipahoa River along with frequency of hybridization in this system. I then assessed population structure using a traditional microsatellite approach and a genomic scan of single nucleotide polymorphisms. Finally, I looked at morphological variations in body shape using geometric morphometrics. River-wide MI was confirmed in this system making it an interesting natural study system to examine the effect of MI on evolution. Population genetic and population genomic studies revealed species subdivision as expected (more subdivision in F. olivaceus, less subdivision in F. euryzonus), however in the Tangipahoa River F. euryzonus shows at least some subdivision. Morphologically, sexual dimorphism and species variation accounted for most of the variation in shape. The Fundulus notatus species complex is an emerging model for evolutionary study. The work in this manuscript adds to the knowledge base about locations of mitochondrial replacement, population subdivision, and shape variation.

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