Thesis Defense Announcement
To:  The George Mason University Community

Candidate: Christopher Yesmont
Program: M.S. in Biology
Date:   Thursday June 26, 2014
Time:   11:00 a.m.
Place:  George Mason University
             Prince William Campus
             Bull Run Hall, Room 246
Title: "A Phylogenomic Analysis of the Trumpeter Swan (Cygnus buccinator) and Tundra Swan (Cygnus columbianus columbianus)"

Thesis Director: Dr. Ancha Baranova

Thesis Committee:  Dr. Patrick Gillevet, Dr. Dmitri Klimov
A copy of the thesis will be available in the Mercer Library.  All are invited to attend the defense.

Climate change and anthropogenic disturbances have had profound effects on the interactions of animal species. These effects are particularly evident in the interactions between two North American waterfowl, the Trumpeter swan (Cygnus buccinator) and the Tundra swan (Cygnus columbianus columbianus). In these species, habitat changes and disturbances have caused an overlap of their breeding ranges. When hybridized, Trumpeter and Tundra swans produce fertile offspring. Hence, an overlap between these two species is of concern for the swan’s conservation due to introgression of hybrid genes into one or both of the parent species. In order to determine an extent of interspecies hybridization and introgression in the wild, we examined the differences in genomic DNA between the two species and compared these data with mtDNA polymorphism data from the Tundra, Trumpeter, and their hybrids. Next-Generation sequencing was used to compare the genomes of both swan species and to search for differences between the species. We found little difference (<3%) in sequence between the Tundra and Trumpeter genomes. In contrast to nuclear DNA, analysis of single nucleotide polymorphisms in the mtDNA control region (D-Loop) resulted in the differentiation of the two swan species and hybrids.  We attribute this disparity between mtDNA and genomic DNA to the possibility of introgression through repeated backcrossing of hybrids into parent species populations.