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Neuroscience Research Seminar: Aya Nusir (PhD Candidate)

Oct 27, 2025, 3:00 - 4:00 PM

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Mid-Holocene reductions of equatorial Atlantic Ocean variability and linkages to high-latitude Southern Atlantic forcing

Oct 29, 2025, 1:30 - 2:30 PM

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PhD Dissertation Defense - Environmental Science & Policy

Nov 5, 2025, 12:30 - 1:30 PM

Hybrid: Merten Hall, Room 1204 and Virtual on Zoom
Register to join this meeting on Zoom: https://tinyurl.com/573k4mhk

PhD Dissertation
Department of Environmental Science and Policy
College of Science
George Mason University

 

Candidate: Elizabeth S. Collins
Defense Date and Time: Wednesday, November 5, 2025, 12:30-1:30 pm
Defense Location: Merten Hall, Room 1204 and Virtual on Zoom
Title: Using Phylogeography of Palo Santo Trees (Bursera graveolens; Burseraceae) to Reveal Evolutionary Patterns in the Seasonally Dry Tropical Forest Biome

Dissertation Director: Dr. Andrea Weeks
Committee: Drs. James D. Lawrey, Patrick M. Gillevet, and Matthew B. Hamilton

 

ABSTRACT

 

Seasonally dry tropical forests (SDTF) are hypothesized to be dispersal-limited because of their fragmented distribution, ecological stability, and prolonged dry season. This dissertation uses the widespread SDTF tree Bursera graveolens (palo santo) to investigate diversification and population structure through phylogenomic, taxonomic, and population genomic analyses. Results reveal that B. graveolens is monophyletic from Central America southward, while Mexican populations represent two new species. Population genomic analyses support a hypothesis of rare colonization events followed by long-term isolation and drift. This research clarifies the evolutionary history and taxonomy of B. graveolens, offering insights into the evolution of the threatened SDTF biome.

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