Current Research and Research Interests

M.S. Thesis:

Global population structure of the tope shark (Galeorhinus galeus) as inferred by mitochondrial control region sequence data

Thesis Defended : May 11, 2007

Abstract - Joint Meeting of Ichthyologists and Herpetologists, St. Louis, MO, July 2007

Global Population Structure Of The Tope (Galeorhinus galeus), As Inferred By Mitochondrial Control Region Sequence Data
The tope, Galeorhinus galeus, is a medium sized member of the order Carcharhiniformes (family: Triakidae), currently distributed globally in temperate waters.  Global populations of G. galeus are considered to be in decline due to the exploitation of shark fisheries over the past 80 years.  Little is known of the northeastern Pacific population of G. galeus,and recent observations off the California coast indicate an increase in numbers.  To determine the genetic structure of northeastern Pacific G. galeus populations, and the levels of gene flow among globally distributed populations, samples (n = 96) were collected and analyzed from five geographically dispersed populations (Argentina, Australia, California, South America, and the U.K.).  A 1006-bp section of the 1068-bp mitochondrial control region (mtCR) revealed 33 polymorphic sites with 20 transitions, 11 transversions, and 2 deletions producing 28 haplotypes.  Haplotypes were unique to their geographic location with only one haplotype shared between Africa and Australia.  Overall, populations demonstrated high levels of haplotype diversity (0.9004 +/- 0.0172), low levels of nucleotide diversity (0.0065520 +/- 0.003458), and significant genetic structure (FST = 0.27151 and ΦST =0.85642; P < 0.001).  Based on the results of this study, increasing numbers of G. galeus in the northeastern Pacific can be best explained by local recruitment and not input from geographically distant populations.