Document Type
Poster
Publication Title
Northrop Grumman Engineering & Science Student Design Showcase
Abstract
Scalloped hammerheads (Sphyrna lewini) are a globally endangered species whose life history traits make them vulnerable to fishing pressure1,2. Conservation of the species has been complicated by the discovery of the cryptic Carolina hammerhead (Sphyrna gilberti), which overlaps in range and closely resembles S. lewini3. The only consistent morphological difference, vertebrae count, is lethal to assess (Figures 1 & 2). Few studies have jointly assessed S. gilberti and S. lewini populations, and only one has previously investigated potential hybridization4. This study is the first to develop a method for determining hybridization using a combination of the nuclear gene ITS2 and the mitochondrial control region (mtDNA). Because mtDNA is maternally inherited and nuclear DNA is inherited from both parents, a mismatch between them, known as mitonuclear discordance, can reveal hybridization (Figure 4). If the mtDNA indicates one species while the nuclear DNA indicates another, it suggests the individual had parents of different species and is therefore a hybrid. These tools provide an accessible, nonlethal method for detecting hybridization in cryptic elasmobranchs (sharks, skates, and rays), which is crucial for informing effective conservation strategies.
Advisor
Toby Daly-Engel
Publication Date
4-25-2025
Recommended Citation
Stein, Kieran; Schweppe, Rachel; Hesterhagen, Abby; and Gargiulo, Michelle, "Hidden Hammerheads: Discovering Genetic Markers of Differentiation and Hybridization in Cryptic Shark Species" (2025). Ocean Engineering and Marine Sciences Student Publications. 62.
https://repository.fit.edu/oems_student/62
