Semester of Graduation
Spring 2026
Degree Type
Thesis
Degree Name
Masters in Integrative Biology
Department
Ecology, Evolution, and Organismal Biology
Committee Chair/First Advisor
Nicholas Green
Abstract
American alligators (Alligator mississippiensis) inhabit diverse aquatic ecosystems including freshwater wetlands, swamps, and estuarine rivers. As apex predators, their physiological resilience has implications for ecosystem stability and long-term conservation. With projected sea-level rise and increasing saltwater intrusion into coastal freshwater habitats, understanding the osmoregulatory capacity of alligators is increasingly important. Unlike marine-tolerant crocodilians such as the saltwater crocodile (Crocodylus porosus), which possess specialized salt-secreting lingual glands in addition to renal and cloacal mechanisms, the morphology and physiological significance of lingual glands in wild American alligators remain poorly understood. This study examined lingual gland morphology and plasma ion physiology in four wild American alligator populations exposed to differing salinity regimes (Jekyll Island, Sapelo Island, Okefenokee National Wildlife Refuge, and Banks Lake National Wildlife Refuge). Plasma osmolality and ion concentrations were measured from blood samples, and lingual gland biopsies were analyzed using light microscopy to quantify pore count, gland area, secretory tubule count, tubule density, and tubule lumen area. Coastal alligators did not exhibit elevated plasma osmolality or ion concentrations relative to inland populations. Lingual gland morphology also did not differ significantly between populations, although the relationship between secretory tubule count and body size varied. Comparative analyses across crocodilian species showed that crocodile lingual glands are substantially larger and possess greater tubule lumen area and tubule density than those of American alligators, reinforcing pronounced divergence between alligators and saltwater-tolerant crocodiles.
Included in
Cell Biology Commons, Comparative and Evolutionary Physiology Commons, Evolution Commons, Integrative Biology Commons, Population Biology Commons
Comments
This research was funded using the department of Ecology, Evolution, and Organismal Biology's graduate research funds and the College of Science and Mathematics' Mentor-Protege Program.