S5-1.5 Thursday, Jan. 5 Perspectives on salt gland evolution in marine snakes BABONIS, L.S.*; BRISCHOUX, F.; Univ of Hawaii/Kewalo Marine Laboratory; CEBC-CNRS, 79360 Villiers en Bois, France email@example.com
Throughout the evolution of vertebrates, invasion of desiccating environments (e.g., marine and desert environments) has occurred numerous times. Because most vertebrates maintain dilute body fluids, the invasion of these desiccating environments was likely associated with the development of physiological features that permit the maintenance of low plasma osmolality. The diversity of specialized salt-secreting glands across vertebrate lineages suggests that this tissue has evolved numerous times, independently, throughout the evolution of vertebrates. Though the form and function of vertebrate salt glands have been studied for decades, there have been few hypotheses regarding the potential mechanisms that led to the convergent evolution of these glands across taxa. Here, we review the distribution of salt glands across tetrapod taxa to develop hypotheses about the number of convergent events that must have occurred to give rise to the modern diversity of these glands in marine taxa. Further, we review the anatomy and physiology of these specialized glands in comparison with glands that are not specialized for salt-secretion, using marine snakes as a model. Finally, we use these comparative data to propose potential mechanisms by which salt glands may have evolved independently from the repeated co-option of unspecialized precursors.