Meeting Abstract

P3-107    High sugar diets in the lab and in nature lead to diabetic-like responses in captive green and free-living rock iguanas French, SS*; DeNardo, DF; Knapp, CR; Iverson, JB; Smith, GD; Virgin, EE; Lewis, EL; Webb, AC; Utah State University; Arizona State University; Shedd Aquarium; Earlham College; Dixies State University; Utah State University; Utah State University; Utah State University susannah.french@usu.edu

Chronic high-sugar diets in humans can compromise physiological functions and lead to a range of diseases including diabetes, but such phenomena are less common free-living non-human vertebrates. However, the introduction of supplemental feeding by the tourism industry is becoming increasingly common and can introduce unnatural diets to wildlife. While there are economic and conservation benefits to wildlife tourism, there are also potential problems. To preserve both wild populations and tourist activities into the future, it is critical to understand the implications of supplemental feeding on wildlife health. To address this, we tested the effects of a high glucose diet on glucose tolerance in a controlled setting using captive juvenile green iguanas (Iguana iguana). In the field, we performed glucose tolerance tests on rock iguanas (Cyclura cychlura) that are either fed or unfed by tourists, and we evaluated both acute and chronic blood glucose responses as well as plasma corticosterone concentrations. We found effects of both glucose supplementation in the lab and tourist feeding in the wild on glucose metabolism. In all instances where iguanas received a sugar-rich diet, we found greater acute increases in blood glucose following a glucose challenge. In the wild, tourist-fed iguanas, relative to unfed iguanas, had significantly lower baseline corticosterone levels, higher baseline blood glucose levels, and slower returns to baseline glucose levels following a glucose challenge. Therefore, prediabetic-like responses to unnatural glucose consumption are manifesting in both laboratory animals with relatively short-term glucose treatment and free-living iguanas exposed to long-term supplemental feeding by tourists. We also found more rapid increases in corticosterone in tourist-fed iguanas. More research is needed to understand how dietary changes affect glucose metabolism in non-human systems, as this has important conservation implications.