48.3 Thursday, Jan. 5 Comparative metabolic rate and assimilation between an endemic rattlesnake and an invasive boa: implications for invasive species success GOESSLING, J.M.*; LUTTERSCHMIDT, W.I.; REINERT, H.K.; ODUM, R.A.; Sam Houston State University; Sam Houston State University and the Texas Research Institute for Environmental Studies; The College of New Jersey; Toledo Zoological Society email@example.com
Islands are often limited in resource availability and niche space. Thus, islands represent ideal models for studying the ecological relationships between native and invasive species. We investigated a potential mechanism by which invasive species may demonstrate a competitive advantage over native species. We examined the comparative energetics between an endemic rattlesnake (Crotalus durissus unicolor) and an invasive boa (Boa constrictor constrictor) on the island of Aruba. Differences in metabolic rate were tested across three treatments (rest, digestive-lizard, and digestive-mouse) and assimilation efficiency across two treatments (digestive-lizard and digestive-mouse); we also examined relative digestive tract morphology to identify possible correlates with potential energetic differences. We found both an effect of species and treatment on the metabolic rate of snakes (repeated two-way ANOVA: effect of species P < 0.001; effect of treatment P = 0.005), with boas having a lower metabolic rate than rattlesnakes. Using calorimetry, we found that boas have a higher assimilation efficiency than rattlesnakes with both food types (lizard and mouse; two-way ANOVA: P = 0.003). The analysis of relative digestive tract morphology showed no differences between species. Our results suggest that B. c. constrictor may be more energetically conservative than C. d. unicolor and we therefore discuss how physiological efficiency may be a mechanism by which B. c. constrictor has been able to rapidly expand its range and population on Aruba.