Meeting Abstract
Species ranges are shifting to track thermal or precipitation regimes in response to global climate change. For species with large distributions that contain a broad range of abiotic conditions, responses to novel abiotic conditions of newly colonized areas may be dependent on the adaptation and acclimatization to the environment of the source population’s location. Differential population responses have been shown to reduce performance on the leading edge of ranges of invertebrates by reducing the effectiveness of local adaptations, although similar research in endothermic vertebrates is lacking. Montane habitats provide a natural experimental framework because species with wide elevational ranges experience systematic changes in temperature and oxygen. In this experiment, we collected Anna’s Hummingbirds (Calypte anna) from three different elevations across their elevational range: 0 meters above sea level (asl), 1000 meters asl, and 2500 meters asl. We performed two metabolic tests to examine aerobic performance and thermal tolerance, hovering metabolic rate and torpor use and efficiency, respectively. We performed these tests at the middle of the species elevational range to understand metabolic efficiency inside of the range. We subsequently performed these tests again at 3500 meters asl, 1000 meters above their elevational range limit, to test how the source populations respond to novel temperature and oxygen regimes. We collected dry mass of heart, lungs, liver, and intestinal tract to account for aerobic performance. This study will provide information on whether populations along the elevational gradient will react differently to elevational range shifts associated with global climate change, providing a step forward to mechanistically testing limits of a species ability to respond to global climate change.
