Birds that naturally encounter high carbon dioxide, low oxygen environments as a consequence of nesting in underground tunnels or cavities, show blunted ventilatory responsiveness to carbon dioxide. The altered thresholds and sensitivities of burrow-dwelling birds clearly indicate that the set-point for their ventilation is different from that of nonburrowers. It is not known if the bluntered responsiveness of these birds to carbon dioxide is a genetically determined and selected trait or if it is a phenotypic characteristic that can be ontogenetically determined by the environment during development. The proposed research addresses this fundamental question of what establishes ventilatory set-points (i.e., are they inherited or acquired). In answering this question, the PI will experimentally manipulate the gaseous environments during embryonic and post-embryonic development of a burrower to determine if either treatment, or both, effects adult ventilatory set-points. A parallel set of experiments will be conducted with a nonburrowing bird. The proposed project will significantly contribute to our understanding of respiratory control in birds, which is to date very incomplete.
