Mechanisms of Seasonal Phenotypic Flexibility in Passerine Birds

University Of South Dakota Main Campus, Vermillion SD

Investigators

Abstract

Small birds adjust their physiology to cope with seasonal periods of high energy demands, but the cellular and molecular mechanisms underlying these adjustments are poorly understood. One example of a period of high energy demand is cold winter climates, which promote increases in heat production capacity and cold tolerance in small birds, and this model forms the focus of this study. In this project, two prominent adjustments of small birds to seasonal periods of high energy demand will be investigated. An increase in the size of the flight muscles, which is associated with an increase the capacity for shivering heat production, and an increase in the capacity for muscles to use fat as fuel, are regulated at the cellular and molecular levels. Biochemical and molecular approaches will be used to characterize adjustments in key potential regulatory points in pathways controlling muscle growth and fat use. These studies will focus on myostatin, a prominent regulator of muscle size in mammals and birds, and proteins involved in transporting fat into and within the muscle cell. Changes in the levels of myostatin and fat transporters will be correlated with periods of high energy demand and elevated capacities for muscular heat production. These experiments will also distinguish the relative roles of temperature and day-length in driving seasonal adjustments in muscle size and fat use. These studies will markedly improve understanding of: (1) the physiological mechanisms by which small birds respond to seasonal changes in energy demand; (2) how environmental cues function as signals for physiological adjustments; and (3) the capacity of small birds, and animals in general, to adjust physiology in response to changing climates. The project will provide research opportunities and training for a postdoctoral fellow, a Ph.D. student, and several undergraduate students. Plans are in place to recruit Native American students to participate in the project.