Meeting Abstract
P2.178 Saturday, Jan. 5 Comparative study of the oxidative metabolism in skeletal muscle of migratory and nonmigratory White-crowned Sparrows CAMPION, A*; HWEE, D; BAEHR, L; NEMETH, Z; BODINE, S; RAMENOFSKY, M; Univ. of California, Davis; Univ. of California, Davis; Univ. of California, Davis; Univ. of California, Davis; Univ. of California, Davis; Univ. of California, Davis awcampion@ucdavis.edu
The annual cycle of many long distance migrants is characterized by dramatic changes in behavior and physiology or phenotypic flexibility. Such alterations serve to match individuals with the energetic demands of each life history stage. Yet, it is unknown whether traits attributed to migrants are expressed also in nonmigratory congeners. We present data comparing the oxidative capacity of skeletal muscle of the long distance migrant, Zonotrichia leucophrys gambelii with its nonmigratory congener Z.l. nutttalli both within and across their life history stages. Owing to the reliance on efficient energy utilization for migration, we measured enzyme concentration of succinate dehydrogenase and citrate synthase in the flight and gastrocnemius muscles of both subspecies using western blot analysis. We predicted upregulation of enzymes in flight muscle during migration that would be absent in the nonmigrant’s flight muscle and absent in both subspecies’ gastrocnemius muscle. Seasonally, the flight muscle of the two subspecies had elevated enzyme concentrations during both the post breeding and fall stages. Specifically, in the migrant, both enzymes were elevated in flight muscle when birds departed from the breeding grounds in fall but had decreased upon arrival to the wintering site (P<0.05). As predicted, enzyme concentrations in flight muscle of Gambelii exceeded those of Nuttalli during the post breeding and fall stages (P<0.05) but were comparable during winter, a stage when the congeners are most similar. Our results reveal dynamic changes in the oxidative capacity of the flight muscle of Gambelii that contribute to phenotypic flexibility attributed to the migratory life history.
