Meeting Abstract

26.2  Monday, Jan. 4  Evolutionary variation in physiological traits contributes to differences in swimming capacity among migratory and non-migratory threespine stickleback (Gasterosteus aculeatus). DALZIEL, AC*; SCHULTE, PM; University of British Columbia; University of British Columbia dalziel@zoology.ubc.ca

The threespine stickleback species group contains a number of unique ecotypes, including migratory and non-migratory (stream-resident) populations. The migratory and stream-resident ecotypes show heritable differences in endurance swimming capacity that have evolved in parallel in multiple populations along the coast of British Columbia, suggesting that natural selection has played a role in shaping these differences in performance. To determine which underlying traits may contribute to these differences in swimming performance, and if they too have evolved in parallel, we conducted a common garden experiment using progeny from parental fish collected from two different locations. We raised the progeny of pure stream-resident, pure migratory, and reciprocal F1 hybrid crosses in the lab and tested these fish for differences in swimming performance and underlying physiological and biochemical traits. We have found that migratory sticklebacks, and F1 hybrids that swim as well as pure migratory fish, can achieve significantly higher maximal metabolic rates and have larger pectoral muscles and pectoral fins than do stream-resident fish and F1 hybrids that are poor swimmers. We will present data that further examines the physiological and biochemical properties of the swimming musculature (i.e. muscle size, fiber-type composition, enzyme capacities), and other steps in the oxygen transport cascade (i.e. gill surface area, heart size) to determine which traits are necessary for superior endurance swimming performance.