Meeting Abstract
Locomotor performance is dictated by a complex array of interacting phenotypic features. In swimming fish these include the physiological properties of muscular power sources and the form of propulsors and drag inducing structures. Where distinct modes of locomotion are employed by the same organism, the overlap between the phenotypic features associated with each mode dictates whether performance in these modes is linked. Bluegill sunfish (Lepomis macrochirus) have two swimming modes: pectoral fin power labriform at low speeds; body-caudal fin (BCF) at high speeds. Our goal was to develop an integrated understanding of how phenotype dictates swimming performance in bluegill sunfish. If labriform and BCF swimming are associated with separate groups of phenotypic features, then performance in each mode should be decoupled from the other and associated with distinct aspects of phenotype. Maximal swimming speeds were established during flume swimming. The contractile properties and the activity of metabolic enzymes (citrate synthase and lactate dehydrogenase) in the pectoral and myotomal muscles were measured along with detailed morphological and anatomical data. Labriform and BCF swimming performance were not decoupled, maximum speeds in both modes were correlated. Each mode was however associated with largely separate sets of phenotypic features. Muscle masses, power outputs and metabolic enzyme activities were generally more important determinants of performance than external morphology. Identifying the phenotypic features that most strongly predict performance is an important step in establishing predictive links between phenotypic and performance variation.
