Department of Zoology and Biodiversity Research Center, University of British Columbia, Vancouver, BC, Canada, V6T 1Z4.
J Exp Biol. 2012 Oct 15;215(Pt 20):3587-96. doi: 10.1242/jeb.071951. Epub 2012 Jul 5.
Determining which underlying traits contribute to differences in whole-animal performance can be difficult when many traits differ between individuals with high and low capacities. We have previously found that migratory (anadromous marine) and non-migratory (stream-resident) threespine stickleback (Gasterosteus aculeatus) populations have genetically based differences in prolonged swimming performance (U(crit)) that are associated with divergence of a number of candidate morphological and physiological traits (pectoral fin size and shape, body shape, pectoral muscle and heart size, and pectoral muscle metabolic enzyme activities). Here, we use F2 hybrid crosses to determine which traits are correlated with U(crit) when expressed in a largely randomized genetic background and a range of trait values for other divergent traits. We found that four of our 12 candidate traits were positively correlated with U(crit) in F2 hybrids and that the combined effects of ventricle mass, pectoral adductor mass and adductor citrate synthase activity accounted for 17.9% of the variation in U(crit). These data provide additional support for a causal role of muscle and heart size in mediating intraspecific differences in U(crit), but indicate that many candidate morphological and biochemical traits do not have a strong effect on U(crit) when disassociated from other divergent traits. However, the limited variation in U(crit) in our F2 hybrid families may have decreased our ability to detect correlations among these candidate traits and U(crit). These data suggest that many traits, interactions among traits and traits not measured in this study affect prolonged swimming performance in threespine stickleback.
当许多性状在高能力个体和低能力个体之间存在差异时，确定哪些潜在性状导致了整体动物性能的差异可能会很困难。我们之前发现，洄游（海洋溯河洄游）和非洄游（溪流居留）的三刺鱼（Gasterosteus aculeatus）种群在长时间游泳性能（Ucrit）上存在遗传差异，这些差异与许多候选形态和生理性状的分歧有关（胸鳍大小和形状、体型、胸肌和心脏大小以及胸肌代谢酶活性）。在这里，我们使用 F2 杂种杂交来确定哪些性状在广泛随机遗传背景和一系列其他性状差异的性状值下与 Ucrit 相关。我们发现，我们的 12 个候选性状中有 4 个在 F2 杂种中与 Ucrit 呈正相关，并且心室质量、胸肌收肌质量和收肌柠檬酸合酶活性的综合效应占 Ucrit 变异的 17.9%。这些数据为肌肉和心脏大小在介导 Ucrit 种内差异中的因果作用提供了额外的支持，但表明当与其他性状差异分离时，许多候选形态和生化性状对 Ucrit 没有强烈影响。然而，我们的 F2 杂种系中 Ucrit 的变异有限，这可能降低了我们在这些候选性状和 Ucrit 之间检测相关性的能力。这些数据表明，许多性状、性状之间的相互作用以及本研究未测量的性状都会影响三刺鱼的长时间游泳性能。
