Data from: Convergence in organ size but not energy metabolism enzyme activities among wild Lake Whitefish (Coregonus clupeaformis) species pairs

The repeated evolution of similar phenotypes by similar mechanisms can be indicative of local adaptation, constraints or biases in the evolutionary process. Little is known about the incidence of physiological convergence in natural populations, so here we test whether energy metabolism in ‘dwarf’ and ‘normal’ Lake Whitefish evolves by similar mechanisms. Prior genomic and transcriptomic studies have found that divergence in energy metabolism is key to local adaptation in whitefish species pairs, but that distinct genetic and transcriptomic changes often underlie phenotypic evolution among lakes. Here, we predicted that traits at higher levels of biological organization, including the activities of energy metabolism enzymes (the product of enzyme concentration and turnover rate) and the relative proportions of metabolically active tissues (heart, liver, skeletal muscle), would show greater convergence than genetic and transcriptomic variation. We compared four whitefish species pairs and found convergence in organ size whereby all dwarf whitefish populations have a higher proportion of red skeletal muscle, three have relatively larger livers and two have relatively larger ventricles than normal fish. On the other hand, hepatic and muscle enzyme activities showed little convergence and were largely dependent on lake of origin. Only the most genetically divergent species pair (Cliff Lake) displayed white muscle enzyme activities matching results from laboratory-reared normal and dwarf whitefish. Overall, these data show convergence in the evolution of organ size, but not in the activities of candidate enzymes of energy metabolism, which may have evolved mainly as a consequence of demographic or ecological differences among lakes.通过相似演化机制反复产生相似表型的现象，可指示演化过程中存在局部适应、演化限制或演化偏向。目前学界对自然种群中生理趋同的发生情况所知甚少，因此本研究旨在验证‘矮型’与‘正常型’湖白鲑（Lake Whitefish）的能量代谢是否通过相似机制演化。此前的基因组学与转录组学研究已发现，能量代谢分化是白鲑物种对局部环境适应的关键驱动因素，但不同湖泊间的表型演化往往由不同的遗传与转录组变化所介导。本研究预测，相较于遗传与转录组变异，生物组织层级更高的性状——包括能量代谢酶活性（即酶浓度与转换速率的乘积）以及代谢活跃组织（心脏、肝脏、骨骼肌）的相对占比——会表现出更强的趋同性。本研究比对了四组白鲑物种对，发现器官大小存在趋同演化：相较于正常型个体，所有矮型白鲑种群的红色骨骼肌占比更高，其中3个种群的肝脏相对更大，2个种群的心室相对更大。但肝脏与骨骼肌的酶活性几乎未表现出趋同性，且很大程度上取决于其来源湖泊。仅遗传分化程度最高的物种对（克利夫湖，Cliff Lake）的白肌酶活性，与实验室饲养的正常型和矮型白鲑的实验结果相符。综合来看，本研究数据证实了器官大小演化存在趋同性，但能量代谢候选酶活性并未表现出趋同，后者的演化或主要源于不同湖泊间的种群统计或生态差异。