Program Man-Society-Environment, University of Basel Basel, Switzerland.
Limnological Institute, University of Konstanz Konstanz, Germany.
Evol Appl. 2013 Dec;6(8):1119-32. doi: 10.1111/eva.12087. Epub 2013 Sep 10.
Human-induced nutrient input can change the selection regime and lead to the loss of biodiversity. For example, eutrophication caused speciation reversal in polymorphic whitefish populations through a flattening of littoral-pelagic selection gradients. We investigated the current state of phenotypic and genetic diversity in whitefish (Coregonus macrophthalmus) in a newly restored lake whose nutrient load has returned to pre-eutrophication levels and found that whitefish spawning at different depths varied phenotypically and genetically: individuals spawning at shallower depth had fewer gill rakers, faster growth, and a morphology adapted to benthic feeding, and they showed higher degrees of diet specialization than deeper spawning individuals. Microsatellite analyses complemented the phenotype analyses by demonstrating reproductive isolation along different spawning depths. Our results indicate that whitefish still retain or currently regain phenotypic and genetic diversity, which was lost during eutrophication. Hence, the population documented here has a potential for future divergence because natural selection can target phenotypes specialized along re-established littoral-pelagic selection gradients. The biodiversity, however, will have better chances to return if managers acknowledge the evolutionary potential within the local whitefish and adapt fishing and stocking measures.
人为的营养输入可以改变选择机制，导致生物多样性的丧失。例如，富营养化通过平坦化沿岸-层化选择梯度，导致多态白鲑种群的物种形成逆转。我们研究了一个新恢复的湖泊中白鲑（Coregonus macrophthalmus）的表型和遗传多样性的现状，该湖泊的营养负荷已恢复到富营养化前的水平，发现不同深度产卵的白鲑在表型和遗传上存在差异：在较浅深度产卵的个体具有较少的鳃耙、更快的生长速度和适应底栖摄食的形态，并且它们比在较深深度产卵的个体表现出更高的饮食特化程度。微卫星分析通过证明不同产卵深度的生殖隔离补充了表型分析。我们的结果表明，白鲑仍然保留或正在恢复富营养化期间丧失的表型和遗传多样性。因此，这里记录的种群具有未来分化的潜力，因为自然选择可以针对重新建立的沿岸-层化选择梯度特化的表型。然而，如果管理者承认当地白鲑的进化潜力，并调整捕捞和放养措施，生物多样性将有更好的机会恢复。
