Molecular Ecology Laboratory, College of Science and Engineering, Flinders University, Adelaide, SA, 5001, Australia.
Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
Evolution. 2022 Jan;76(1):171-183. doi: 10.1111/evo.14399. Epub 2021 Dec 2.
How populations of aquatic fauna persist in extreme desert environments is an enigma. Individuals often breed and disperse during favorable conditions. Theory predicts that adaptive capacity should be low in small populations, such as in desert fishes. We integrated satellite-derived surface water data and population genomic diversity from 20,294 single-nucleotide polymorphisms across 344 individuals to understand metapopulation persistence of the desert rainbowfish (Melanotaenia splendida tatei) in central Australia. Desert rainbowfish showed very small effective population sizes, especially at peripheral populations, and low connectivity between river catchments. Yet, there was no evidence of population-level inbreeding and a signal of possible adaptive divergence associated with aridity was detected. Candidate genes for local adaptation included functions related to environmental cues and stressful conditions. Eco-evolutionary modeling showed that positive selection in refugial subpopulations combined with connectivity during flood periods can enable retention of adaptive diversity. Our study suggests that adaptive variation can be maintained in small populations and integrate with neutral metapopulation processes to allow persistence in the desert.
水生动物种群如何在极端沙漠环境中生存是一个谜。个体通常在有利条件下繁殖和扩散。理论预测，小种群（如沙漠鱼类）的适应能力应该较低。我们整合了卫星衍生的地表水数据和来自 344 个个体的 20,294 个单核苷酸多态性的群体基因组多样性，以了解澳大利亚中部沙漠彩虹鱼（Melanotaenia splendida tatei）的复合种群持久性。沙漠彩虹鱼表现出非常小的有效种群大小，尤其是在边缘种群中，并且河流流域之间的连通性较低。然而，没有证据表明存在群体水平的近交，并且检测到与干旱相关的可能适应性分歧的信号。适应局部环境的候选基因包括与环境线索和应激条件相关的功能。生态进化模型表明，避难所亚种群中的正选择与洪水期间的连通性相结合，可以保持适应性多样性。我们的研究表明，适应变异可以在小种群中维持，并与中性复合种群过程相结合，从而使沙漠得以生存。
