Molecular Ecology Laboratory, College of Science and Engineering, Flinders University, Adelaide, SA, 5042, Australia.
Centre for Applied Water Science, Institute for Applied Ecology, University of Canberra, Canberra, ACT, 2601, Australia.
Heredity (Edinb). 2023 Jun;130(6):368-380. doi: 10.1038/s41437-023-00612-x. Epub 2023 Mar 30.
To conserve the high functional and genetic variation in hotspots such as tropical rainforests, it is essential to understand the forces driving and maintaining biodiversity. We asked to what extent environmental gradients and terrain structure affect morphological and genomic variation across the wet tropical distribution of an Australian rainbowfish, Melanotaenia splendida splendida. We used an integrative riverscape genomics and morphometrics framework to assess the influence of these factors on both putative adaptive and non-adaptive spatial divergence. We found that neutral genetic population structure was largely explainable by restricted gene flow among drainages. However, environmental associations revealed that ecological variables had a similar power to explain overall genetic variation, and greater power to explain body shape variation, than the included neutral covariables. Hydrological and thermal variables were the strongest environmental predictors and were correlated with traits previously linked to heritable habitat-associated dimorphism in rainbowfishes. In addition, climate-associated genetic variation was significantly associated with morphology, supporting heritability of shape variation. These results support the inference of evolved functional differences among localities, and the importance of hydroclimate in early stages of diversification. We expect that substantial evolutionary responses will be required in tropical rainforest endemics to mitigate local fitness losses due to changing climates.
为了保护热带雨林等热点地区的高功能和遗传多样性，了解驱动和维持生物多样性的力量至关重要。我们研究了环境梯度和地形结构在多大程度上影响了澳大利亚彩虹鱼（Melanotaenia splendida splendida）在湿润热带地区的形态和基因组变异。我们采用了综合河流景观基因组学和形态计量学框架，以评估这些因素对假定适应性和非适应性空间分化的影响。我们发现，中性遗传种群结构在很大程度上可以通过流域间的限制基因流动来解释。然而，环境关联表明，生态变量具有与包括中性协变量相似的解释总体遗传变异的能力，并且比后者更能解释身体形状的变异。水文学和热学变量是最强的环境预测因子，与先前与彩虹鱼的遗传相关的栖息地相关二态性相关的特征相关。此外，与气候相关的遗传变异与形态显著相关，支持了形态变异的可遗传性。这些结果支持了在不同地点存在进化功能差异的推断，以及水气候在多样化早期阶段的重要性。我们预计，热带雨林特有种需要发生重大的进化反应，以减轻由于气候变化而导致的局部适应不良。
