Flathead Lake Biological Station, University of Montana, 32125 Bio Station Lane, Polson, MT, USA.
US Geological Survey, Northern Rocky Mountain Science Center, Glacier National Park, West Glacier, MT, USA.
J Hered. 2022 Jul 23;113(4):453-471. doi: 10.1093/jhered/esac025.
Understanding how environmental variation influences population genetic structure can help predict how environmental change influences population connectivity, genetic diversity, and evolutionary potential. We used riverscape genomics modeling to investigate how climatic and habitat variables relate to patterns of genetic variation in 2 stonefly species, one from mainstem river habitats (Sweltsa coloradensis) and one from tributaries (Sweltsa fidelis) in 40 sites in northwest Montana, USA. We produced a draft genome assembly for S. coloradensis (N50 = 0.251 Mbp, BUSCO > 95% using "insecta_ob9" reference genes). We genotyped 1930 SNPs in 372 individuals for S. coloradensis and 520 SNPs in 153 individuals for S. fidelis. We found higher genetic diversity for S. coloradensis compared to S. fidelis, but nearly identical genetic differentiation among sites within each species (both had global loci median FST = 0.000), despite differences in stream network location. For landscape genomics and testing for selection, we produced a less stringently filtered data set (3454 and 1070 SNPs for S. coloradensis and S. fidelis, respectively). Environmental variables (mean summer precipitation, slope, aspect, mean June stream temperature, land cover type) were correlated with 19 putative adaptive loci for S. coloradensis, but there was only one putative adaptive locus for S. fidelis (correlated with aspect). Interestingly, we also detected potential hybridization between multiple Sweltsa species which has never been previously detected. Studies like ours, that test for adaptive variation in multiple related species are needed to help assess landscape connectivity and the vulnerability of populations and communities to environmental change.
了解环境变异如何影响种群遗传结构，可以帮助预测环境变化如何影响种群连通性、遗传多样性和进化潜力。我们使用河流景观基因组学模型来研究气候和生境变量如何与美国蒙大拿州西北部 40 个地点的两种石蝇物种（一种来自干流生境的 Sweltsa coloradensis，另一种来自支流的 Sweltsa fidelis）的遗传变异模式相关。我们为 S. coloradensis 生成了一个基因组草图组装（N50=0.251 Mbp，使用“insecta_ob9”参考基因时 BUSCO>95%）。我们对 372 个 S. coloradensis 个体进行了 1930 个 SNP 基因分型，对 153 个 S. fidelis 个体进行了 520 个 SNP 基因分型。我们发现 S. coloradensis 的遗传多样性高于 S. fidelis，但每个物种内的站点之间几乎没有遗传分化（两者的全球位点中位数 FST=0.000），尽管溪流网络位置不同。对于景观基因组学和选择测试，我们生成了一个过滤不太严格的数据集（S. coloradensis 和 S. fidelis 分别有 3454 个和 1070 个 SNP）。环境变量（夏季平均降水量、坡度、方位、六月平均溪流温度、土地覆盖类型）与 S. coloradensis 的 19 个假定适应性基因座相关，但 S. fidelis 只有一个假定适应性基因座（与方位相关）。有趣的是，我们还检测到多个 Sweltsa 物种之间存在潜在的杂交，这是以前从未检测到的。像我们这样的研究，测试多个相关物种的适应性变异，对于帮助评估景观连通性以及种群和群落对环境变化的脆弱性是必要的。
