Rosenthal William C, Mandeville Elizabeth G, Pilkerton Ashleigh M, Gerrity Paul C, Skorupski Joseph A, Walters Annika W, Wagner Catherine E
Department of Botany University of Wyoming Laramie Wyoming USA.
Program in Ecology University of Wyoming Laramie Wyoming USA.
Ecol Evol. 2024 Jul 21;14(7):e11706. doi: 10.1002/ece3.11706. eCollection 2024 Jul.
Dams have negatively affected freshwater biodiversity throughout the world. These negative effects tend to be exacerbated for aquatic taxa with migratory life histories, and for taxa whose habitat is fundamentally altered by the formation of large reservoirs. Sauger (; Percidae), large-bodied migratory fishes native to North America, have seen population declines over much of the species' range, and dams are often implicated for their role in blocking access to spawning habitat and otherwise negatively affecting river habitat. Furthermore, hybridization appears to be more frequent between sauger and walleye in the reservoirs formed by large dams. In this study, we examine the role of dams in altering sauger population connectivity and facilitating hybridization with introduced walleye in Wyoming's Wind River and Bighorn River systems. We collected genomic data from individuals sampled over a large spatial scale and replicated sampling throughout the spawning season, with the intent to capture potential variation in hybridization prevalence or genomic divergence between sauger with different life histories. The timing of sampling was not related to hybridization prevalence or population divergence, suggesting limited genetic differences between sauger spawning in different time and places. Overall, there was limited hybridization detected, however, hybridization was most prevalent in Boysen Reservoir (a large impounded section of the Wind River). Dams in the lower Wind River and upper Bighorn River were associated with population divergence between sauger upstream and downstream of the dams, and demographic models suggest that this divergence has occurred in concordance with the construction of the dam. Sauger upstream of the dams exhibited substantially lower estimates of genetic diversity, which implies that disrupted connectivity between Wind River and Bighorn River sauger populations may already be causing negative demographic effects. This research points towards the importance of considering the evolutionary consequences of dams on fish populations in addition to the threats they pose to population persistence.
水坝对全球淡水生物多样性产生了负面影响。对于具有洄游生活史的水生类群，以及栖息地因大型水库形成而发生根本性改变的类群而言，这些负面影响往往会加剧。北美原产的大型洄游鱼类——鼓眼鱼（鲈科），在其大部分分布范围内数量都有所下降，水坝常常被认为在阻碍其进入产卵栖息地以及对河流栖息地产生其他负面影响方面起到了作用。此外，在大型水坝形成的水库中，鼓眼鱼和大眼狮鲈之间的杂交似乎更为频繁。在本研究中，我们探究了水坝在改变鼓眼鱼种群连通性以及促进其与引入的大眼狮鲈在怀俄明州风河和大角河系统中杂交方面所起的作用。我们从在大空间尺度上采样的个体收集了基因组数据，并在整个产卵季节重复采样，目的是捕捉不同生活史的鼓眼鱼在杂交发生率或基因组差异方面的潜在变化。采样时间与杂交发生率或种群差异无关，这表明在不同时间和地点产卵的鼓眼鱼之间遗传差异有限。总体而言，检测到的杂交情况有限，然而，杂交在博伊森水库（风河的一个大型蓄水区域）最为普遍。风河下游和大角河上游的水坝与水坝上下游鼓眼鱼的种群差异有关，人口统计学模型表明这种差异与水坝的建设一致。水坝上游的鼓眼鱼遗传多样性估计值显著较低，这意味着风河和大角河鼓眼鱼种群之间连通性的破坏可能已经在造成负面的人口统计学影响。这项研究指出，除了水坝对种群持续性构成的威胁外，考虑其对鱼类种群的进化后果也很重要。
