The Rio Grande drainage of the southwestern United States and Mexico has undergone intense anthropogenic alteration by water diversions, extraction and associated habitat changes. These alterations have disproportionately impacted the pelagic broadcast spawning guild of minnows (pelagophils). Several Rio Grande endemic pelagophils, including the co-occurring Rio Grande Shiner (Notropis jemezanus) and Speckled Chub (Macrhybopsis aestivalis), have experienced dramatic recent range-wide declines yet have slipped under the radar of conservation efforts. The status of N. jemezanus and M. aestivalis in the Rio Grande and Pecos River was evaluated and standing genetic variation was characterized. Genetic evidence indicates that populations of both species found in the Rio Grande and Pecos River are genetically distinct. Additionally, 159 outlier loci were identified in M. aestivalis suggesting possible local adaptation in the Rio Grande and Pecos River populations. Though range-wide genetic data are limited, N. jemezanus populations in both rivers harbor considerable genetic diversity. Mitochondrial data from both taxa are consistent with a history of secondary contact between formerly isolated populations with deeply divergent haplotypes found within the Rio Grande and Pecos River populations of N. jemezanus and within the Rio Grande population of M. aestivalis. Extensive survey efforts in the lower Rio Grande and its tributaries in Texas document significant range contraction and near extirpation of N. jemezanus from this part of the basin; highlighting the need for immediate action to protect the species.

美国西南部和墨西哥的里约格兰德河的排水因引水，抽水和相关生境变化而遭受了强烈的人为改变。这些变化不成比例地影响了小鱼（中飞鱼）的中上层繁殖产卵行会。几个同时出现的里约格兰德特产嗜血杆菌，包括同时出现的里奥格兰德希纳（Notropis jemezanus）和斑点斑点（Macrhybopsis aestivalis），最近在整个范围内都出现了急剧下降，但在保护工作的关注下却有所下滑。的状态N. jemezanus和M. aestivalis在里奥格兰德河和佩科斯河上进行了评估，并对站立的遗传变异进行了表征。遗传证据表明，在里奥格兰德和佩科斯河发现的这两种物种的种群在遗传上是不同的。此外，在印度洋分枝杆菌中发现了159个异常基因座，表明在里奥格兰德河和佩科斯河河口种群中可能存在局部适应。尽管范围广泛的遗传数据有限，但两条河流中的红叶猪笼草种群具有相当大的遗传多样性。来自这两个类群的线粒体数据与以前分离的种群之间的二次接触历史一致，该种群在里约格兰德河和佩科斯河的N. jemezanus种群和里约热内卢的种群内发现了高度不同的单倍型。M. aestivalis。在得克萨斯州里奥格兰德河及其支流的广泛调查工作表明，从盆地的这一部分来看，jemezanus猪大范围收缩和几乎灭绝。强调需要立即采取行动保护该物种。