景观一直承受着人类引起的生态变化的压力,经常导致物种分布的变化。对于一些物种来说,改变他们的生态位空间的地理宽度导致匹配范围转移到除了他们被正式发现的区域之外的区域。在这项研究中,我们采用人口基因组学方法来评估可能的保护问题,这些问题是由于据称范围扩展到德克萨斯州南部的两个姊妹种鸭子:斑驳(Anasfulligula)和墨西哥(Anasdiazi)鸭子。具体来说,尽管不是移民,这两个物种越来越多地被记录在它们的正式范围之外,墨西哥和斑驳的鸭子向东北和向西扩张,分别,也许会导致今天的二次接触。我们使用这两个物种范围内的数千个常染色体基因座评估了遗传祖先,以及来自德克萨斯州南部重叠地区的墨西哥和斑驳的鸭子样本。首先,我们确认这两个物种确实在扩大它们的范围,与遗传纯的西部墨西哥湾沿岸斑驳的鸭子确认西部到拉萨尔县,德州,而墨西哥鸭子记录在美国-墨西哥边境附近的德克萨斯州各县。重要的是,在这些地区之间发现了第一个确认的墨西哥×斑驳的鸭杂种,这可能代表了一个最近建立的接触区,平均而言,~100公里宽。我们假设气候和土地利用相关的变化,包括沿海栖息地的退化以及德克萨斯州内陆地区人工栖息地的增加,正在促进这些范围扩展。因此,继续监测最近的接触事件可以帮助了解人类世的物种反应,但它也可以用来修改斑鸭的业务调查区域。
Landscapes are consistently under pressure from human-induced ecological change, often resulting in shifting species distributions. For some species, changing the geographical breadth of their niche space results in matching range shifts to regions other than those in which they are formally found. In this study, we employ a population genomics approach to assess potential conservation issues arising from purported range expansions into the south Texas Brush Country of two sister species of ducks: mottled (Anas fulvigula) and Mexican (Anas diazi) ducks. Specifically, despite being non-migratory, both species are increasingly being recorded outside their formal ranges, with the northeastward and westward expansions of Mexican and mottled ducks, respectively, perhaps resulting in secondary contact today. We assessed genetic ancestry using thousands of autosomal loci across the ranges of both species, as well as sampled Mexican- and mottled-like ducks from across overlapping regions of south Texas. First, we confirm that both species are indeed expanding their ranges, with genetically pure Western Gulf Coast mottled ducks confirmed as far west as La Salle county, Texas, while Mexican ducks recorded across Texas counties near the USA-Mexico border. Importantly, the first confirmed Mexican × mottled duck hybrids were found in between these regions, which likely represents a recently established contact zone that is, on average, ~100 km wide. We posit that climate- and land use-associated changes, including coastal habitat degradation coupled with increases in artificial habitats in the interior regions of Texas, are facilitating these range expansions. Consequently, continued monitoring of this recent contact event can serve to understand species\' responses in the Anthropocene, but it can also be used to revise operational survey areas for mottled ducks.