Population genetics of a climate-indicating predator across the forest-tundra ecotone

阿拉斯加的亚北极淡水湖泊和池塘是极地生物多样性的重要绿洲和北极人民的资源。然而，这个栖息地也是最敏感的干扰，如重金属污染，富营养化，排水或气候变暖造成的干燥。淡水中的环境指示物种既可以作为持续变化的哨兵，也可以作为历史变化的代理。例如，幻影蠓（Chaoborus）是水生毒理学和指示寒带气候的最重要的淡水双翅目昆虫之一。在某些情况下，Chaoborus被认为是一个更好的哨兵北方森林冻土带边界的变化比树线，因为树木可以有一个生长滞后，是可以忽略不计的蠓。Chaoborus的幼虫也是微型甲壳类的贪婪捕食者，因此，可以强烈影响淡水栖息地的物种组成。PI最近发现，在阿拉斯加西北部苏厄德半岛的路边池塘中，有两种Chaoborus在树木线之外很常见。这一发现提供了一个机会，以提高了解如何苔原湖泊和池塘可能会改变，因为他们遇到了一个关键的捕食者的寒带。此外，直接人为干扰，如道路建设对淡水的北方地区？在北美亚北极地区，Chaoborus的生物学的几个方面知之甚少。由于苔原物种和研究充分的温带物种之间存在轻微的形态差异，苔原种群的地理来源甚至物种名称都不清楚。这项研究的目的之一是测试目前在冻土带上发现的关于Chaoborus遗传亲和力的假设。这包括苔原标本与东亚标本和阿拉斯加北部标本的系统发育比较。另一个目标是检验这样一个假设，即道路建设促进了北方地带Chaoborus向冻土带深处的扩张。测试这一假设涉及测试的侵蚀苔原池塘相比，森林池塘的高分辨率遗传标记的遗传多样性。该项目还将对冻原池塘的定居率和方式进行古生态评估。这项研究将使环境生物学家、渔业管理人员、工程师和规划人员了解人类干扰在关键时刻对冻土带-北方森林边界淡水生态系统的作用。该项目将加强或甚至使环境指示chaoborids的比较研究，并促进更深入地了解最近和正在进行的人为变化在亚北极淡水。潮波蠓在冻原池塘定殖的速度和方式对古生态学有重要意义，但尚不清楚。

Subarctic freshwater lakes and ponds in Alaska are important oases for polar biodiversity and resources for arctic peoples. However, this habitat is also among the most sensitive to disturbances such as heavy metal pollution, eutrophication, and drainage or desiccation from climate warming. Environmental indicator species in freshwater have both acted as sentinels for ongoing change and as proxies for historical change. Phantom midges (Chaoborus), for example, are among the most important freshwater dipterans for aquatic toxicology and for indicating a boreal zone climate. In some cases, Chaoborus is believed to be a better sentinel of boreal forest-tundra boundary changes than the tree line because trees can have a growth lag that is negligible in midges. The larvae of Chaoborus are also voracious predators of microcrustaceans and, as such, can strongly affect the species compositions of freshwater habitats. The PI has recently found that two species of Chaoborus are common well beyond the tree line in roadside ponds of the Seward Peninsula of northwestern Alaska. This finding provides an opportunity to improve understanding of how tundra lakes and ponds may change as they encounter a keystone predator of the boreal zone. Moreover, the effect of direct human disturbances such as road construction on the freshwaters of the boreal zone ? tundra boundary can be assessed.Several aspects of the biology of Chaoborus in subarctic North America are poorly known. Because there are slight morphological differences between tundra species and well-studied temperate species, the geographic source and even the species name of the tundra populations are unclear. One objective of this research is to test hypotheses about the genetic affinities of Chaoborus that are presently found on the tundra. This involves phylogenetic comparisons of tundra specimens with those from eastern Asia, and with boreal Alaska. Another goal is to test the hypothesis that road construction has facilitated the expansion of boreal zone Chaoborus deep into the tundra. Testing this hypothesis involves testing for the erosion of genetic diversity on tundra ponds compared to forest ponds with high-resolution genetic markers. This project will also carry out paleoecological assessments of the rate and mode of colonization of tundra ponds. This research will inform environmental biologists, fisheries managers, engineers and planners about the role of human disturbance on the freshwater ecosystems across the tundra-boreal forest boundary at a critical time. The project will enhance or even enable comparative studies of environment-indicating chaoborids and promote a deeper understanding of recent and ongoing anthropogenic change in subarctic freshwaters. The speed and mode of colonization of tundra ponds by Chaoborus midges is important to paleoecology but unknown.