Using sedaDNA from California Holocene and Anthropocene lake sediments to determine drivers of the “Insect Apocalypse”

昆虫代表了地球上所描述的物种的一半以上，并在生态过程、生态系统功能和人类福祉方面发挥着关键作用。昆虫的减少已被广泛记录在案，这些下降的原因可归因于人类影响，包括气候变化、栖息地丧失和退化、包括杀虫剂在内的农业集约化以及非本土物种的引入。然而，我们还不了解这些因素的相对重要性和协同作用。尽管我们有详细记录全球某些地区昆虫多样性和丰度的最新变化，但较长期的记录(50年)很少见。这些长期记录对于了解昆虫开始大规模下降的时间、进展到什么程度以及昆虫种群最近的变化是否在正常变化范围内都很重要。我们对生物多样性危机的了解也是有限的，因为之前的工作主要集中在某些昆虫群体上，比如传粉者和蝴蝶，而我们对其他群体是否或如何受到影响知之甚少。这项研究将分析加州湖泊沉积物岩心中的昆虫DNA，以重建1200年来昆虫多样性变化的记录。通过使用DNA分析，研究人员将能够研究以前没有受到太多研究关注的昆虫物种。该项目还将收集有关土地使用变化、气候变化和杀虫剂应用的数据，以将这些对人类的影响与随时间推移的昆虫多样性联系起来。这项研究通过提高我们对昆虫衰退的基线理解，并区分上个世纪昆虫多样性的自然变化和人类影响造成的变化，促进了生物多样性的保护。该项目将有助于开发新的研究技术和生物多样性监测技术。该项目将利用从旧金山湾区(美国加利福尼亚州)贾斯珀里奇生物保护区(JRBP)的沼泽和水文连接的水库收集的沉积物岩心。总而言之，这些核心跨越了一段时间内不断增加的局部和全球人类影响。研究人员将使用传统的古生态工具以及新兴的沉积DNA(SedaDNA)技术。为了表征昆虫随时间的多样性，研究人员将使用元数据库编码和高通量测序分析沉积物岩心中的sedaDNA。为了开发昆虫多样性变化的高分辨率记录，研究人员将使用地球化学和微化石分析、sedaDNA和历史记录。这个多代理、高分辨率的数据集将使用几种多变量建模方法进行统计查询。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Insects represent more than half of described species on earth and play critical roles in ecological processes, ecosystem function, and human well-being. Insect declines have been widely documented and causes of these declines are attributed to human impacts including climate change, habitat loss and degradation, agricultural intensification including pesticides, and introduction of non-native species. However, we do not yet understand the relative importance and synergies of each of these factors. Although we have detailed records of recent changes in insect diversity and abundance in some regions of the globe, longer-term records (50 years) are rare. These long-term records are important for understanding when large scale insect declines began, how far it has progressed, and whether recent variations in insect populations are within the range of normal changes. Our understanding of this biodiversity crisis is also limited because previous work has mainly focused on certain groups of insects, like pollinators and butterflies, and we have little or no knowledge of whether or how other groups have been impacted. This research will analyze insect DNA from lake sediment cores in California to reconstruct a 1,200-year record of insect diversity change. By using DNA analysis, the researchers will be able to study insect species which have not previously received much research attention. The project will also assemble data on land use change, climate change, and pesticide applications, to link these human impacts with insect diversity through time. This research advances biodiversity conservation by improving our baseline understanding of insect declines, and distinguishing natural changes in insect diversity from those caused by human impacts over the last century. This project will contribute to the development of new research techniques and biodiversity monitoring technology. This project will utilize sediment cores collected from a marsh and hydrologically connected reservoir at Jasper Ridge Biological Preserve (JRBP) in the San Francisco Bay Area (California, USA). Together these cores span a period of increasing local and global human impacts. The researchers will employ both traditional palaeoecological tools as well as emerging sedimentary DNA (sedaDNA) techniques. To characterize insect diversity through time, the researchers will analyze sedaDNA from the sediment cores using metabarcoding and high-throughput sequencing. To develop high-resolution records of insect diversity change, the researchers will use geochemical and microfossil analyses, sedaDNA, and historical records. This multi-proxy, high-resolution data set will then be statistically queried using several multivariate modeling approaches.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.