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

昆虫占地球上所描述物种的一半以上，在生态过程、生态系统功能和人类福祉中发挥着关键作用。昆虫数量的减少已被广泛记录在案，造成这些减少的原因是人类的影响，包括气候变化、栖息地丧失和退化、农业集约化（包括杀虫剂）以及引进非本地物种。然而，我们还不了解这些因素中每一个的相对重要性和协同作用。虽然我们有详细的记录，最近的变化，昆虫的多样性和丰富性在地球仪的一些地区，长期的记录（50年）是罕见的。这些长期记录对于了解大规模昆虫衰退何时开始，进展到何种程度以及昆虫种群的近期变化是否在正常变化范围内非常重要。我们对这场生物多样性危机的理解也是有限的，因为以前的工作主要集中在某些昆虫群体上，如传粉者和蝴蝶，我们对其他群体是否或如何受到影响知之甚少。这项研究将分析来自加州湖泊沉积物岩心的昆虫DNA，以重建1,200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利用变化、气候变化和农药应用的数据，将这些人类影响与昆虫多样性联系起来。这项研究通过提高我们对昆虫减少的基本认识，并将昆虫多样性的自然变化与上个世纪人类影响造成的变化区分开来，从而促进了生物多样性保护。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。该项目将利用从弗朗西斯科湾区（美国加州）碧玉岭生物保护区（JRBP）的沼泽和水文连接水库收集的沉积物岩心。这些核心共同跨越了一个不断增加的地方和全球人类影响的时期。研究人员将采用传统的古生态工具以及新兴的沉积DNA（sedaDNA）技术。为了表征昆虫在不同时间的多样性，研究人员将使用元条形码和高通量测序分析沉积物芯中的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。该奖项反映了NSF的法定使命，并已被认为是值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

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.