Molecular tools are an indispensable part of ecology and biodiversity sciences and implemented across all biomes. About a decade ago, the use and implementation of environmental DNA (eDNA) to detect biodiversity signals extracted from environmental samples opened new avenues of research. Initial eDNA research focused on understanding population dynamics of target species. Its scope thereafter broadened, uncovering previously unrecorded biodiversity via metabarcoding in both well-studied and understudied ecosystems across all taxonomic groups. The application of eDNA rapidly became an established part of biodiversity research, and a research field by its own. Here, we revisit key expectations made in a land-mark special issue on eDNA in Molecular Ecology in 2012 to frame the development in six key areas: (1) sample collection, (2) primer development, (3) biomonitoring, (4) quantification, (5) behaviour of DNA in the environment and (6) reference database development. We pinpoint the success of eDNA, yet also discuss shortfalls and expectations not met, highlighting areas of research priority and identify the unexpected developments. In parallel, our retrospective couples a screening of the peer-reviewed literature with a survey of eDNA users including academics, end-users and commercial providers, in which we address the priority areas to focus research efforts to advance the field of eDNA. With the rapid and ever-increasing pace of new technical advances, the future of eDNA looks bright, yet successful applications and best practices must become more interdisciplinary to reach its full potential. Our retrospect gives the tools and expectations towards concretely moving the field forward.

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环境 DNA：下一章

分子工具是生态学和生物多样性科学不可或缺的一部分，并在所有生物群落中得到应用。大约十年前，使用和实施环境 DNA (eDNA) 来检测从环境样本中提取的生物多样性信号，开辟了新的研究途径。最初的 eDNA 研究侧重于了解目标物种的种群动态。此后，其范围扩大了，通过元条形码在所有分类群中经过充分研究和研究不足的生态系统中发现了以前未记录的生物多样性。 eDNA 的应用迅速成为生物多样性研究的既定组成部分，并成为一个独立的研究领域。在这里，我们重新审视 2012 年分子生态学中 eDNA 的里程碑式特刊中提出的主要期望，以框架六个关键领域的发展：(1) 样本收集，(2) 引物开发，(3) 生物监测，(4)定量，(5) DNA 在环境中的行为以及 (6) 参考数据库开发。我们指出了 eDNA 的成功，同时也讨论了不足和未满足的期望，强调了研究重点领域并确定了意外的发展。与此同时，我们的回顾会将同行评审文献的筛选与对 eDNA 用户（包括学术界、最终用户和商业提供商）的调查结合起来，其中我们讨论了重点领域，以集中研究工作来推进 eDNA 领域的发展。随着新技术进步的快速且不断加快，eDNA 的未来看起来很光明，但成功的应用和最佳实践必须变得更加跨学科，才能充分发挥其潜力。我们的回顾提供了具体推动该领域前进的工具和期望。