Conserving biodiversity in the face of ever-increasing human pressure is hampered by our lack of basic information on species occurrence, distribution, abundance, habitat requirements, and threats. Obtaining this information requires efficient and sensitive methods capable of detecting and quantifying true occurrence and diversity, including rare, cryptic and elusive species. Environmental DNA (eDNA) is an emerging technique that can increase our ability to detect and quantify biodiversity, by overcoming some of the challenges of labor-intensive traditional surveys. The application of eDNA in ecology and conservation has grown enormously in recent years, but without a concurrent growth in appreciation of its strengths and limitations. In many situations, eDNA may either not work, or it may work but not provide the information needed. Problems with (1) imperfect detection, (2) abundance quantification, (3) taxonomic assignment, (4) eDNA spatial and temporal dynamics, (5) data analysis and interpretation, and (6) assessing ecological status have all been significant. The technique has often been used without a careful evaluation of the technical challenges and complexities involved, and a determination made that eDNA is the appropriate method for the species or environment of interest. It is therefore important to evaluate the scope and relevance of eDNA-based studies, and to identify critical considerations that need to be taken into account before using the approach. We review and synthesize eDNA studies published to date to highlight the opportunities and limitations of utilizing eDNA in ecology and conservation. We identify potential ways of reducing limitations in eDNA analysis, and demonstrate how eDNA and traditional surveys can complement each other.

由于我们缺乏有关物种发生，分布，丰富度，栖息地要求和威胁的基本信息，因此在人类压力不断增加的情况下保护生物多样性受到了阻碍。获取此信息需要有效且敏感的方法，这些方法应能够检测和量化真实的事件和多样性，包括稀有，隐秘和难以捉摸的物种。通过克服劳动密集型传统调查的某些挑战，环境DNA（eDNA）是一种新兴技术，可以提高我们检测和量化生物多样性的能力。近年来，eDNA在生态和保护中的应用取得了巨大的增长，但是在认识到其优势和局限性的同时却没有同时增长。在许多情况下，eDNA可能无法运行，或者可能无法运行，但无法提供所需的信息。（1）检测不完善，（2）丰度定量，（3）分类分配，（4）eDNA时空动态，（5）数据分析和解释以及（6）评估生态状况等问题都非常重要。该技术经常在没有仔细评估所涉及的技术挑战和复杂性的情况下使用，并且确定eDNA是关注的物种或环境的合适方法。因此，重要的是评估基于eDNA的研究的范围和相关性，并确定在使用该方法之前需要考虑的关键因素。我们回顾并综合了迄今为止发表的eDNA研究，以突出利用eDNA进行生态和保护的机会和局限性。