Abstract: DNA barcode is a special DNA sequence which can be used as a tool for species identification. At present, the most commonly used DNA barcode in zoological study is a sequence coming from cytochrome c oxidase subunit 1 (COI). With the establishment of standard data bases, the COIbased DNA barcode has gained its wide application in animal taxonomy and ecology, and profoundly affected these research fields. However, the silent assumptions for DNA barcode that related to the evolution history and inheritance of mitochondria and speciation haven’t been completely confirmed, and thus, some problems are created. This paper discussed the effects of COIbased DNA barcode on animal taxonomy and ecology, the existing problems in its studies, and the future prospect of its applications.

Key words: Mixed rare earth elements, Yellow cinnamon soil, Soil microbes, Low dosage accumulation, EC₅₀