Cognato Anthony I
Department of Entomology, Michigan State University, East Lansing, MI 48824, USA.
J Econ Entomol. 2006 Aug;99(4):1037-45. doi: 10.1603/0022-0493-99.4.1037.
Diagnosis and assessment of species boundaries of economically important insects are often problematic because of limited morphological and/or biological characters. DNA data can help to identify and revise species. Nonoverlapping intra- and interspecific sequence divergences are often used as evidence for species. Thus, the establishment of a standardized percent nucleotide divergence to predict species boundaries would aid in cases where species status is suspect. However, given variation in nucleotide mutation rates and species concepts, association between a standard percent sequence divergence and species is questionable. This review surveys the percent DNA sequence difference found between sister-species of economically important insects, to assess whether a standard divergence associates with all taxa. Sixty-two comparisons of intra- and interspecific pairwise DNA differences were made for mitochondrial and nuclear loci spanning families of Isoptera, Phthiraptera, Hemiptera, Coleoptera, Lepidoptera, Diptera, and Hymenoptera. Intra- and interspecific sequence divergences varied widely among insects, 0.04-26.0 and 1.0-30.7%, respectively. The ranges of intra- and interspecific sequence divergences overlapped in 28 of 62 comparisons. This implies that a standardized percent sequence divergence would fail to correctly diagnose species for 45% of the cases. Common occurrence of nonmonophyly among closely related species probably explains this observation. Nonmonophyly and overlap of intra- and interspecific divergences were significantly associated. The reviewed studies suggest that a standard percent sequence divergence does not predict species boundaries among economically important insects. DNA data can help best to predict species boundaries via its inclusion in nonphenetic phylogenetic analysis and subsequent systematic expert scrutiny.
由于形态学和/或生物学特征有限，对经济上重要昆虫的物种界限进行诊断和评估往往存在问题。DNA数据有助于识别和修订物种。种内和种间序列分歧不重叠通常被用作物种的证据。因此，建立一个标准化的核苷酸分歧百分比来预测物种界限将有助于处理物种地位存疑的情况。然而，考虑到核苷酸突变率和物种概念的差异，标准序列分歧百分比与物种之间的关联是值得怀疑的。本综述调查了经济上重要昆虫的姊妹种之间的DNA序列差异百分比，以评估标准分歧是否与所有分类群相关。对等翅目、啮目、半翅目、鞘翅目、鳞翅目、双翅目和膜翅目各科的线粒体和核基因座进行了62次种内和种间成对DNA差异比较。昆虫的种内和种间序列分歧差异很大，分别为0.04 - 26.0%和1.0 - 30.7%。在62次比较中，有28次种内和种间序列分歧范围重叠。这意味着标准化的序列分歧百分比在45%的情况下无法正确诊断物种。密切相关物种中常见的非单系性可能解释了这一现象。非单系性与种内和种间分歧的重叠显著相关。综述研究表明，标准序列分歧百分比无法预测经济上重要昆虫的物种界限。DNA数据通过纳入非表型系统发育分析和随后的系统专家审查，最有助于预测物种界限。
