Cervantes Fernando A, Arcangeli Jésica, Hortelano-Moncada Yolanda, Borisenko Alex V
Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, C.P. 04510 México, Distrito Federal, Mexico.
Mitochondrial DNA. 2010 Dec;21 Suppl 1:44-50. doi: 10.3109/19401736.2010.538051.
Two morphologically similar species of opossum from the genus Didelphis-Didelphis virginiana and Didelphis marsupialis-cooccur sympatrically in Mexico. High intraspecific variation complicates their morphological discrimination, under both field and museum conditions. This study aims to evaluate the utility and reliability of using DNA barcodes (short standardized genome fragments used for DNA-based identification) to distinguish these two species. Sequences of the cytochrome c oxidase subunit I (Cox1) mitochondrial gene were obtained from 12 D. marsupialis and 29 D. virginiana individuals and were compared using the neighbor-joining (NJ) algorithm with Kimura's two-parameter (K2P) model of nucleotide substitution. Average K2P distances were 1.56% within D. virginiana and 1.65% in D. marsupialis. Interspecific distances between D. virginiana and D. marsupialis varied from 7.8 to 9.3% and their barcode sequences formed distinct non-overlapping clusters on NJ trees. All sympatric specimens of both species were effectively discriminated, confirming the utility of Cox1 barcoding as a tool for taxonomic identification of these morphologically similar taxa.
负鼠属（Didelphis）的两种形态相似的负鼠——弗吉尼亚负鼠（Didelphis virginiana）和北美负鼠（Didelphis marsupialis）——在墨西哥同域共存。种内高度变异使得在野外和博物馆条件下对它们进行形态学鉴别变得复杂。本研究旨在评估使用DNA条形码（用于基于DNA的鉴定的短标准化基因组片段）区分这两个物种的实用性和可靠性。从12只北美负鼠个体和29只弗吉尼亚负鼠个体中获得了细胞色素c氧化酶亚基I（Cox1）线粒体基因的序列，并使用邻接法（NJ）算法和木村双参数（K2P）核苷酸替代模型进行比较。弗吉尼亚负鼠种内的平均K2P距离为1.56%，北美负鼠种内为1.65%。弗吉尼亚负鼠和北美负鼠之间的种间距离在7.8%至9.3%之间，它们的条形码序列在NJ树上形成了不同的非重叠簇。两个物种的所有同域标本都得到了有效鉴别，证实了Cox1条形码作为一种工具用于对这些形态相似的分类群进行分类鉴定的实用性。
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