DNA barcodes effectively identify the morphologically similar Common Opossum (Didelphis marsupialis) and Virginia Opossum (Didelphis virginiana) from areas of sympatry in Mexico

Abstract

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.

Keywords::

• Cox1
• Didelphidae
• Didelphimorphia
• taxonomic identification
• genetic distance

Acknowledgements

The authors wish to thank the people, particularly Julieta Vargas who helped to collect field samples and curate specimens. Robert C. Dowler (ASUNHC), Loren K. Ammerman (ASUNHC), Silvia Hernández (FMVZ–UADY), and Consuelo Lorenzo (ECO-SC-M) graciously loaned opossum tissue samples. Comments and corrections by Jennifer Bain improved this manuscript. The Comisión Nacional para el Conocimiento y Uso de la Biodiversidad, Mexico partially financed this project through its program “Generación de Códigos de Barras del ADN de Especies Mexicanas”.

Declaration of interest: The authors report no conflict of interest. The authors alone are responsible for the content and writing of the paper.