Morphology versus DNA barcoding: two sides of the same coin. A case study of Ceutorhynchus erysimi and C. contractus identification.

Svetlana Stepanović,Jelena Jović,Andrea Kosovac,Ivo Toševski,Oliver Krstić

doi:10.1111/1744-7917.12212

Svetlana Stepanović, Jelena Jović + Show 3 more

Open Access

https://doi.org/10.1111/1744-7917.12212

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Abstract

Genotyping of 2 well-known weevil species from the genus Ceutorhynchus (Coleoptera: Curculionidae) distributed in west Palearctic, C. erysimi and C. contractus, revealed phenotype versus genotype inconsistencies in a set of 56 specimens (25 C. erysimi and 31 C. contractus) collected from 25 locations in Serbia and Montenegro. An analysis of the mitochondrial cytochrome oxidase subunit I gene (COI), widely used as a barcoding region, and a nuclear gene, elongation factor-1α (EF-1α), revealed stable genetic divergence among these species. The average uncorrected pairwise distances for the COI and EF-1α genes were 3.8%, and 1.3%, respectively, indicating 2 genetically well-segregated species. However, the genetic data were not congruent with the phenotypic characteristics of the studied specimens. In the first place, C. erysimi genotypes were attached to specimens with phenotypic characteristics of C. contractus. Species-specific PCR-RFLP assays for the barcoding gene COI were applied for the molecular identification of 101 additional specimens of both morphospecies (33 C. erysimi and 68 C. contractus) and were found to confirm this incongruity. The discrepancy between the genetic and morphological data raises the question of the accuracy of using a barcoding approach, as it may result in misleading conclusions about the taxonomic position of the studied organism. Additionally, the typological species concept shows considerable weakness when genetic data are not supported with phenotypic characteristics as in case of asymmetric introgression, which may cause certain problems, especially in applied studies such as biological control programs in which the biological properties of the studied organisms are the main focus.

Highlights

We recorded 6 haplotypes for the with mitochondrial cytochrome oxidase subunit I gene (COI) gene of C. contractus of 31 analyzed specimens from 19 locations, whereas almost 3 times as many haplotypes were recorded for C. erysimi of 25 specimens collected from 12 locations
More haplotypes were identified in the elongation factor-1α (EF-1α) gene for C. contractus (= 13) than C. erysimi (= 8), the diversity of the EF-1α gene was expected to be lower for both species, given that nuclear EF-1α is a more conservative gene
The main finding of our study is the discrepancy between phenotypic and genotypic content in a subset of the analyzed specimens. This discrepancy was recorded primarily for specimens with phenotypic characteristics typical of C. contractus; mitochondrial genotypes typical for C. contractus were not recorded in specimens with the typical phenotype of C. erysimi (Fig. 2B)

Summary

Introduction

Insect Science published by Wiley Publishing Asia Pty Ltd on behalf of Institute of Zoology, Chinese Academy of Sciences Without doubt the barcoding initiative became an extraordinary useful tool for fast species identification and inventorying organisms (Miller, 2007), but the epistemological value of this method has been questioned by many authors (DeSalle et al, 2005; Brower, 2006; Meier et al, 2006; Song et al, 2008). The typological species concept is of essential importance for linking traditional taxonomy with novel approaches, such as DNA barcoding. Traditional taxonomy and DNA barcoding should not be treated as antagonistic methods, but rather as complementary approaches for resolving the phylogeny, taxonomy and nomenclature of living organisms (Packer et al, 2009; Taylor & Harris, 2012)

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