The trouble with MEAM2: Implications of pseudogenes on species delimitation in the globally invasive Bemisia tabaci (Hemiptera: Aleyrodidae) cryptic species complex

Tay W.T, Elfekih S.,Court L.N., Gordon K.H.J, Delatte H., De Barro P.J.2017. The trouble with MEAM2: Implications of pseudogenes on species delimitation in the globally invasive Bemisia tabaci (Hemiptera: Aleyrodidae) cryptic species complex, Genome Biology and Evolution, , evx173, https://doi.org/10.1093/gbe/evx173

Abstract

Molecular species identification using sub-optimal PCR primers can over-estimate species diversity due to co-amplification of nuclear mitochondrial (NUMT) DNA/pseudogenes. For the agriculturally important whitefly Bemisia tabaci cryptic pest species complex, species identification depends primarily on characterisation of the mitochondrial DNA cytochrome oxidase I (mtDNA COI) gene. The lack of robust PCR primers for the mtDNA COI gene can undermine correct species identification which in turn compromises management strategies. This problem is identified in the B. tabaciAfrica/Middle East/Asia Minor clade which comprises the globally invasive Mediterranean (MED) and Middle East Asia Minor I (MEAM1) species, Middle East Asia Minor 2 (MEAM2), and the Indian Ocean (IO) species. Initially identified from the Indian Ocean island of Réunion, MEAM2 has since been reported from Japan, Peru, Turkey and Iraq. We identified MEAM2 individuals from a Peruvian population via Sanger sequencing of the mtDNA COI gene. In attempting to characterise the MEAM2 mitogenome, we instead characterised mitogenomes of MEAM1. We also report on the mitogenomes of MED, AUS and IO thereby increasing genomic resources for members of this complex. Gene synteny (i.e., same gene composition and orientation) was observed with published B. tabaci cryptic species mitogenomes. Pseudogene fragments matching MEAM2 partial mtDNA COI gene exhibited low frequency single nucleotide polymorphisms that matched low copy number DNA fragments (<3%) of MEAM1 genomes, while presence of internal stop codons, loss of expected stop codons and poor primer annealing sites, all suggested MEAM2 as a pseudogene artefact and so not a real species.

Publiée : 18/09/2017

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