Could pseudogenes be widespread in ants? Evidence of numts in the leafcutter ant Acromyrmex striatus (Roger, 1863) (Formicidae: Attini)

Abstract

The incorporation of fragments of mitochondrial DNA (mtDNA) in the nuclear genome, known as numts (nuclear mitochondrial pseudogenes), undermines general assumptions concerning the use of mtDNA in phylogenetic and phylogeographic studies. Accidental amplifications of these nuclear copies instead of the mitochondrial target can lead to crucial misinterpretations, thus the correct identification of numts and their differentiation from true mitochondrial sequences are important in preventing this kind of error. Our goal was to describe the existence of cytochrome b (cytb) numts in the leafcutter ant Acromyrmex striatus (Roger, 1863). PCR products were directly sequenced using a pair of universal primers designed to amplify the cytb gene of these insects. Other species of leafcutter ants were also sequenced. The sequences were analyzed and the numts were identified by the presence of double peaks, indels and premature stop codons. Only A. striatus clearly showed the presence of numts, while the other species displayed the expected amplification of the mtDNA cytb gene target using the same primer pair. We hope that our report will highlight the benefits and challenges of using mtDNA in the molecular phylogenetic reconstruction and phylogeographic studies of ants, while establishing the importance of numts reports for future studies.