Selected Lark Mitochondrial Genomes Provide Insights into the Evolution of Second Control Region with Tandem Repeats in Alaudidae (Aves, Passeriformes).

Abstract

The control region (CR) regulates the replication and transcription of the mitochondrial genome (mitogenome). Some avian mitogenomes possess two CRs, and the second control region (CR2) may enhance replication and transcription; however, the CR2 in lark mitogenome appears to be undergoing loss and is accompanied by tandem repeats. Here, we characterized six lark mitogenomes from Alaudala cheleensis, Eremophila alpestris, Alauda razae, and Calandrella cinerea and reconstructed the phylogeny of Passerida. Through further comparative analysis among larks, we traced the evolutionary process of CR2. The mitochondrial gene orders were conserved in all published lark mitogenomes, with Cytb-trnT-CR1-trnP-ND6-trnE-remnant CR2 with tandem repeat-trnF-rrnS. Phylogenetic analysis revealed Alaudidae and Panuridae are sister groups at the base of Sylvioidea, and sporadic losses of CR2 may occur in their common ancestor. CR sequence and phylogeny analysis indicated CR2 tandem repeats were generated within CR2, originating in the ancestor of all larks, rather than inherited from CR1. The secondary structure comparison of tandem repeat units within and between species suggested slipped-strand mispairing and DNA turnover as suitable models for explaining the origin and evolution of these repeats. This study reveals the evolutionary process of the CR2 containing tandem repeat in Alaudidae, providing reference for understanding the evolutionary characteristics and dynamics of tandem repeats.