Abstract
Megaloptera are a basal holometabolous insect order with larvae exclusively predacious and aquatic. The evolutionary history of Megaloptera attracts great interest because of its antiquity and important systematic status in Holometabola. However, due to the difficulties identifying morphological apomorphies for the group, controversial hypotheses on the monophyly and higher phylogeny of Megaloptera have been proposed. Herein, we describe the complete mitochondrial (mt) genome of a fishfly species, Neochauliodes punctatolosus Liu & Yang, 2006, representing the first mt genome of the subfamily Chauliodinae. A phylogenomic analysis was carried out based on the mt genomic sequences of 13 mt protein-coding genes (PCGs) and two rRNA genes of nine Neuropterida species, comprising all three orders of Neuropterida and all families and subfamilies of Megaloptera. Both maximum likelihood and Bayesian inference analyses highly support the monophyly of Megaloptera, which was recovered as the sister of Neuroptera. Within Megaloptera, the sister relationship between Corydalinae and Chauliodinae was corroborated. The divergence time estimation suggests that stem lineage of Neuropterida and Coleoptera separated in the Early Permian. The interordinal divergence within Neuropterida might have occurred in the Late Permian.
Highlights
Mitochondria are important functional organelles in eukaryotic cells [1], and the mitochondrial genome is being widely used for studies on evolutionary biology, because the mt genome sequences can be more phylogenetically informative than shorter sequences of individual genes, and provide multiple genome-level characteristics, such as the relative position of different genes, RNA secondary structures, and modes of control of replication and transcription [2,3,4,5]
In many mt genomic papers, while a well resolved topology is recovered, it frequently contradicts all previous estimates of phylogeny based on single sequences, nuclear genes, and even morphology [6,7,8], which might be caused by overly complicated evolutionary models among the mitochondrial genes, errors in methodology processing the genomic data, and biases in taxon sampling [9,10]
Within Neuropterida mt genomes, the length variation is minimal in proteincoding genes (PCGs), tRNAs, rrnL and rrnS, but very different in the putative control region (Figure 2; Table S2)
Summary
Mitochondria are important functional organelles in eukaryotic cells [1], and the mitochondrial genome is being widely used for studies on evolutionary biology, because the mt genome sequences can be more phylogenetically informative than shorter sequences of individual genes, and provide multiple genome-level characteristics, such as the relative position of different genes, RNA secondary structures, and modes of control of replication and transcription [2,3,4,5]. As of 26 May 2012, 2627 complete Metazoa mt genomes have been sequenced and deposited in GenBank (http://www.ncbi.nlm.nih.gov), including 278 complete insect mt genomes from representative taxa of 26 orders. Megaloptera are one of the orders of the superorder Neuropterida (lacewings and allies) and are generally considered to be among the most archaic holometabolous insects because of their origin indicated by the earliest fossil evidence found in Late. Adult Corydalidae are impressive and often look aggressive due to the large body (body length frequently greater than 90 mm) and wings, sometimes with distinctive colour patterns, and the tapered mandibles (Figure 1). The larvae of Megaloptera are exclusively aquatic, predatory, and frequently dominate the predatory guild in lotic habitats such as streams, shallow rivers, ponds, etc [12]
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