High-quality haploid genomes corroborate 29 chromosomes and highly conserved synteny of genes inHyleshawkmoths (Lepidoptera: Sphingidae)

Abstract

AbstractBackgroundSimilarity of wing patterns does not correlate with phylogenetic relationships in the young genusHyles. Speciation is an ongoing process, as is hybridization because reproductive barriers are still low. Genomic data promise insights into various aspects of speciation in the spurge hawkmoth (Hyles euphorbiae), we thus assembled a chromosome-level genome and investigated some characteristics.ResultsTheH. euphorbiaemale genome was sequenced using PacBio and amended by Hi-C Illumina data, yielding a 504 Mb assembly (scaffold N50 of 18.2 Mb) with 99.9% of the data represented by the 29 largest scaffolds forming the haploid chromosome set. Consistent with this, FISH analysis of the karyotype revealedn= 29 chromosomes and a WZ/ZZ (female/male) sex chromosome system inH. euphorbiae. Estimates of chromosome length based on the karyotype image provided an additional quality metric of assembled chromosome size and confirmed the WZ sex chromosomes as the largest chromosome pair in the karyotype. Additional Hi-C data were used to scaffold the publishedH. vespertiliomale genome into chromosomes, resulting in a high-quality assembly (651 Mb) with a scaffold N50 of 22 Mb and 98% of sequence data placed in the 29 largest scaffolds (chromosomes). The measured genome sizes ofH. euphorbiaeandH. vespertiliohad an average 1C DNA value of 472 Mb and 562 Mb, respectively. The larger genome size ofH. vespertiliowas accompanied by a proportional increase in repeats from 45% inH. euphorbiaeto almost 55% inH. vespertilio. In bothHylesspecies, the three wing pattern genes,optix, WntA, andcortex, were found on chromosomes 23, 28, and 17, respectively, with varying amounts and positions of indels possibly corrupting their function.ConclusionsThe comparison of high-quality annotated chromosome-level assemblies inH. euphorbiaeandH. vespertiliorevealed highly conserved synteny of genes between these two species, but significant differences in repetitive DNA content. The identification of wing pattern genes promises future understanding of the evolution of forewing patterns in the genusHyles, although further sequencing data from more individuals are needed. The genomic data obtained provide additional reliable references for further comparative studies in hawkmoths (Sphingidae).