Biology subjects

ffrench-Constant, R.

Publications and source records attributed to ffrench-Constant, R..

4 recordsLinked to original sources

bioRxiv2023

Lepidopteran Synteny Units (LSUs) reveal deep conservation of macrosynteny in butterflies and moths

Advances in DNA sequencing technologies have, for the first time, provided us with enough whole chromosome-level genomes to understand in detail how chromosome number and composition change over time. Here, we use the genomes of butterflies and moths to look at the levels and age of macrosynteny in the Lepidoptera and Trichoptera. We used comparative BUSCO analsysis to define reproducible units of macrosynteny which we term Lepidopteran Synteny Units or LSUs. The 31 chromosomes of the model butterfly Melitaea cinxia served as a reference point. The results show that chromosome-wide macrosynteny extends from the most basal branches of the Lepidopteran phylogeny to the most distal. This synteny also extends to the order Trichoptera, a sister group of the Lepidoptera. Thus, chromosome-wide macrosynteny has been conserved for a period of >200 My in this group of insects. We found no major interchromosomal translocations, reciprocal or non-reciprocal, in the genomes studied. Intrachromosomal rearrangements, in contrast, were abundant. Beyond its use in defining LSUs, this type of homology-based analysis will be useful in determining the relationships between chromosomal elements in different animals and plants. Further, by more precisely defining the breakpoints of chromosomal rearrangements we can begin to look at their potential roles in chromosomal evolution. StatementThe authors declare no conflicting interests ContributionsConceptualisation: W.T., R.H.f.; data analysis: W.T.; writing & editing: W.T., K.S., R.H.f All authors read and approved the final manuscript.

genomics↗

bioRxiv2021

Stepwise evolution of a butterfly supergene via duplication and inversion

Supergenes maintain adaptive clusters of alleles in the face of genetic mixing. Although usually attributed to inversions, supergenes can be complex, and reconstructing the precise processes that led to recombination suppression and their timing is challenging. We investigated the origin of the BC supergene, which controls variation in warning colouration in the African Monarch butterfly, Danaus chrysippus. By generating chromosome-scale assemblies for all three alleles, we identified multiple structural differences. Most strikingly, we find that a region of >1 million bp underwent several segmental duplications at least 7.5 million years ago. The resulting duplicated fragments appear to have triggered four inversions in surrounding parts of the chromosome, resulting in stepwise growth of the region of suppressed recombination. Phylogenies for the inversions are incongruent with the species tree, and suggest that structural polymorphisms have persisted for at least 4.1 million years. In addition to the role of duplications in triggering inversions, our results suggest a previously undescribed mechanism of recombination suppression through independent losses of divergent duplicated tracts. Overall, our findings add support for a stepwise model of supergene evolution involving a variety of structural changes.

evolutionary biology↗

bioRxiv2021

Genome assembly of Danaus chrysippus and comparison with the Monarch Danaus plexippus

Milkweed butterflies in the genus Danaus are studied in a diverse range of research fields including the neurobiology of migration, biochemistry of plant detoxification, host-parasite interactions, evolution of sex chromosomes, and speciation. We have assembled a nearly chromosomal genome for Danaus chrysippus (known as the African Monarch, African Queen, and Plain Tiger) using long read sequencing data. This species is of particular interest for the study of genome structural change and its consequences for evolution. Comparison with the genome of the North American Monarch Danaus plexippus reveals generally strong synteny, but highlights three inversion differences. The three chromosomes involved were previously found to carry peaks of intra-specific differentiation in D. chrysippus in Africa, suggesting that these inversions may be polymorphic and associated with local adaptation. The D. chrysippus genome is over 40% larger than that of D. plexippus, and nearly all of the additional [~]100 Megabases of DNA comprises repeats. Future comparative genomic studies within this genus will shed light on the evolution of genome architecture.

genomics↗

bioRxiv2019

De novo genome assembly of the meadow brown butterfly, Maniola jurtina

BackgroundMeadow brown butterflies (Maniola jurtina) on the Isles of Scilly represent an ideal model in which to dissect the links between genotype, phenotype and long-term patterns of selection in the wild - a largely unfulfilled but fundamental aim of modern biology. To meet this aim, a clear description of genotype is required.\n\nFindingsHere we present the draft genome sequence of M. jurtina to serve as an initial genetic resource for this species. Seven libraries were constructed using DNA from multiple wild caught females and sequenced using Illumina, PacBio RSII and MinION technology. A novel hybrid assembly approach was employed to generate a final assembly with an N50 of 214 kb (longest scaffold 2.9 Mb). The genome encodes a total of 36,294 genes. 90.3% and 88.7% of core BUSCO (Benchmarking Universal Single-Copy Orthologs) Arthropoda and Insecta gene sets were recovered as complete single-copies from this assembly. Comparisons with 17 other Lepidopteran species placed 86.5% of the assembled genes in orthogroups.\n\nConclusionsOur results provide the first high-quality draft genome and annotation of the butterfly M. jurtina.

genomics↗