No evidence for maintenance of a sympatric<i>Heliconius</i>species barrier by chromosomal inversions

Understanding the production, response, and genetics of signals used in mate choice can inform our understanding of the evolution of both intraspecific mate choice and reproductive isolation. Sex pheromones are important for courtship and mate choice in many insects, but we know relatively little of their role in butterflies. The butterfly Heliconius melpomene uses a complex blend of wing androconial compounds during courtship. Electroantennography in H. melpomene and its close relative Heliconius cydno showed that responses to androconial extracts were not species specific. Females of both species responded equally strongly to extracts of both species, suggesting conservation of peripheral nervous system elements across the two species. Individual blend components provoked little to no response, with the exception of octadecanal, a major component of the H. melpomene blend. Supplementing octadecanal on the wings of octadecanal‐rich H. melpomene males led to an increase in the time until mating, demonstrating the bioactivity of octadecanal in Heliconius. Using quantitative trait locus (QTL) mapping, we identified a single locus on chromosome 20 responsible for 41% of the parental species’ difference in octadecanal production. This QTL does not overlap with any of the major wing color or mate choice loci, nor does it overlap with known regions of elevated or reduced FST. A set of 16 candidate fatty acid biosynthesis genes lies underneath the QTL. Pheromones in Heliconius carry information relevant for mate choice and are under simple genetic control, suggesting they could be important during speciation.

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“…Perhaps the selection‐favoring genetic linkage is weak in these species now that speciation is nearly complete (see also Davey et al. ).…”

Section: Discussionmentioning

confidence: 99%

“…Individuals were genotyped either by RAD sequencing as previously described (Davey et al. ; Merrill et al. ) or low‐coverage whole genome sequencing using nextera‐based libraries.…”

Section: Methodsmentioning

confidence: 99%

A major locus controls a biologically active pheromone component inHeliconius melpomene

et al. 2020

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“…Recently, an updated assembly of the H. melpomene genome was released, with improved scaffolding. Additionally, two independent assemblies of the congener Heliconius erato were published, including one with extensive linkage mapping to assign scaffolds to chromosomes (Davey et al, 2017;Joron et al, 2011;Lewis et al, 2016;Martin et al, 2016;Van Belleghem et al, 2017). Extensive population genomic analyses have been performed in Heliconius butterflies (Harpel et al, 2015;Nadeau et al, 2014), yielding notable insights into patterns of speciation and introgression as well as the genetic basis of wing coloration.…”

Section: Butterflies As Models In Ecological and Evolutionary Genomicsmentioning

confidence: 99%

Insect genomes: progress and challenges

Zhao

et al. 2019

Insect Molecular Biology

136

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In the wake of constant improvements in sequencing technologies, numerous insect genomes have been sequenced. Currently, 1219 insect genome‐sequencing projects have been registered with the National Center for Biotechnology Information, including 401 that have genome assemblies and 155 with an official gene set of annotated protein‐coding genes. Comparative genomics analysis showed that the expansion or contraction of gene families was associated with well‐studied physiological traits such as immune system, metabolic detoxification, parasitism and polyphagy in insects. Here, we summarize the progress of insect genome sequencing, with an emphasis on how this impacts research on pest control. We begin with a brief introduction to the basic concepts of genome assembly, annotation and metrics for evaluating the quality of draft assemblies. We then provide an overview of genome information for numerous insect species, highlighting examples from prominent model organisms, agricultural pests and disease vectors. We also introduce the major insect genome databases. The increasing availability of insect genomic resources is beneficial for developing alternative pest control methods. However, many opportunities remain for developing data‐mining tools that make maximal use of the available insect genome resources. Although rapid progress has been achieved, many challenges remain in the field of insect genomics.

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“…We assembled a high quality draft genome for D. chrysippus, with a total length of 322 Megabases (Mb), a scaffold N50 length of 0.63 Mb, and a BUSCO [28] completeness score of 94% (S1 Table-S8 Table). We then further scaffolded the genome into a pseudo-chromosomal assembly based on homology with the Heliconius melpomene genome [29][30][31] accounting for known fusions that differentiate these species [9,30,32] (Fig. S1).…”

Section: Identification Of the Bc Supergenementioning

confidence: 99%

Whole-chromosome hitchhiking driven by a male-killing endosymbiont

Martin

Singh

Gordon³

et al. 2019

Preprint

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Neo-sex chromosomes are found in many taxa, but the forces driving their emergence and spread are poorly understood. The female-specific neo-W chromosome of the African monarch (or queen) butterfly Danaus chrysippus presents an intriguing case study because it is restricted to a single 'contact zone' population, involves a putative colour patterning supergene, and cooccurs with infection by the the male-killing endosymbiont Spiroplasma. We investigated the origin and evolution of this system using whole genome sequencing. We first identify the 'BC supergene', a broad region of suppressed recombination across nearly half a chromosome, which links two colour patterning loci. Association analysis suggests that the genes yellow and arrow in this region control the forewing colour pattern differences between D. chrysippus subspecies. We then show that the same chromosome has recently formed a neo-W that has spread through the contact zone within ~2200 years. We also assembled the genome of the male-killing Spiroplasma, and find that it shows perfect genealogical congruence with the neo-W, suggesting that the neo-W has hitchhiked to high frequency as the male killer has spread through the population. The complete absence of female crossing-over in the Lepidoptera causes wholechromosome hitchhiking of a single neo-W haplotype, carrying a single allele of the BC supergene, and dragging multiple non-synonymous mutations to high frequency. This has created a population of infected females that all carry the same recessive colour patterning allele, making the phenotypes of each successive generation highly dependent on uninfected male immigrants. Our findings show how hitchhiking can occur between the unlinked genomes of host and endosymbiont, with dramatic consequences. . Smith DAS, Owen DF, Gordon IJ, Lowis NK. The butterfly Danaus chrysippus ( L .) in East Afiica : polymorphism and morph-ratio clines within a complex , extensive and dynamic hybrid zone. Zool J Linn Soc. 1997;120: 51-78. 17. Smith DAS. Heterosis, epistasis and linkage disequilibrium in a wild population of the polymorphic butterfly Danaus chrysippus ( L .). Zool J Linn Soc. 1980;69: 87-109. 18. Smith D a S, Owen DF, Gordon IJ, Owiny AM. Polymorphism and evolution in the butterfly Danaus chrysippus (L.) (Lepidoptera: Danainae).

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No evidence for maintenance of a sympatricHeliconiusspecies barrier by chromosomal inversions

Cited by 95 publications

References 98 publications

A major locus controls a biologically active pheromone component inHeliconius melpomene

A major locus controls a biologically active pheromone component inHeliconius melpomene

Insect genomes: progress and challenges

Whole-chromosome hitchhiking driven by a male-killing endosymbiont

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