Chromosome evolution presents an enigma in the mega-diverse Lepidoptera. Most species exhibit constrained chromosome evolution with nearly identical haploid chromosome counts and chromosome-level gene collinearity among species more than 140 million years divergent. However, a few species possess radically inflated chromosomal counts due to extensive fission and fusion events. To address this enigma of constraint in the face of an exceptional ability to change, we investigated an unprecedented reorganization of the standard lepidopteran chromosome structure in the green-veined white butterfly (Pieris napi). We find that gene content in P. napi has been extensively rearranged in large collinear blocks, which until now have been masked by a haploid chromosome number close to the lepidopteran average. We observe that ancient chromosome ends have been maintained and collinear blocks are enriched for functionally related genes suggesting both a mechanism and a possible role for selection in determining the boundaries of these genome-wide rearrangements.

Tradeoffs affect resource allocation during development and result in fitness consequences that drive the evolution of life history strategies. Yet despite their importance, we know little about the mechanisms underlying life history tradeoffs. Many species of Colias butterflies exhibit an alternative life history strategy (ALHS) where females divert resources from wing pigment synthesis to reproductive and somatic development. Due to this reallocation, a wing color polymorphism is associated with the ALHS: either yellow/orange or white. Here we map the locus associated with this ALHS in Colias crocea to a transposable element insertion located downstream of the Colias homolog of BarH-1, a homeobox transcription factor. Using CRISPR/Cas9 gene editing, antibody staining, and electron microscopy we find white-specific expression of BarH-1 suppresses the formation of pigment granules in wing scales and gives rise to white wing color. Lipid and transcriptome analyses reveal physiological differences associated with the ALHS. Together, these findings characterize a mechanism for a female-limited ALHS.

Herbal remedies are increasingly being recognised in recent years as alternative medicine for a number of diseases including cancer. Curcuma longa L., commonly known as turmeric is used as a culinary spice in India and in many Asian countries has been attributed to lower incidences of gastrointestinal cancers. Curcumin, a secondary metabolite isolated from the rhizomes of this plant has been shown to have significant anticancer properties, in addition to antimalarial and antioxidant effects. We sequenced the transcriptome of the rhizome of the 3 varieties of Curcuma longa L. using Illumina reversible dye terminator sequencing followed by de novo transcriptome assembly. Multiple databases were used to obtain a comprehensive annotation and the transcripts were functionally classified using GO, KOG and PlantCyc. Special emphasis was given for annotating the secondary metabolite pathways and terpenoid biosynthesis pathways. We report for the first time, the presence of transcripts related to biosynthetic pathways of several anti-cancer compounds like taxol, curcumin, and vinblastine in addition to anti-malarial compounds like artemisinin and acridone alkaloids, emphasizing turmeric's importance as a highly potent phytochemical. Our data not only provides molecular signatures for several terpenoids but also a comprehensive molecular resource for facilitating deeper insights into the transcriptome of C. longa.

BackgroundAlthough most insect species are specialized on one or few groups of plants, there are phytophagous insects that seem to use virtually any kind of plant as food. Understanding the nature of this ability to feed on a wide repertoire of plants is crucial for the control of pest species and for the elucidation of the macroevolutionary mechanisms of speciation and diversification of insect herbivores. Here we studied Vanessa cardui, the species with the widest diet breadth among butterflies and a potential insect pest, by comparing tissue-specific transcriptomes from caterpillars that were reared on different host plants. We tested whether the similarities of gene-expression response reflect the evolutionary history of adaptation to these plants in the Vanessa and related genera, against the null hypothesis of transcriptional profiles reflecting plant phylogenetic relatedness.ResultUsing both unsupervised and supervised methods of data analysis, we found that the tissue-specific patterns of caterpillar gene expression are better explained by the evolutionary history of adaptation of the insects to the plants than by plant phylogeny.ConclusionOur findings suggest that V. cardui may use two sets of expressed genes to achieve polyphagy, one associated with the ancestral capability to consume Rosids and Asterids, and another allowing the caterpillar to incorporate a wide range of novel host-plants.Electronic supplementary materialThe online version of this article (doi:10.1186/s12862-016-0627-y) contains supplementary material, which is available to authorized users.

While large-scale genomic approaches are increasingly revealing the genetic basis of polymorphic phenotypes such as colour morphs, such approaches are almost exclusively conducted in species with high-quality genomes and annotations. Here, we use Pool-Seq data for both genome assembly and SNP frequency estimation, followed by scanning for F outliers to identify divergent genomic regions. Using paired-end, short-read sequencing data from two groups of individuals expressing divergent phenotypes, we generate a de novo rough-draft genome, identify SNPs and calculate genomewide F differences between phenotypic groups. As genomes generated by Pool-Seq data are highly fragmented, we also present an approach for super-scaffolding contigs using existing protein-coding data sets. Using this approach, we reanalysed genomic data from two recent studies of birds and butterflies investigating colour pattern variation and replicated their core findings, demonstrating the accuracy and power of a Pool-Seq-only approach. Additionally, we discovered new regions of high divergence and new annotations that together suggest novel parallels between birds and butterflies in the origins of their colour pattern variation.

Taxonomic orders vary in their degree of chromosomal conservation with some having high rates of chromosome number turnover despite maintaining some core sets of ordered genes (e.g. Mammalia) and others exhibiting rapid rates of gene-order reshuffling without changing chromosomal count (e.g. Diptera). However few clades exhibit as much conservation as the Lepidoptera for which both chromosomal count and gene colinearity (synteny) are very high over the past 140 MY. In contrast, here we report extensive chromosomal rearrangements in the genome of the green-veined white butterfly (Pieris napi, Pieridae, Linnaeus, 1758). This unprecedented reshuffling is cryptic: microsynteny and chromosome number do not indicate the extensive rearrangement revealed by a chromosome level assembly and high-resolution linkage map.Furthermore, the rearrangement blocks themselves appear to be non-random, as they are significantly enriched for clustered groups of functionally annotated genes revealing that the evolutionary dynamics acting on Lepidopteran genome structure are more complex than previously envisioned.

Correspondence to: AW alyssa.woronik@zoologi.su.se and CWW chris.wheat@zoologi.su.se 20 21 Tradeoffs affect resource allocation during development and result in fitness consequences that 22 drive the evolution of life history strategies. Yet despite their importance, we know little about 23 the mechanisms underlying life history tradeoffs in wild populations. Many species of Colias 24 butterflies exhibit an alternative life history strategy (ALHS) where females divert resources from 25 wing pigment synthesis to reproductive and somatic development. Due to this reallocation, a 26 wing color polymorphism is associated with the ALHS: individuals have either yellow/orange or 27 white wings. Here we map the genetic basis of the ALHS switch in Colias crocea to a 28 transposable element insertion downstream of the Colias homolog of BarH-1, a homeobox 29 transcription factor. Using CRISPR/Cas9 gene editing, antibody staining, and electron 30 microscopy we find morph-specific specific expression of BarH-1 suppresses the formation of 31 pigment granules in wing scales. Lipid and transcriptome analyses reveal physiological 32 differences associated with the ALHS. These findings characterize a novel mechanism for a 33 female-limited ALHS and show that the switch arises via recruitment of a transcription factor 34 previously known for its function in cell fate determination in pigment cells of the retina. 35 36A life-history strategy is a complex pattern of co-evolved life history traits (e.g. number of 37 offspring, size of offspring, and lifespan 1 ), that is fundamentally shaped by tradeoffs that arise 38 because all fitness components cannot simultaneously be maximized. Therefore, finite 39 resources are competitively allocated to one life history trait versus another within a single 40 individual, and selection acts on these allocation patterns to optimize fitness 2 . Evolutionary 41 theory predicts that positive selection will remove variation from natural populations, as 42 genotypes with the highest fitness go to fixation 3 . However, across diverse taxa alternative life 43 history strategies (ALHSs) are maintained within populations at intermediate frequencies due to 44 balancing selection 4 . Life history theory was developed using methods such as quantitative 45 genetics, artificial selection, demography, and modeling to gain significant insights into the 46 causes and consequences of genetic and environmental variation on life history traits. Yet 47 despite these advances, a key challenge that remains is to identify the proximate mechanisms 48 underlying tradeoffs, especially for ecologically relevant tradeoffs that occur in natural 49 populations 5 . Here, we identify the mechanism underlying one such ALHS in the butterfly Colias 50

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