A complete time-calibrated multi-gene phylogeny of the European butterflies

A macroevolutionary role for chromosomal fusion and fission in Erebia butterflies

The impact of large-scale chromosomal rearrangements, such as fusions and fissions, on speciation is a long-standing conundrum. We assessed whether bursts of change in chromosome numbers resulting from chromosomal fusion or fission are related to increased speciation rates in Erebia, one of the most species-rich and karyotypically variable butterfly groups. We established a genome-based phylogeny and used state-dependent birth-death models to infer trajectories of karyotype evolution. We demonstrated that rates of anagenetic chromosomal changes (i.e., along phylogenetic branches) exceed cladogenetic changes (i.e., at speciation events), but, when cladogenetic changes occur, they are mostly associated with chromosomal fissions rather than fusions. We found that the relative importance of fusion and fission differs among Erebia clades of different ages and that especially in younger, more karyotypically diverse clades, speciation is more frequently associated with cladogenetic chromosomal changes. Overall, our results imply that chromosomal fusions and fissions have contrasting macroevolutionary roles and that large-scale chromosomal rearrangements are associated with bursts of species diversification.

Chromosome-Level Assembly and Annotation of the Pearly Heath Coenonympha arcania Butterfly Genome

We present the first chromosome-level genome assembly and annotation of the pearly heath Coenonympha arcania, generated with a PacBio HiFi sequencing approach and complemented with Hi-C data. We additionally compare synteny, gene, and repeat content between C. arcania and other Lepidopteran genomes. This reference genome will enable future population genomics studies with Coenonympha butterflies, a species-rich genus that encompasses some of the most highly endangered butterfly taxa in Europe.

A Chromosome-Level Genome Assembly and Annotation for the Clouded Apollo Butterfly (Parnassius mnemosyne): A Species of Global Conservation Concern

The clouded apollo (Parnassius mnemosyne) is a palearctic butterfly distributed over a large part of western Eurasia, but population declines and fragmentation have been observed in many parts of the range. The development of genomic tools can help to shed light on the genetic consequences of the decline and to make informed decisions about direct conservation actions. Here, we present a high-contiguity, chromosome-level genome assembly of a female clouded apollo butterfly and provide detailed annotations of genes and transposable elements. We find that the large genome (1.5 Gb) of the clouded apollo is extraordinarily repeat rich (73%). Despite that, the combination of sequencing techniques allowed us to assemble all chromosomes (nc = 29) to a high degree of completeness. The annotation resulted in a relatively high number of protein-coding genes (22,854) compared with other Lepidoptera, of which a large proportion (21,635) could be assigned functions based on homology with other species. A comparative analysis indicates that overall genome structure has been largely conserved, both within the genus and compared with the ancestral lepidopteran karyotype. The high-quality genome assembly and detailed annotation presented here will constitute an important tool for forthcoming efforts aimed at understanding the genetic consequences of fragmentation and decline, as well as for assessments of genetic diversity, population structure, inbreeding, and genetic load in the clouded apollo butterfly.

Phylogeography of Two Enigmatic Sulphur Butterflies, Colias mongola Alphéraky, 1897 and Colias tamerlana Staudinger, 1897 (Lepidoptera, Pieridae), with Relations to Wolbachia Infection

The genus Colias Fabricius, 1807 includes numerous taxa and forms with uncertain status and taxonomic position. Among such taxa are Colias mongola Alphéraky, 1897 and Colias tamerlana Staudinger, 1897, interpreted in the literature either as conspecific forms, as subspecies of different but morphologically somewhat similar Colias species or as distinct species-level taxa. Based on mitochondrial and nuclear DNA markers, we reconstructed a phylogeographic pattern of the taxa in question. We recover and include in our analysis DNA barcodes of the century-old type specimens, the lectotype of C. tamerlana deposited in the Natural History Museum (Museum für Naturkunde), Berlin, Germany (ZMHU) and the paralectotype of C. tamerlana and the lectotype of C. mongola deposited in the Zoological Institute, Russian Academy of Sciences, St. Petersburg, Russia (ZISP). Our analysis grouped all specimens within four (HP_I-HP_IV) deeply divergent but geographically poorly structured clades which did not support nonconspecifity of C. mongola-C. tamerlana. We also show that all studied females of the widely distributed haplogroup HP_II were infected with a single Wolbachia strain belonging to the supergroup B, while the males of this haplogroup, as well as all other investigated specimens of both sexes, were not infected. Our data highlight the relevance of large-scale sampling dataset analysis and the need for testing for Wolbachia infection to avoid erroneous phylogenetic reconstructions and species misidentification.

Day-flying lepidoptera larvae have a poorer ability to thermoregulate than adults

Changes to ambient temperatures under climate change may detrimentally impact small ectotherms that rely on their environment for thermoregulation; however, there is currently a limited understanding of insect larval thermoregulation. As holometabolous insects, Lepidoptera differ in morphology, ecology and behaviour across the life cycle, and so it is likely that adults and larvae differ in their capacity to thermoregulate. In this study, we investigated the thermoregulatory capacity (buffering ability) of 14 species of day-flying Lepidoptera, whether this is influenced by body length or gregariousness, and whether it differs between adult and larval life stages. We also investigated what thermoregulation mechanisms are used: microclimate selection (choosing locations with a particular temperature) or behavioural thermoregulation (controlling temperature through other means, such as basking). We found that Lepidoptera larvae differ in their buffering ability between species and body lengths, but gregariousness did not influence buffering ability. Larvae are worse at buffering themselves against changes in air temperature than adults. Therefore Lepidoptera may be more vulnerable to adverse temperature conditions during their larval life stage. Adults and larvae rely on different thermoregulatory mechanisms; adults primarily use behavioural thermoregulation, whereas larvae use microclimate selection. This implies that larvae are highly dependent on the area around their foodplant for effective thermoregulation. These findings have implications for the management of land and species, for example, highlighting the importance of creating and preserving microclimates and vegetation complexity surrounding Lepidoptera foodplants for larval thermoregulation under future climate change.

Tempo and Mode of Genome Structure Evolution in Insects

The division of the genome into discrete chromosomes is a fundamental characteristic of eukaryotic life. Insect taxonomists' early adoption of cytogenetics has led to an incredible amount of data describing genome structure across insects. In this article, we synthesize data from thousands of species and use biologically realistic models to infer the tempo and mode of chromosome evolution among insect orders. Our results show that orders vary dramatically in the overall rate of chromosome number evolution (a proxy of genome structural stability) and the pattern of evolution (e.g., the balance between fusions and fissions). These findings have important implications for our understanding of likely modes of speciation and offer insight into the most informative clades for future genome sequencing.

Assessing the aesthetic attractivity of European butterflies: A web-based survey protocol

Aesthetic attractivity stands as an underestimated yet fundamental feature of species in conservation biology, significantly driving disproportionate protection efforts towards charismatic species. Despite the evidence, few attempts sought to precisely quantify the impact of aesthetic attractivity in defining priority of species for conservation actions (e.g. inclusion in International Union for Conservation of Nature red lists and protection lists). This study protocol describes the setting of an online test (available from April 2022 to April 2023 at www.unveiling.eu) designed to i) quantify the aesthetic attractivity to humans of the 496 European butterfly species and ii) identify which features (both in the perceived animal and in the perceiver) influence the aesthetic attractivity of a given butterfly species. The test is divided in 5 sections (personal data, ranking, single morphological features, emotional engagement, dispositional variables) aimed at profiling the relation each participant has with the species examined. In the long-term, evaluating butterflies' aesthetic attractivity could facilitate the critical assessment of current conservation strategies, such as the process of selection of flag and umbrella species by research institutions, environmental associations and Non Governative Organizations. This is expected to provide the much-needed evidence to set up unbiased biodiversity conservation strategies and counteract the selective anthropogenic pressure which favours the extinction of unattractive species, being no or less protected compared to charismatic species.

Molecular Phylogeny and Taxonomy of the Butterfly Subtribe Scolitantidina with Special Focus on the Genera Pseudophilotes, Glaucopsyche and Iolana (Lepidoptera, Lycaenidae)

The Palearctic blue butterfly genus Pseudophilotes Beuret, 1958 is not homogenous regarding the morphology of its genital structures. For this reason, some of its species have been considered to be representatives of other genera of the subtribe Scolitantidina (subfamily Polyommatinae). Here, we address these taxonomic problems by analyzing the phylogenetic relationships between the genera, subgenera, and species of this subtribe inferred via the analysis of five nuclear and two mitochondrial DNA sequences. We demonstrate that the enigmatic Asian species P. panope (Eversmann, 1851) belongs to the genus Pseudophilotes but not to Praephilotes Forster, 1938 or Palaeophilotes Forster, 1938 and does not represent the independent genus Inderskia Korshunov, 2000, as hypothesized previously. We synonymize P. svetlana Yakovlev, 2003 (syn. nov.) and P. marina Zhdanko, 2004 (syn. nov.) with P. panope. We demonstrate a deep genetic divergence between lineages that were previously considered as subspecies of the single species Iolana iolas (Ochsenheimer, 1816). As a result, we confirm the multispecies concept of the genus Iolana Bethune-Baker, 1914. We show that the Holarctic genus Glaucopsyche can be divided into four subgenera: Glaucopsyche Scudder, 1872 (=Shijimiaeoides Beuret, 1958), Apelles Hemming, 1931, Bajluana Korshunov and Ivonin, 1990, and Phaedrotes Scudder, 1876.

Modeling the extinction risk of European butterflies and odonates

Insect populations have become increasingly threatened during the last decades due to climate change and landuse intensification. Species characteristics driving these threats remain poorly understood. Trait‐based analyses provide a straight‐forward approach to gain a mechanistic understanding of species' extinction risk, guiding the development of conservation strategies. We combined morphological traits and phylogenetic relationship for 332 European species of butterflies and 115 species of odonates (dragon and damselflies) to model their red list status via phylogenetically controlled ordered logistic regression. We hypothesized that extinction risk increases with increasing body volume and wing area, decreasing range size, and is larger for brighter species. All investigated traits exhibited a strong phylogenetic signal. When controlling for phylogenetic relationship, we found that extinction risk of butterflies increased with decreasing range size. The extinction risk of odonates showed no relationship with the selected traits. Our results show that there is no universal trait defining the extinction risk of our investigated insect taxa. Furthermore, evolutionary history, measured as the phylogenetically predicted part of our analyzed traits, poorly predicted extinction risk. Our study confirms the focus of conservation measures on European butterfly species with small range sizes.

Climate, immigration and speciation shape terrestrial and aquatic biodiversity in the European Alps

Quaternary climate fluctuations can affect speciation in regional biodiversity assembly in two non-mutually exclusive ways: a glacial species pump, where isolation in glacial refugia accelerates allopatric speciation, and adaptive radiation in underused adaptive zones during ice-free periods. We detected biogeographic and genetic signatures associated with both mechanisms in the assembly of the biota of the European Alps. Age distributions of endemic and widespread species within aquatic and terrestrial taxa (amphipods, fishes, amphibians, butterflies and flowering plants) revealed that endemic fish evolved only in lakes, are highly sympatric, and mainly of Holocene age, consistent with adaptive radiation. Endemic amphipods are ancient, suggesting preglacial radiation with limited range expansion and local Pleistocene survival, perhaps facilitated by a groundwater-dwelling lifestyle. Terrestrial endemics are mostly of Pleistocene age and are thus more consistent with the glacial species pump. The lack of evidence for Holocene adaptive radiation in the terrestrial biome is consistent with faster recolonization through range expansion of these taxa after glacial retreats. More stable and less seasonal ecological conditions in lakes during the Holocene may also have contributed to Holocene speciation in lakes. The high proportion of young, endemic species makes the Alpine biota vulnerable to climate change, but the mechanisms and consequences of species loss will likely differ between biomes because of their distinct evolutionary histories.

Phenological sensitivity and seasonal variability explain climate-driven trends in Mediterranean butterflies

Although climate-driven phenological shifts have been documented for many taxa across the globe, we still lack knowledge of the consequences they have on populations. Here, we used a comprehensive database comprising 553 populations of 51 species of north-western Mediterranean butterflies to investigate the relationship between phenology and population trends in a 26-year period. Phenological trends and sensitivity to climate, along with various species traits, were used to predict abundance trends. Key ecological traits accounted for a general decline of more than half of the species, most of which, surprisingly, did not change their phenology under a climate warming scenario. However, this was related to the regional cooling in a short temporal window that includes late winter and early spring, during which most species concentrate their development. Finally, we demonstrate that phenological sensitivity—but not phenological trends—predicted population trends, and argue that species that best adjust their phenology to inter-annual climate variability are more likely to maintain a synchronization with trophic resources, thereby mitigating possible negative effects of climate change. Our results reflect the importance of assessing not only species' trends over time but also species’ abilities to respond to a changing climate based on their sensitivity to temperature.

Pronounced mito-nuclear discordance and various Wolbachia infections in the water ringlet Erebia pronoe have resulted in a complex phylogeographic structure

Several morphological and mitochondrial lineages of the alpine ringlet butterfly species Erebia pronoe have been described, indicating a complex phylogenetic structure. However, the existing data were insufficient and allow neither a reconstruction of the biogeographic history, nor an assessment of the genetic lineages. Therefore, we analysed mitochondrial (COI, NDI) and nuclear (EF1α, RPS5) gene sequences and compared them with sequences from the sister species Erebia melas. Additionally, we combined this information with morphometric data of the male genitalia and the infection patterns with Wolbachia strains, based on a WSP analysis. We obtained a distinct phylogeographic structure within the E. pronoe-melas complex with eight well-distinguishable geographic groups, but also a remarkable mito-nuclear discordance. The mito-nuclear discordance in E. melas and E. pronoe glottis can be explained by different ages of Wolbachia infections with different Wolbachia strains, associated selective sweeps, and hybridisation inhibition. Additionally, we found indications for incipient speciation of E. pronoe glottis in the Pyrenees and a pronounced range dynamic within and among the other high mountain systems of Europe. Our results emphasize the importance of combined approaches in reconstructing biogeographic patterns and evaluating phylogeographic splits.

Hybridization fuelled diversification in Spialia butterflies

The importance of hybridization and introgression is well documented in the evolution of plants but, in insects, their role is not fully understood. Given the fact that insects are the most diverse group of organisms, assessing the impact of reticulation events on their evolution may be key to comprehend the emergence of such remarkable diversity. Here, we used an insect model, the Spialia butterflies, to gather genomic evidence of hybridization as a promoter of novel diversity. By using double‐digest RADseq (ddRADseq), we explored the phylogenetic relationships between Spialia orbifer, S. rosae and S. sertorius, and documented two independent events of interspecific gene flow. Our data support that the Iberian endemism S. rosae probably received genetic material from S. orbifer in both mitochondrial and nuclear DNA, which could have contributed to a shift in the ecological preferences of S. rosae. We also show that admixture between S. sertorius and S. orbifer probably occurred in Italy. As a result, the admixed Sicilian populations of S. orbifer are differentiated from the rest of populations both genetically and morphologically, and display signatures of reproductive character displacement in the male genitalia. Additionally, our analyses indicated that genetic material from S. orbifer is present in S. sertorius along the Italian Peninsula. Our findings add to the view that hybridization is a pervasive phenomenon in nature and in butterflies in particular, with important consequences for evolution due to the emergence of novel phenotypes.

A supertree of Northern European macromoths

Ecological and life-history data on the Northern European macromoth (Lepidoptera: Macroheterocera) fauna is widely available and ideal for use in answering phylogeny-based research questions: for example, in comparative biology. However, phylogenetic information for such studies lags behind. Here, as a synthesis of all currently available phylogenetic information on the group, we produce a supertree of 114 Northern European macromoth genera (in four superfamilies, with Geometroidea considered separately), providing the most complete phylogenetic picture of this fauna available to date. In doing so, we assess those parts of the phylogeny that are well resolved and those that are uncertain. Furthermore, we identify those genera for which phylogenetic information is currently too poor to include in such a supertree, or entirely absent, as targets for future work. As an aid to studies involving these genera, we provide information on their likely positions within the macromoth tree. With phylogenies playing an ever more important role in the field, this supertree should be useful in informing future ecological and evolutionary studies.

Migrators within migrators: exploring transposable element dynamics in the monarch butterfly, Danaus plexippus

Background

Lepidoptera (butterflies and moths) are an important model system in ecology and evolution. A high-quality chromosomal genome assembly is available for the monarch butterfly (Danaus plexippus), but it lacks an in-depth transposable element (TE) annotation, presenting an opportunity to explore monarch TE dynamics and the impact of TEs on shaping the monarch genome.

Results

We find 6.21% of the monarch genome is comprised of TEs, a reduction of 6.85% compared to the original TE annotation performed on the draft genome assembly. Monarch TE content is low compared to two closely related species with available genomes, Danaus chrysippus (33.97% TE) and Danaus melanippus (11.87% TE). The biggest TE contributions to genome size in the monarch are LINEs and Penelope-like elements, and three newly identified families, r2-hero_dPle (LINE), penelope-1_dPle (Penelope-like), and hase2-1_dPle (SINE), collectively contribute 34.92% of total TE content. We find evidence of recent TE activity, with two novel Tc1 families rapidly expanding over recent timescales (tc1-1_dPle, tc1-2_dPle). LINE fragments show signatures of genomic deletions indicating a high rate of TE turnover. We investigate associations between TEs and wing colouration and immune genes and identify a three-fold increase in TE content around immune genes compared to other host genes.

Conclusions

We provide a detailed TE annotation and analysis for the monarch genome, revealing a considerably smaller TE contribution to genome content compared to two closely related Danaus species with available genome assemblies. We identify highly successful novel DNA TE families rapidly expanding over recent timescales, and ongoing signatures of both TE expansion and removal highlight the dynamic nature of repeat content in the monarch genome. Our findings also suggest that insect immune genes are promising candidates for future interrogation of TE-mediated host adaptation.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13100-022-00263-5.

Phylogeny, species delimitation and biogeography of the endemic Palaearctic tribe Tomarini (Lepidoptera: Lycaenidae)

The tribe Tomarini is represented by the sole genus Tomares, comprising about eight species distributed from the western Mediterranean to Central Asia. We carried out a multilocus phylogenetic and a biogeographical analysis to test the taxonomy of the genus by several molecular species delimitation methods and reveal patterns shaping the current distribution of Tomares. The phylogenetic analysis based on four molecular markers recovered the monophyly of the genus and recovered two deep-branching lineages: an African clade and an Asian clade. Species delimitation analyses suggested six or ten putative species depending on the method applied. The haplotype network analysis of the Tomares nogelii clade revealed no phylogeographical and taxonomic structure. We consider the taxon Tomares nesimachus (syn. nov.) a synonym of T. nogelii and reinstate Tomares callimachus dentata stat. rev. for populations from south-eastern Turkey. Tomares originated between the early Oligocene and the early Miocene, most probably in south-west Asia. The split of the most recent common ancestor of Tomares occurred between the middle-late Miocene and middle-late Pliocene, probably as a response to increasing aridification and habitat fragmentation. Differentiation of the Asian clade took place in south-west Asia during the Pliocene and Pleistocene and coincided temporally with the evolution of Tomares host plants of the genus Astragalus (Fabaceae).

Molecular and morphological evidence reveals a new genus of the subfamily Heteropterinae (Lepidoptera, Hesperiidae) from China

Molecular phylogenetic analysis indicates that the genus Carterocephalus is not monophyletic. Based on combined molecular and morphological evidence, we propose a new genus, Pulchroptera Hou, Fan & Chiba, gen. nov., for Pamphilapulchra Leech, 1891. The adult, wing venation, and male genitalia of Pulchropterapulchra comb. nov., Carterocephaluspalaemon, and related genera are illustrated.

Climate change drives mountain butterflies towards the summits

Climate change impacts biodiversity and is driving range shifts of species and populations across the globe. To understand the effects of climate warming on biota, long-term observations of the occurrence of species and detailed knowledge on their ecology and life-history is crucial. Mountain species particularly suffer under climate warming and often respond to environmental changes by altitudinal range shifts. We assessed long-term distribution trends of mountain butterflies across the eastern Alps and calculated species' specific annual range shifts based on field observations and species distribution models, counterbalancing the potential drawbacks of both approaches. We also compiled details on the ecology, behaviour and life-history, and the climate niche of each species assessed. We found that the highest altitudinal maxima were observed recently in the majority of cases, while the lowest altitudes of observations were recorded before 1980. Mobile and generalist species with a broad ecological amplitude tended to move uphill more than specialist and sedentary species. As main drivers we identified climatic conditions and topographic variables, such as insolation and solar irradiation. This study provides important evidence for responses of high mountain taxa to rapid climate change. Our study underlines the advantage of combining historical surveys and museum collection data with cutting-edge analyses.

Population genomics reveals variable patterns of immune gene evolution in monarch butterflies (Danaus plexippus)

Humoral and cellular immune responses provide animals with major defences against harmful pathogens. While it is often assumed that immune genes undergo rapid diversifying selection, this assumption has not been tested in many species. Moreover, it is likely that different classes of immune genes experience different levels of evolutionary constraint, resulting in varying selection patterns. We examined the evolutionary patterns for a set of 91 canonical immune genes of North American monarch butterflies (Danaus plexippus), using as an outgroup the closely related soldier butterfly (Danaus eresimus). As a comparison to these immune genes, we selected a set of control genes that were paired with each immune for approximate size and genomic location. As a whole, these immune genes had a significant but modest reduction in Tajima's D relative to paired-control genes, but otherwise did not show distinct patterns of population genetic variation or evolutionary rates. When further partitioning these immune genes into four functional classes (recognition, signalling, modulation, and effector), we found distinct differences among these groups. Relative to control genes, recognition genes exhibit increased nonsynonymous diversity and divergence, suggesting reduced constraints on evolution, and supporting the notion that coevolution with pathogens results in diversifying selection. In contrast, signalling genes showed an opposite pattern of reduced diversity and divergence, suggesting evolutionary constraints and conservation. Modulator and effector genes showed no statistical differences from controls. These results are consistent with patterns found in immune genes in fruit flies and Pieris butterflies, suggesting that consistent selective pressures on different classes of immune genes broadly govern the evolution of innate immunity among insects.

Great chemistry between us: The link between plant chemical defenses and butterfly evolution

Plants constantly cope with insect herbivory, which is thought to be the evolutionary driver for the immense diversity of plant chemical defenses. Herbivorous insects are in turn restricted in host choice by the presence of plant chemical defense barriers. In this study, we analyzed whether butterfly host-plant patterns are determined by the presence of shared plant chemical defenses rather than by shared plant evolutionary history. Using correlation and phylogenetic statistics, we assessed the impact of host-plant chemical defense traits on shaping northwestern European butterfly assemblages at a macroevolutionary scale. Shared chemical defenses between plant families showed stronger correlation with overlap in butterfly assemblages than phylogenetic relatedness, providing evidence that chemical defenses may determine the assemblage of butterflies per plant family rather than shared evolutionary history. Although global congruence between butterflies and host-plant families was detected across the studied herbivory interactions, cophylogenetic statistics showed varying levels of congruence between butterflies and host chemical defense traits. We attribute this to the existence of multiple antiherbivore traits across plant families and the diversity of insect herbivory associations per plant family. Our results highlight the importance of plant chemical defenses in community ecology through their influence on insect assemblages.

Climate predicts both visible and near-infrared reflectance in butterflies

Climatic gradients frequently predict large-scale ecogeographical patterns in animal coloration, but the underlying causes are often difficult to disentangle. We examined ecogeographical patterns of reflectance among 343 European butterfly species and isolated the role of selection for thermal benefits by comparing animal-visible and near-infrared (NIR) wavebands. NIR light accounts for ~50% of solar energy but cannot be seen by animals so functions primarily in thermal control. We found that reflectance of both dorsal and ventral surfaces shows thermally adaptive correlations with climatic factors including temperature and precipitation. This adaptive variation was more prominent in NIR than animal-visible wavebands and for body regions (thorax-abdomen and basal wings) that are most important for thermoregulation. Thermal environments also predicted the reflectance difference between dorsal and ventral surfaces, which may be due to modulation between requirements for heating and cooling. These results highlight the importance of climatic gradients in shaping the reflectance properties of butterflies at a continent-wide scale.

Large-scale comparative analysis of cytogenetic markers across Lepidoptera

Fluorescence in situ hybridization (FISH) allows identification of particular chromosomes and their rearrangements. Using FISH with signal enhancement via antibody amplification and enzymatically catalysed reporter deposition, we evaluated applicability of universal cytogenetic markers, namely 18S and 5S rDNA genes, U1 and U2 snRNA genes, and histone H3 genes, in the study of the karyotype evolution in moths and butterflies. Major rDNA underwent rather erratic evolution, which does not always reflect chromosomal changes. In contrast, the hybridization pattern of histone H3 genes was well conserved, reflecting the stable organisation of lepidopteran genomes. Unlike 5S rDNA and U1 and U2 snRNA genes which we failed to detect, except for 5S rDNA in a few representatives of early diverging lepidopteran lineages. To explain the negative FISH results, we used quantitative PCR and Southern hybridization to estimate the copy number and organization of the studied genes in selected species. The results suggested that their detection was hampered by long spacers between the genes and/or their scattered distribution. Our results question homology of 5S rDNA and U1 and U2 snRNA loci in comparative studies. We recommend the use of histone H3 in studies of karyotype evolution.

The Pleistocene species pump past its prime: Evidence from European butterfly sister species

The Pleistocene glacial cycles had a profound impact on the ranges and genetic make-up of organisms. While it is clear that the contact zones that have been described for many sister taxa are secondary and have formed in the current interglacial, it is unclear when the taxa involved began to diverge. Previous estimates based on small numbers of loci are unreliable given the stochasticity of genetic drift and the contrasting effects of incomplete lineage sorting and gene flow on gene divergence. Here, we use genome-wide transcriptome data to estimate divergence for 18 sister species pairs of European butterflies showing either sympatric or contact zone distributions. We find that in most cases, species divergence predates the mid-Pleistocene transition or even the entire Pleistocene period. We also show that although post-divergence gene flow is restricted to contact zone pairs, they are not systematically younger than sympatric pairs. This suggests that contact zones are not limited to the initial stages of the speciation process, but can involve notably old taxa. Finally, we show that mitochondrial divergence and nuclear divergence are only weakly correlated and mitochondrial divergence is higher for contact zone pairs.

Genomics-guided refinement of butterfly taxonomy

Continuing with comparative genomic exploration of worldwide butterfly fauna, we use all protein-coding genes as they are retrieved from the whole genome shotgun sequences for phylogeny construction. Analysis of these genome-scale phylogenies projected onto the taxonomic classification and the knowledge about butterfly phenotypes suggests further refinements of butterfly taxonomy that are presented here. As a general rule, we assign most prominent clades of similar genetic differentiation to the same taxonomic rank, and use criteria based on relative population diversification and the extent of gene exchange for species delimitation. As a result, 7 tribes, 4 subtribes, 14 genera, and 9 subgenera are proposed as new, i.e., in subfamily Pierinae Swainson, 1820: Calopierini Grishin, trib. n. (type genus Calopieris Aurivillius, 1898); in subfamily Riodininae Grote, 1895: Callistiumini Grishin, trib. n. (type genus Callistium Stichel, 1911); in subfamily Nymphalinae Rafinesque, 1815: Pycinini Grishin, trib. n. (type genus Pycina Doubleday 1849), Rhinopalpini Grishin, trib. n. (type genus Rhinopalpa C. & R. Felder 1860), Kallimoidini Grishin, trib. n. (type genus Kallimoides Shirôzu & Nakanishi 1984), Vanessulini Grishin, trib. n. (type genus Vanessula Dewitz 1887), and Doleschalliaini Grishin, trib. n. (type genus Doleschallia C. & R. Felder 1860); in tribe Mesosemiini Bates, 1859: Eunogyrina Grishin, subtrib. n. (type genus Eunogyra Westwood, 1851); in tribe Satyrini Boisduval, 1833: Callerebiina Grishin, subtrib. n. (type genus Callerebia Butler, 1867), Gyrocheilina Grishin, subtrib. n. (type genus Gyrocheilus Butler, 1867), and Calistina Grishin, subtrib. n. (type genus Calisto Hübner, [1823]); in subfamily Euselasiinae Kirby, 1871: Pelolasia Grishin, gen. n. (type species Eurygona pelor Hewitson, [1853]), Myselasia Grishin, gen. n. (type species Eurygona mys Herrich-Schäffer, [1853]), Eurylasia Grishin, gen. n. (type species Eurygona euryone Hewitson, 1856), Maculasia Grishin, gen. n. (type species Euselasia albomaculiga Callaghan, 1999), and Eugelasia Grishin, gen. n. (type species Eurygona eugeon Hewitson, 1856); in subtribe Mesosemiina Bates, 1859: Ectosemia Grishin, gen. n. (type species Papilio eumene Cramer, 1776) and Endosemia Grishin, gen. n. (type species Papilio ulrica Cramer, 1777); in tribe Symmachiini Reuter, 1896: Tigria Grishin, gen. n. (type species Mesene xypete Hewitson, 1870) and Asymma Grishin, gen. n. (type species Symmachia virgatula Stichel, 1910); in tribe Riodinini Grote, 1895: Putridivora Grishin, gen. n. (type species Charis argyrea Bates, 1868), Chadia Grishin, gen. n. (type species Charis cadytis Hewitson, 1866), Inkana Grishin, gen. n. (type species Charis incoides Schaus, 1902), and Oco Grishin, gen. n. (type species Symmachia ocellata Hewitson, 1867); in subtribe Zabuellina Seraphim, Freitas & Kaminski, 2018: Teenie Grishin, gen. n. (type species Calydna tinea Bates, 1868); Boreographium Grishin, subgen. n. (type species Papilio marcellus Cramer, 1777, parent genus Eurytides Hübner, [1821]), Esperourus Grishin, subgen. n. (type species Papilio esperanza Beutelspacher, 1975, parent genus Pterourus Scopoli, 1777), Hyppasonia Grishin, subgen. n. (type species Papilio hyppason Cramer, 1775, parent genus Heraclides Hübner, [1819]), Sisymbria Grishin, subgen. n. (type species Pieris sisymbrii Boisduval, 1852, parent genus Pontia [Fabricius], 1807), Greenie Grishin, subgen. n. (type species Thecla sheridonii [sic] Edwards, 1877, parent genus Callophrys Billberg, 1820), Magda Grishin, subgen. n. (type species Erebia magdalena Strecker, 1880, parent genus Erebia Dalman, 1816), and in genus Eresia Boisduval, 1836: Notilia Grishin, subgen. n. (type species Eresia orthia Hewitson, 1864), Levinata Grishin, subgen. n. (type species Eresia levina Hewitson, 1872), and Ithra Grishin, subgen. n. (type species Phyciodes ithra Kirby, 1900). Furthermore, we resurrect 6 genera, change the rank of 36 currently used genera to subgenus, synonymize 3 subtribes, 42 genera or subgenera, assign 3 genera to tribes and subtribes, and transfer 34 additional species to genera different from those these taxa are presently assigned to, present evidence to support 7 taxa as species instead of subspecies, and 1 taxon as a subspecies instead of species. Namely, the following taxa are valid genera: Terias Swainson, 1821 (not in Eurema Hübner, [1819]), Erythia Hübner, [1819] and Marmessus Hübner, [1819] (not in Euselasia Hübner, [1819]), Eucorna Strand, 1932 (not in Voltinia Stichel, 1910), Cremna Doubleday, 1847 (not in Napaea Hübner, [1819]), and Hallonympha Penz & DeVries, 2006 (not in Zabuella Stichel, 1911). The following taxa are best treated as subgenera: Zegris Boisduval, 1836 of Anthocharis Boisduval, Rambur, [Duménil] & Graslin, [1833]; Baltia Moore, 1878 and Pontieuchloia Verity, 1929 of Pontia [Fabricius], 1807; Phrissura Butler, 1870 of Appias Hübner, [1819]; Saletara Distant, 1885 of Catophaga Hübner, 1819; Leodonta Butler, 1870 of Pereute Herrich-Schäffer, 1867; Takashia M. Okano & T. Okano, 1985 of Polycaena Staudinger, 1886; Corrachia Schaus, 1913 of Styx Staudinger, 1876; Ionotus Hall, 2005 and Voltinia Stichel, 1910 of Cremna Doubleday, 1847; Hermathena Hewitson, 1874 of Ithomiola C. & R. Felder, 1865; Lucillella Strand, 1932 of Esthemopsis C. & R. Felder, 1865; Mesenopsis Godman & Salvin, 1886 and Xenandra C. & R. Felder, 1865 of Symmachia Hübner, [1819]; Pirascca J. Hall & Willmott, 1996 of Pterographium Stichel, 1910; Imelda Hewitson, 1870 of Echenais Hübner, [1819]; Calicosama J. Hall & Harvey, 2001 of Behemothia Hall, 2000; Polygrapha Staudinger, 1887 and Fountainea Rydon, 1971 of Anaea Hübner, [1819]; Siderone Hübner, [1823] and Phantos Dias, 2018 of Zaretis Hübner, [1819]; Harsiesis Fruhstorfer, 1911 of Platypthima Rothschild & Jordan, 1905; Vila Kirby, 1871 of Biblis Fabricius, 1807; Diaethria Billberg, 1820 and Perisama Doubleday, 1849 of Callicore Hübner, [1819]; Antigonis C. Felder, 1861 of Haematera Doubleday, 1849; Asterope Hübner, [1819], Nica Hübner, [1826], Peria Kirby, 1871, and Callicorina Smart, 1976 of Temenis Hübner, [1819]; Anthanassa Scudder, 1875, Castilia Higgins, 1981, Telenassa Higgins, 1981, Dagon Higgins, 1981, and Janatella Higgins, 1981 of Eresia Boisduval, 1836; and Wallengrenia Berg, 1897 of Polites Scudder, 1872. The following taxa are junior subjective synonyms: Maniolina Grote, 1897 of Erebiina Tutt, 1896; Melanargiina Wheeler, 1903 of Satyrina Boisduval, 1833; Phyciodina Higgins, 1981 of Melitaeina Herrich-Schäffer, 1843; Cunizza Grote, 1900 of Hesperocharis C. Felder, 1862; Reliquia Ackery, 1975 of Pontia [Fabricius], 1807; Tatochila A. Butler, 1870, Piercolias Staudinger, 1894, Hypsochila Ureta, 1955, Theochila W. D. Field, 1958, Pierphulia W. D. Field, 1958, and Infraphulia W. D. Field, 1958 of Phulia Herrich-Schäffer, 1867; Mesapia Gray, 1856 of Aporia Hübner, [1819]; Catasticta Butler, 1870 of Archonias Hübner, 1827; Sandia Clench & P. Ehrlich, 1960 andXamia Clench, 1961 of Incisalia Scudder, 1872; Hades Westwood, 1851 of Methone Doubleday, 1847; Semomesia Westwood, 1851, Mesophthalma Westwood, 1851, Perophthalma Westwood, 1851 and Leucochimona Stichel, 1909 of Mesosemia Hübner, [1819], Xynias Hewitson, 1874 of Mesenopsis Godman & Salvin, 1886; Stichelia J. Zikán, 1949 of Symmachia Hübner, [1819]; Chimastrum Godman & Salvin, 1886 of Mesene Doubleday, 1847; Alethea Nielsen & Salazar, [2018] of Pirascca J. Hall & Willmott, 1996; Panaropsis J. Hall, 2002 of Pterographium Stichel, 1910; Comphotis Stichel, 1910 of Phaenochitonia Stichel, 1910; Colaciticus Stichel, 1910 of Baeotis Hübner, [1819]; Nahida Kirby, 1871 of Ithomeis Bates, 1862; Machaya Hall & Willmott, 1995 of Pachythone Bates, 1868; Percnodaimon Butler, 1876 and Erebiola Fereday, 1879 of Argyrophenga Doubleday, 1845; Hestinalis Bryk, 1938 of Mimathyma Moore, 1896; Catacore Dillon, 1948 of Diaethria Billberg, 1820; Mesotaenia Kirby, 1871 and Orophila Staudinger, 1886 of Perisama Doubleday, 1849; Paulogramma Dillon, 1948 of Catagramma Boisduval, 1836; Panacea Godman & Salvin, 1883 of Batesia C. Felder & R. Felder, 1862; Napeocles Bates, 1864 of Siproeta Hübner, [1823]; Texola Higgins, 1959 and Dymasia Higgins, 1960 of Microtia H. Bates, 1864; Tisona Higgins, 1981 of Ortilia Higgins, 1981; Abananote Potts, 1943 and Altinote Potts, 1943 of Actinote Hübner, [1819]; Episcada Godman & Salvin, 1879 of Ceratinia Hübner, 1816; and Appia Evans, 1955 of Pompeius Evans, 1955. The following genera are placed in taxonomic hierarchy: Prestonia Schaus, 1920 belongs to Euremini Grote, 1898; Petrocerus Callaghan, 1979 belongs to Theopina Clench, 1955; and Paralasa Moore, 1893 belongs to Ypthimina Reuter, 1896. The following taxa are distinct species rather than subspecies (of species shown in parenthesis): Pyrisitia westwoodii (Boisduval, 1836) (not Pyrisitia dina (Poey, 1832)), Biblis aganisa Boisduval, 1836 (not Biblis hyperia (Cramer, 1779)), Phystis variegata (Röber, 1913) and Phystis pratti (A. Hall, 1935) (not Phystis simois (Hewitson, 1864)), Phocides batabano (Lucas, 1857) and Phocides bicolora (Boddaert, 1783) (not Phocides pigmalion (Cramer, 1779)), Lobotractus mysie (Dyar, 1904) (not Lobotractus valeriana (Plötz, 1881)). Nahida coenoides (Hewitson, 1870) is conspecific with Ithomeis aurantiaca H. Bates, 1862. Additional new and revised combinations are: Teriocolias deva (E. Doubleday, 1847), Teriocolias reticulata (A. Butler, 1871), Hesperocharis leucothea (Molina, 1782), Methone euploea (Hewitson, [1855]), Methone eucerus (Hewitson, 1872), Methone hypophaea (Godman & Salvin, 1878), Methone eubule (R. Felder, 1869), Methone onorata (Hewitson, 1869), Methone authe (Godman, 1903), Methone dolichos (Staudinger, [1887]), Methone baucis (Stichel, 1919), Methone eucrates (Hewitson, 1872), Napaea danforthi A. Warren & Opler, 1999, Napaea dramba (J. Hall, Robbins & Harvey, 2004), Napaea sanarita (Schaus, 1902), Napaea agroeca Stichel, 1910, Napaea tumbesia J. Hall & Lamas, 2001, Napaea umbra (Boisduval, 1870), Napaea phryxe (C. & R. Felder, 1865), Napaea cebrenia (Hewitson, [1873]), Napaea loxicha (R.G. Maza & J. Maza, 2016), Napaea maya (J. Maza & Lamas, 2016), Napaea necaxa (R.G. Maza & J. Maza, 2018), Napaea totonaca (R.G. Maza & J. Maza, 2016), Mesene aeolia (Bates, 1868), Pterographium hypochloris (Bates, 1868), Phaenochitonia florus (Fabricius, 1793), Ourocnemis carausius (Westwood, 1851), Ourocnemis principalis (Hopffer, 1874), Ourocnemis renaldus (Stoll, 1790), and Ourocnemis aerosus (Stichel, 1924), Hallonympha maculosa (Bates, 1868), Exoplisia aphanis (Stichel, 1910), Phystis fontus (A. Hall, 1928), Phocides batabano okeechobee (Worthington, 1881), and Phocides batabano batabanoides (W. Holland, 1902). Finally, we confirm the combination Zabuella castanea (Prittwitz, 1865) and find Pyrgus centaureae dzekh Gorbunov, 2007 as a new subspecies for North America.

Insect egg-killing: a new front on the evolutionary arms-race between brassicaceous plants and pierid butterflies

Evolutionary arms-races between plants and insect herbivores have long been proposed to generate key innovations such as plant toxins and detoxification mechanisms that can drive diversification of the interacting species. A novel front-line of plant defence is the killing of herbivorous insect eggs. We test whether an egg-killing plant trait has an evolutionary basis in such a plant-insect arms-race. Within the crucifer family (Brassicaceae), some species express a hypersensitive response (HR)-like necrosis underneath butterfly eggs (Pieridae) that leads to eggs desiccating or falling off the plant. We studied the phylogenetic distribution of this trait, its egg-killing effect on and elicitation by butterflies, by screening 31 Brassicales species, and nine Pieridae species. We show a clade-specific induction of strong, egg-killing HR-like necrosis mainly in species of the Brassiceae tribe including Brassica crops and close relatives. The necrosis is strongly elicited by pierid butterflies that are specialists of crucifers. Furthermore, HR-like necrosis is linked to PR1 defence gene expression, accumulation of reactive oxygen species and cell death, eventually leading to egg-killing. Our findings suggest that the plants' egg-killing trait is a new front on the evolutionary arms-race between Brassicaceae and pierid butterflies beyond the well-studied plant toxins that have evolved against their caterpillars.

High resolution DNA barcode library for European butterflies reveals continental patterns of mitochondrial genetic diversity

The study of global biodiversity will greatly benefit from access to comprehensive DNA barcode libraries at continental scale, but such datasets are still very rare. Here, we assemble the first high-resolution reference library for European butterflies that provides 97% taxon coverage (459 species) and 22,306 COI sequences. We estimate that we captured 62% of the total haplotype diversity and show that most species possess a few very common haplotypes and many rare ones. Specimens in the dataset have an average 95.3% probability of being correctly identified. Mitochondrial diversity displayed elevated haplotype richness in southern European refugia, establishing the generality of this key biogeographic pattern for an entire taxonomic group. Fifteen percent of the species are involved in barcode sharing, but two thirds of these cases may reflect the need for further taxonomic research. This dataset provides a unique resource for conservation and for studying evolutionary processes, cryptic species, phylogeography, and ecology.

Wolbachia affects mitochondrial population structure in two systems of closely related Palaearctic blue butterflies

The bacterium Wolbachia infects many insect species and spreads by diverse vertical and horizontal means. As co-inherited organisms, these bacteria often cause problems in mitochondrial phylogeny inference. The phylogenetic relationships of many closely related Palaearctic blue butterflies (Lepidoptera: Lycaenidae: Polyommatinae) are ambiguous. We considered the patterns of Wolbachia infection and mitochondrial diversity in two systems: Aricia agestis/Aricia artaxerxes and the Pseudophilotes baton species complex. We sampled butterflies across their distribution ranges and sequenced one butterfly mitochondrial gene and two Wolbachia genes. Both butterfly systems had uninfected and infected populations, and harboured several Wolbachia strains. Wolbachia was highly prevalent in A. artaxerxes and the host's mitochondrial structure was shallow, in contrast to A. agestis. Similar bacterial alleles infected both Aricia species from nearby sites, pointing to a possible horizontal transfer. Mitochondrial history of the P. baton species complex mirrored its Wolbachia infection and not the taxonomical division. Pseudophilotes baton and P. vicrama formed a hybrid zone in Europe. Wolbachia could obscure mitochondrial history, but knowledge on the infection helps us to understand the observed patterns. Testing for Wolbachia should be routine in mitochondrial DNA studies.

Two ways to be endemic. Alps and Apennines are different functional refugia during climatic cycles

Endemics co-occur because they evolved in situ and persist regionally or because they evolved ex situ and later dispersed to shared habitats, generating evolutionary or ecological endemicity centres, respectively. We investigate whether different endemicity centres can intertwine in the region ranging from Alps to Sicily, by studying their butterfly fauna. We gathered an extensive occurrence data set for butterflies of the study area (27,123 records, 269 species, in cells of 0.5 × 0.5 degrees of latitude-longitude). We applied molecular-based delimitation methods (GMYC model) to 26,557 cytochrome c oxidase subunit 1 (COI) sequences of Western Palearctic butterflies. We identified entities based on molecular delimitations and/or the checklist of European butterflies and objectively attributed occurrences to their most probable entity. We obtained a zoogeographic regionalisation based on the 69 endemics of the area. Using phylogenetic ANOVA we tested if endemics from different centres differ from each other and from nonendemics for key ecological traits and divergence time. Endemicity showed high incidence in the Alps and Southern Italy. The regionalisation separated the Alps from the Italian Peninsula and Sicily. The endemics of different centres showed a high turnover and differed in phylogenetic distances, phenology and distribution traits. Endemics are on average younger than nonendemics and the Peninsula-Sicily endemics also have lower variance in divergence than those from the Alps. The observed variation identifies Alpine endemics as paleoendemics, now occupying an ecological centre, and the Peninsula-Sicily ones as neoendemics, that diverged in the region since the Pleistocene. The results challenge the common view of the Alpine-Apennine area as a single "Italian refugium".

Phylogenetic position and taxonomic rearrangement of Davidina (Lepidoptera: Nymphalidae), an enigmatic butterfly genus new for Europe and America

Davidina, an enigmatic butterfly genus described from China in the 19th century, has for a long time been considered a member of the family Pieridae due to its pierid-like wing pattern. In the 20th century, it was transferred to Satyridae (now subfamily Satyrinae of Nymphalidae) based on analysis of the structure of genitalia and placed next to the species-rich genus Oeneis (subtribe Satyrina), being separated from the latter by supposed differences in wing venation. We have conducted a phylogenetic and taxonomic study of the subtribe Satyrina using analysis of molecular and morphological characters. We show that the genus Oeneis is not monophyletic, and consists of two genetically diverged and morphologically differentiated groups that are not sister-groups (Oeneis s.s. and Protoeneis). We also demonstrate that Davidina is closely related to Protoeneis, but not to Oeneis s.s. To resolve this newly discovered non-monophyly and morphological heterogeneity, several species should be removed from Oeneis and transferred to the genus Davidina. As a consequence, we synonymize the name ProtoeneisGorbunov, 2001 with DavidinaOberthür, 1879. We conclude that Davidina is not a monotypic Chinese endemic genus, as has been previously supposed, but is composed of nine species that have a broad distribution area across the Holarctic region, extending to Europe and America.

Ancient divergence, a crisis of salt and another of ice shaped the evolution of the west Mediterranean butterfly Euchloe tagis

The Mediterranean region is an extremely complex hotspot where, since the Miocene, extensive geological, habitat and climate changes have taken place, alternating between warm and cold periods. These phenomena have taken a toll on the genetic composition of species, and surviving lineages have often adapted locally and diverged to the point of (complete) speciation. To study these phenomena, in this study we used one of the most enigmatic butterflies, the Portuguese dappled white, Euchloe tagis, a west Mediterranean endemic with fragmented, morphologically differentiated populations whose status have long been disputed. Even its affiliations with other Anthocharidini are largely unresolved. We used mitochondrial and nuclear markers under a phylogenetic and phylogeographical framework to evaluate its placement among relatives and population differentiation, reconstructing its evolutionary history. We found that this species had a Miocene origin ~15 Mya and was nearest to Euchloe s.s. and Elphinstonia. Its populations showed high genetic diversity but all coalesced to 5.3 Mya, when European and all but one African population diverged. Our multiple findings concerning the evolution of E. tagis through a changing, narrow habitable area might provide a more general perspective on how species survive within this hotspot of paramount importance.

Butterfly dichromatism primarily evolved via Darwin's, not Wallace's, model

Sexual dimorphism is typically thought to result from sexual selection for elaborated male traits, as proposed by Darwin. However, natural selection could reduce expression of elaborated traits in females, as proposed by Wallace. Darwin and Wallace debated the origins of dichromatism in birds and butterflies, and although evidence in birds is roughly equal, if not in favor of Wallace's model, butterflies lack a similar scale of study. Here, we present a large‐scale comparative phylogenetic analysis of the evolution of butterfly coloration, using all European non‐hesperiid butterfly species (n = 369). We modeled evolutionary changes in coloration for each species and sex along their phylogeny, thereby estimating the rate and direction of evolution in three‐dimensional color space using a novel implementation of phylogenetic ridge regression. We show that male coloration evolved faster than female coloration, especially in strongly dichromatic clades, with male contribution to changes in dichromatism roughly twice that of females. These patterns are consistent with a classic Darwinian model of dichromatism via sexual selection on male coloration, suggesting this model was the dominant driver of dichromatism in European butterflies.

A new comprehensive trait database of European and Maghreb butterflies, Papilionoidea

Trait-based analyses explaining the different responses of species and communities to environmental changes are increasing in frequency. European butterflies are an indicator group that responds rapidly to environmental changes with extensive citizen science contributions to documenting changes of abundance and distribution. Species traits have been used to explain long- and short-term responses to climate, land-use and vegetation changes. Studies are often characterised by limited trait sets being used, with risks that the relative roles of different traits are not fully explored. Butterfly trait information is dispersed amongst various sources and descriptions sometimes differ between sources. We have therefore drawn together multiple information sets to provide a comprehensive trait database covering 542 taxa and 25 traits described by 217 variables and sub-states of the butterflies of Europe and Maghreb (northwest Africa) which should serve for improved trait-based ecological, conservation-related, phylogeographic and evolutionary studies of this group of insects. We provide this data in two forms; the basic data and as processed continuous and multinomial data, to enhance its potential usage.

Measurement(s)	resources • Egg Laying • larval environment • pupal environment • geographic location • behavior • size • voltinism • phenology • host plant
Technology Type(s)	digital curation
Factor Type(s)	species
Sample Characteristic - Organism	Papilionoidea
Sample Characteristic - Location	Europe • Northwest Africa

Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12998828

Ecology and Genetic Structure of the Parasitoid Phobocampe confusa (Hymenoptera: Ichneumonidae) in Relation to Its Hosts, Aglais Species (Lepidoptera: Nymphalidae)

The biology of parasitoids in natural ecosystems remains very poorly studied, though they are key species for their functioning. Here we focused on Phobocampe confusa, a Nymphalini specialist, responsible for high mortality rates in charismatic butterfly species in Europe (genus Aglais). We studied its ecology and genetic structure in connection with those of its host butterflies in Sweden. To this aim, we gathered data from 428 P. confusa individuals reared from 6094 butterfly larvae (of A. urticae, A. io, and in two occasions of Araschnia levana) collected over two years (2017 and 2018) and across 19 sites distributed along a 500 km latitudinal gradient. We found that P. confusa is widely distributed along the latitudinal gradient. Its distribution seems constrained over time by the phenology of its hosts. The large variation in climatic conditions between sampling years explains the decrease in phenological overlap between P. confusa and its hosts in 2018 and the 33.5% decrease in the number of butterfly larvae infected. At least in this study, P. confusa seems to favour A. urticae as host. While it parasitized nests of A. urticae and A. io equally, the proportion of larvae parasitized is significantly higher for A. urticae. At the landscape scale, P. confusa is almost exclusively found in vegetated open land and near deciduous forests, whereas artificial habitats are negatively correlated with the likelihood of a nest to be parasitized. The genetic analyses on 89 adult P. confusa and 87 adult A. urticae using CO1 and AFLP markers reveal a low genetic diversity in P. confusa and a lack of genetic structure in both species, at the scale of our sampling. Further genetic studies using high-resolution genomics tools will be required to better understand the population genetic structure of P. confusa, its biotic interactions with its hosts, and ultimately the stability and the functioning of natural ecosystems.