Melanargia Galathea Research Articles

Distinct spatial patterns of genetic structure and diversity in the butterfly Marbled White (Melanargia galathea) inhabiting fragmented grasslands

We adopted a landscape-scale approach to analyze the genetic patterns (diversity, structure, and differentiation) of the Marbled White (Melanargia galathea). This butterfly species is characteristic of semi-dry grasslands, which have substantially declined in Switzerland during past decades. We sampled individuals on a regular grid of the established Biodiversity Monitoring program of Switzerland over five consecutive years, obtaining 1639 genotyped individuals from 185 locations. Results showed that M. galathea populations cluster into five spatially aggregated clusters that largely coincide with the biogeographic regions of Switzerland. Genetic diversity (allelic richness) was higher in the South of the Alps, likely related to immigration dynamics that suggest recolonisation from the South after the last glaciation. Demographic history resulted in distinct isolation by distance (IBD) and by cumulative elevational difference (isolation by altitude, IBA) at large scale, while regional IBD and IBA were less pronounced. This pattern was likely induced by the barrier effect of the high mountains of the Alps impeding continuous northward migration after the last glacial maximum. A temporal analysis revealed that regional genetic diversity did not change strongly during the five sampling years. This result indicates that the genetic diversity pattern in M. galathea has not been noticeably affected by historical land-use change or that the sampling period of five years is too short to detect any changes. Our findings highlight the regionally, topography-induced distinct genetic clusters, relevant for consideration as conservation units and likely reflecting genetic structures similar to those found in other butterfly species of conservation concern.

Exploring Cold Hardiness within a Butterfly Clade: Supercooling Ability and Polyol Profiles in European Satyrinae.

Simple SummaryIn insects distributed in temperate and cold zones, cold hardiness during overwintering crucially affects the distribution, including range shifts due to climate change. Our previous work on the genus Erebia, a cold-adapted and species-rich group of the sub-family Satyrinae (Nymphalidae), disclosed unexpected diversity of cold hardiness strategies, with closely related species surviving or not surviving freezing of larval body fluids. Asking whether this diversity is peculiar to this genus, or may be common in the Satyrinae clade, we investigated supercooling ability, contents of sugars and polyols in overwintering larvae tissues, and evolutionary signal of these traits of eight European Satyrinae species (from seven genera) and compared them with the Erebia representatives investigated earlier. We show that cold hardiness strategies are indeed diverse in the group and that high mountain and continental steppe species employ similar cryoprotection mechanisms, differing from those employed by species of more mesic environments. The cold hardiness of overwintering stages affects the distribution of temperate and cold-zone insects. Studies on Erebia, a species-rich cold-zone butterfly genus, detected unexpected diversity of cold hardiness traits. We expanded our investigation to eight Satyrinae species of seven genera. We assessed Autumn and Winter supercooling points (SCPs) and concentrations of putatively cryoprotective sugars and polyols via gas chromatography–mass spectrometry. Aphantopus hyperantus and Hipparchia semele survived freezing of body fluids; Coenonympha arcania, C. gardetta, and Melanargia galathea died prior to freezing; Maniola jurtina, Chazara briseis, and Minois dryas displayed a mixed response. SCP varied from −22 to −9 °C among species. Total sugar and polyol concentrations (TSPC) varied sixfold (2 to 12 μg × mg−1) and eightfold including the Erebia spp. results. SCP and TSPC did not correlate. Alpine Erebia spp. contained high trehalose, threitol, and erythritol; C. briseis and C. gardetta contained high ribitol and trehalose; lowland species contained high saccharose, maltose, fructose, and sorbitol. SCP, TSPC, and glycerol concentrations were affected by phylogeny. Species of mountains or steppes tend to be freeze-avoidant, overwinter as young larvae, and contain high concentrations of trehalose, while those of mesic environments tend to be freeze-tolerant, overwinter as later instars, and rely on compounds such as maltose, saccharose, and fructose.

The genome sequence of the marbled white butterfly, Melanargia galathea (Linnaeus, 1758).

We present a genome assembly from an individual female Melanargia galathea (the marbled white; Arthropoda; Insecta; Lepidoptera; Nymphalidae). The genome sequence is 606 megabases in span. The majority (99.97%) of the assembly is scaffolded into 25 chromosomal pseudomolecules, with the W and Z sex chromosomes assembled.

Butterflies in corridors: quality matters for specialists

Abstract Agricultural intensification and subsequent landscape homogenisation have caused severe losses of insects across major parts of Europe. In consequence, most animal and plant populations today exist in small and isolated habitat patches. Thus, there is an urgent need to increase landscape permeability to foster the exchange of individuals and thereby to promote the long‐term persistence of populations and species. Corridors can help to connect local habitats and populations. Nonetheless, whether species use a corridor and how species behave in a corridor strongly depend on species' ecology and the quality of the corridor. In this study, we analysed the behaviour of 753 individuals of five butterfly species of the subfamily Satyrinae (Coenonympha pamphilus, C. arcania, Maniola jurtina, Melanargia galathea, and Erebia medusa) in a high‐quality habitat, in two corridors with different habitat qualities, and in arable fields. Butterflies undertake more frequent and much longer flights in arable fields, and a more range‐restricted behaviour with perching and visiting of flowers in corridors and inside the original high‐quality habitat. Specialist butterflies only rarely leave the corridor and fly into the matrix if compared with generalist butterfly species. Furthermore, the relative difference in the probability of leaving a corridor was much more pronounced between the two corridor qualities for specialists than for generalists. In conclusion, corridors with high habitat quality, such as many flowering plants, support species and population persistence. Specialist species especially respond to corridor quality, such as the availability of flowers or a calcareous grassland‐like species composition.

Meleager’s Blue (Meleageria daphnis), Marbled White (Melanargia galathea) and Clouded Yellow (Colias croceus), new and rare species in Lithuania

AbstractA new species for the country’s fauna, two individuals of Meleager’s Blue (Polyommatus daphnis) were discovered in southern Lithuania in 2016. This paper details these occurrences and also presents data on two vagrant species also found in southern Lithuania, specifically Marbled White (Melanargia galathea) and Clouded Yellow (Colias croceus).

Differentiation in the marbled white butterfly species complex driven by multiple evolutionary forces

AbstractAimGenetic and phenotypic data may show convergent or contrasting spatial patterns. Discrepancies between markers may develop in response to different evolutionary forces. In this study we analyse inter‐ and intraspecific differentiation of closely related taxa in the marbled white butterfly species group. Based on genetic and phenotypic characters we test for potential evolutionary drivers and propose a taxonomic revision.LocationWestern Palaearctic (including north‐western Africa).MethodsWe compared distributions of mitochondrial cytochrome c oxidase subunit I gene (COI) sequences, of several allozyme loci, and of the shape of wings and genitalia obtained by applying landmark‐based techniques for the three butterfly species Melanargia galathea (central and eastern Europe), M. lachesis (Iberia) and M. lucasi (North Africa).ResultsAll studied markers showed a strong spatial structure, although discordance among their patterns was detected. COI sequences, wing shape and genitalia indicated a main split between M. galathea and M. lucasi. A lower differentiation between M. galathea and M. lachesis was found in wing shape and reflected in two mutations of the COI gene, while allozymes indicated a strong divergence. Within M. galathea, allozyme data and COI, but not morphology, revealed the existence of a slightly differentiated lineage in the Italian Peninsula, France and Switzerland. Based on COI, Melanargia lucasi was split into two subgroups, a western and an eastern Maghreb lineage.Main conclusionsLong‐term isolation of Melanargia populations between North Africa and Europe led to divergence between M. galathea and M. lucasi. This was followed by a recent differentiation among populations isolated during the cold periods of the Pleistocene, such as M. lachesis in Iberia. These lineages are characterized by a tendency not to overlap in secondary sympatry. The different patterns of the four markers may arise from divergent evolutionary processes and pressures: wings may be mainly affected by natural selection, genital structures by sexual selection, whereas long‐term isolation and drift may have driven divergence of mitochondrial DNA and allozymes.

The ecology and conservation of butterflies and moths

In 2011, we published the proceedings of Butterfly Conservation’s Sixth International Symposium ‘2010 and beyond for Lepidoptera’ (volume 15:1–365). That meeting attempted to assess whether the Convention on Biological Diversity’s aspiration to significantly reduce the rate of biodiversity loss in the Lepidoptera had been achieved. Sadly the conclusion was that it had not. Nevertheless, the papers in that Special Edition were not uniformly concerned with doom and gloom and many reported important insights into species’ ecology and approaches which could lead to improvements in the future. Now, 4 years on, we publish the written contributions to the Seventh Symposium held in April 2014. The Symposium title was deliberately less focussed than that held in 2010 to attempt to capture a broad snapshot of work on Lepidoptera from around the world—in that it was successful, with over 80 presentations from 28 countries. The Journal is proud to present 20 written papers from that intense and exhilarating 3-day long meeting. Nineteen papers are presented in this edition, one has already been published (Maes et al. 2014). Inevitably the preoccupation of many authors was with the ongoing impacts of climate change and how to overcome them. Parmesan et al. (2015) examined elevational range and hostplant shifts in the quino checkerspot Euphydryas editha quino whilst Wilson et al. (2015) examined turnover, habitat quality and microclimate changes at a contracting range margin of the Apollo Parnassius apollo in the Sierra de Guadarrama mountains of Spain. Indeed, microclimate was something of a theme: Curtis and Isaac (2015) examined the impact of microclimate heterogeneity on the Glanville fritillary Melitaea cinxia, Hindle et al. (2015) scrutinised the value of topographical variation to the marbled white butterfly Melanargia galathea, whilst Suggitt et al. (2015) studied the influence of microclimate in buffering the effects of climate change and contributing to landscape-scale persistence of butterflies and moths. Dispersal studies were also evident ranging from an investigation of threats to the scarce copper (Lycaena virgaureae) from development in Sweden (Haaland 2015) and the impact of altitude (Cassacci et al. 2015). Several papers were concerned with population trends (Swengel and Swengel 2015a, b; Curtis et al. 2015) including monitoring approaches (Roy et al. 2015) or conservation at very different spatial scales such as South Africa (Edge and Mecenero 2015) and the vineyards of Washington State in the USA (James et al. 2015). Autecological studies are always welcome; Edge and Bazin (2015) contributed an indepth study of the Knysna skolly Thestor brachycerus brachycerus, Celik et al. (2015) a paper on the habitat quality determinants for the false ringlet Coenonympha Oedipus, whilst Tjornlov et al. (2015) focussed on & John W. Dover J.W.Dover@staffs.ac.uk

Topographical variation reduces phenological mismatch between a butterfly and its nectar source

The timing of many biological events, including butterfly imago emergence, has advanced under climate change, with the rate of these phenological changes often differing among taxonomic groups. Such inter-taxa variability can lead to phenological mismatches. For example, the timing of a butterfly’s flight period may become misaligned with a key nectar resource, potentially increasing the extinction risk to both species. Here we fit statistical models to field data to determine how the phenology of the marbled white butterfly, Melanargia galathea, and its main nectar source, greater knapweed, Centaurea scabiosa, have changed over recent years at three sites across the UK. We also consider whether topographical diversity affects C. scabiosa’s flowering period. At our focal site, on the species’ northern range limit, we find that over a 13-year period the onset of C. scabiosa’s flowering period has become later whilst there is no obvious trend over time in the onset of M. galathea’s flight period. In recent years, butterflies have started to emerge before their key nectar source was available across most of the site. This raises the intriguing possibility that phenological mismatch could be an unrecognised determinant of range limits for some species. However, the presence of topographical diversity within the site decreased the chance of a mismatch occurring by increasing the length of the flowering period by up to 14 days. We suggest that topographical diversity could be an important component in minimising phenological mismatches under future climate change.

The role of the North Atlantic Oscillation in controlling U.K. butterfly population size and phenology

1. The North Atlantic Oscillation (NAO) exerts considerable control on U.K. weather. This study investigates the impact of the NAO on butterfly abundance and phenology using 34 years of data from the U.K. Butterfly Monitoring Scheme (UKBMS).2. The study uses a multi-species indicator to show that the NAO does not affect overall U.K. butterfly population size. However, the abundance of bivoltine butterfly species, which have longer flight seasons, were found to be more likely to respond positively to the NAO compared with univoltine species, which show little or a negative response.3. A positive winter NAO index is associated with warmer weather and earlier flight dates for Anthocharis cardamines (Lepidoptera: Pieridae), Melanargia galathea (Lepidoptera: Nymphalidae), Aphantopus hyperantus (Lepidoptera: Nymphalidae), Pyronia tithonus (Lepidoptera: Nymphalidae), Lasiommata megera (Lepidoptera: Nymphalidae) and Polyommatus icarus (Lepidoptera: Lycaenidae). In bivoltine species, the NAO affects the phenology of the first generation, the timing of which indirectly controls the timing of the second generation.4. The NAO influences the timing of U.K. butterfly flight seasons more strongly than it influences population size.

From Africa to Europe and back: refugia and range shifts cause high genetic differentiation in the Marbled White butterfly Melanargia galathea

BackgroundThe glacial-interglacial oscillations caused severe range modifications of biota. Thermophilic species became extinct in the North and survived in southern retreats, e.g. the Mediterranean Basin. These repeated extinction and (re)colonisation events led to long-term isolation and intermixing of populations and thus resulted in strong genetic imprints in many European species therefore being composed of several genetic lineages. To better understand these cycles of repeated expansion and retraction, we selected the Marbled White butterfly Melanargia galathea. Fourty-one populations scattered over Europe and the Maghreb and one population of the sibling taxon M. lachesis were analysed using allozyme electrophoresis.ResultsWe obtained seven distinct lineages applying neighbour joining and STRUCTURE analyses: (i) Morocco, (ii) Tunisia, (iii) Sicily, (iv) Italy and southern France, (v) eastern Balkans extending to Central Europe, (vi) western Balkans with western Carpathian Basin as well as (vii) south-western Alps. The hierarchy of these splits is well matching the chronology of glacial and interglacial cycles since the Günz ice age starting with an initial split between the galathea group in North Africa and the lachesis group in Iberia. These genetic structures were compared with past distribution patterns during the last glacial stage calculated with distribution models.ConclusionsBoth methods suggest climatically suitable areas in the Maghreb and the southern European peninsulas with distinct refugia during the last glacial period and underpin strong range expansions to the North during the Postglacial. However, the allozyme patterns reveal biogeographical structures not detected by distribution modelling as two distinct refugia in the Maghreb, two or more distinct refugia at the Balkans and a close link between the eastern Maghreb and Sicily. Furthermore, the genetically highly diverse western Maghreb might have acted as source or speciation centre of this taxon, while the eastern, genetically impoverished Maghreb population might result from a relatively recent recolonisation from Europe via Sicily.

Patch occupancy, number of individuals and population density of the Marbled White in a changing agricultural landscape

Metapopulation theory predicts the occurrence of animals in habitat patches. In this paper, we tested predictions based on this theory, including effects of spatial autocorrelation, to describe factors affecting the presence, local number of individuals and density of the Marbled White butterfly Melanargia galathea in habitat patches spread across the agricultural landscape of southern Poland. This agricultural landscape has undergone significant changes in recent decades due to the country’s political transformation and is currently characterized by a large proportion of fallow (abandoned) land. We compared 48 occupied habitat patches with 60 unoccupied ones. Positive spatial autocorrelation was found in the number and density of individuals in habitat patches. The probability of patch occupancy was higher for patches that were larger, had a higher proportion of edges, were located closer to the nearest neighbouring local population and to the nearest piece of fallow, contained a smaller area of cut grass, and also had more nectar resources. The number of Marbled Whites in habitat patches was positively related to the patch area, the distance to the nearest fallow and the abundance of nectar resources, but was negatively related to the density of shrubs. The density of individuals was positively related to abundance of flowers, proportion of edge in a patch and distance to the nearest fallow, but it was negatively related to patch area, vegetation height and grass cover. These results indicate that recent land-use changes in agricultural landscapes have had both positive and negative effects on the presence and local number of individuals and density of the Marbled White. These changes affect the metapopulation of the species through changes in habitat quality and landscape connectivity in the area surrounding habitat patches.

High dispersal ability and low genetic differentiation in the widespread butterfly species Melanargia galathea

Agricultural intensification caused a fragmentation of flower-rich extensively used meadows which resulted in the reduction of the abundance of species of these habitats. The abundance pattern and the dispersal behaviour of species influence the connectivity of local populations. In this context exchange rates can be directly measured by mark release recapture (MRR) studies and indirectly by genetic analysis. Both approaches are used in our study in a comparative way. As a test species to investigate the influence of habitat interconnectivity on a local and regional scale, we selected the butterfly Melanargia galathea (Lepidoptera, Nymphalidae), a widely distributed species, which is common on flower-rich meadows in our study area in western Germany. We marked 3,175 individuals of four neighbouring sites in a mark-release-recapture study and analysed 18 allozyme loci for 644 individuals sampled over 17 sites. Only 3.3% of the total genetic variance was found among samples, thus supporting the detected between-patch movements. Both approaches revealed a high exchange rate among local populations. Moderate between- and high within-patch movements were recorded by MRR analysis, dependent on the geographical distance. The two analytical tools showed high estimated effective population sizes for all populations. In the light of conservation biology, the combination of the MRR and allozyme data support the assumption that high dispersal ability and habitat interconnectivity countervail genetic differentiation and enable the maintenance of a high level of genetic differentiation.

The genetic consequence of differing ecological demands of a generalist and a specialist butterfly species

Many studies aim at testing the impact of recent fragmentation on the genetic diversity and connectivity of populations, while some species do exist naturally in frag- mented landscapes because of their habitat requirements. Therefore, it is important to look at the genetic signatures of species occurring in naturally fragmented landscapes in order to disentangle the effect of fragmentation from the effect of habitat requirements. We selected two Nymphalid butterflies for this purpose. While Melanargia galathea is a common butterfly in flower-rich meadows, Melitaea aurelia is closely connected to calcareous grasslands, thus being historically fragmented due to its ecological demands. For the analysis of the genetic response on these opposed patterns, we analysed 18 allozyme loci for 789 individuals (399 individuals of M. galathea and 390 individuals of M. aurelia )i n a western German study region with adjacent areas in Luxemburg and northeastern France. Both species showed similarly low genetic differentiations among local populations (M. galathea: FST 3.3%; M. aurelia: FST 3.6%), both combined with a moderate level of inbreeding. Isolation-by-distance analysis revealed a significant correlation for both spe- cies with similar amounts of explained variances (M. galathea: r 2 = 27.8%; M. aurelia: r 2 = 28.5%). Most parameters of genetic diversity were higher in M. galathea than in M. aurelia, but the latter species had a considerably higher amount of rare or locally restricted genes; the differing ecological demands are thus reflected in these differences. Both species thus seem to be genetically well suited to their respective ecological requirements. In the light of conservation genetics, we deduce that highly fragmented populations are not necessarily prone to extinction. The extinction risk might be linked to the life history of an organism and its population genetic structure.

Assisted colonization in a changing climate: a test‐study using two U.K. butterflies

AbstractRecent climatic change in temperate regions has been rapid and there is mounting speculation that species are failing to keep track of suitable climate, perhaps necessitating assisted colonization for some species. An inability to spread into new areas may result in large reductions in species’ ranges in the future, and threaten the survival of some species. Here we use “species‐climate” models to predict suitable sites for introductions beyond current range margins, using two U.K. butterfly species. We introducedMelanargia galathea(marbled white) andThymelicus sylvestris(small skipper) into two sites in northern England, ∼65 and ∼35 km beyond their then‐range margins, respectively, to sites that were predicted to be climatically suitable and that appeared to contain suitable habitat for the species. Both introduced populations grew and expanded their range over 6 years (2001–2006; still thriving in 2008), suggesting the existence of a colonization lag and providing evidence that well‐planned assisted colonization can be successful. We suggest that assisted colonization may be a feasible and cost‐effective means of enabling certain species to track climatic change.

SELECTION TOWARD SHORTER FLOWERS BY BUTTERFLIES WHOSE PROBOSCES ARE SHORTER THAN FLORAL TUBES

Darwin's meticulous observations on the function of floral shape led to his famous prediction of a long-tongued pollinator, which he believed to be the evolutionary trigger for the long-spurred flowers of the Madagascar star orchid. Although tubular flowers are common, long tubes or spurs are an exception, suggesting that selection maintaining short flowers is widespread. Using the butterfly-pollinated carnation Dianthus carthusianorum and two butterfly species differing in proboscis length (Melanargia galathea and Inachis io) as model organisms, we experimentally demonstrate a reduction in pollinator efficiency with an increasing difference between proboscis length and floral tube length. Such a relationship is a prerequisite for the evolution of floral shape in response to pollinator morphology.

Africa goes Europe: The complete phylogeography of the marbled white butterfly species complex Melanargia galathea/ M. lachesis (Lepidoptera: Satyridae)

Climatic oscillations influence the distribution of species in time. Thermophilic species survived the ice ages in refugia around the Mediterranean. Northern Africa is one of the possibly important refugia. In this study we test the genetic differentiation between northern African and European populations, using the marbled white butterfly species complex, Melanargia galathea/ M. lachesis, as a model. We studied 18 allozyme loci in 876 individuals from 23 populations representing a major part of Europe (northern Spain to Romania) and the western part of northern Africa (Atlas Mountains). The African populations resemble the European ones in allelic richness; their genetic diversity is higher than in Europe. Cluster analysis discriminated five European genetic groups: M. lachesis, a western European lineage, and three eastern European lineages. However, the African samples did not form a separate cluster within this phenogram, but clustered randomly within the Balkan/southeastern European groups. The genetic differentiation among the African populations ( F ST 8.8%) was higher than that within any of the European lineages ( F ST 2.6–5.5%). The high genetic diversity and the relatively strong differentiation of the four African populations sampled in a comparatively limited area of the Atlas Mountains indicate that the most probable origin of M. galathea is northern Africa, with its sibling species, M. lachesis, evolving in parallel in Iberia. Most probably, M. galathea colonised Europe first during the Eem interglacial, some 130 ky ago. Since M. lachesis must have existed on the Iberian peninsula during that period already, M. galathea should have reached Europe via Italy. The genetic differentiation to distinct groups in Europe most probably evolved during the following Würm glacial period.

Genetic differentiation of the marbled white butterfly, Melanargia galathea, accounts for glacial distribution patterns and postglacial range expansion in southeastern Europe

Isolation of Mediterranean species in the southern European peninsulas during the cold glacial phases often resulted in differentiation of several genetic lineages confined to the respective peninsulas. However, whilst there is good genetic evidence for multiple refugia in Iberia, there are only limited data available for the Balkans. Therefore, we wish to examine the hypothesis of a strong genetic structuring within southeastern Europe for the existence of multiple Balkan differentiation centres and/or several leading edges. As a model we use the marbled white butterfly, Melanargia galathea. We studied 18 allozyme loci of 564 individuals from 16 populations distributed over a large part of southeastern Europe. The single populations showed moderately high genetic diversity and no northward decline of genetic diversity was detected. The overall genetic differentiation between populations was considerable (F(ST) 7.0%). Cluster analysis discriminated three genetic groups: (i) a western flank in the former Yugoslavia, parts of eastern Austria and Hungary; (ii) an eastern flank with populations from Bulgaria and Romania (south of the southern Carpathians and eastern Carpathians); and (iii) the eastern Carpathian Basin. Hierarchical variance analysis distributed 53% of the variance among populations between these three groups. One sample from the Greek-Bulgarian border clustered within the eastern flank, but showed some tendency towards the eastern Carpathian Basin populations. Two populations from Carinthia clustered together with the eastern Carpathian Basin ones and a population from Styria showed an intermediate genetic composition between the three groups. Most probably, the eastern and the western flank groups are due to postglacial range expansion from the northeastern and the northwestern edges of the glacial differentiation centre (so-called leading edges). The eastern Carpathian Basin group may have resulted from postglacial expansion from northern Greece through valley systems of the central Balkan peninsula, maybe even expanding westwards north of the Balkan mountains reaching some parts of eastern Austria (e.g. Carinthia). Therefore, the Balkanic refugium of M. galathea may or may not have been continuous along the coastal areas of the Mediterranean, but must have been strongly genetically structured.

The fourth paradigm pattern of post‐glacial range expansion of European terrestrial species: the phylogeography of the Marbled White butterfly (Satyrinae, Lepidoptera)

AbstractAim Three paradigm patterns of post‐glacial dispersal are known for terrestrial species in Europe. However, the possibility of a fourth arises with the Italian and the Balkan lineages expanding to central Europe and the Iberian one being trapped by the Pyrenees. We test this hypothesis by analysing the molecular biogeography of the Marbled White butterfly.Location Twelve populations distributed over a major part of the European range of Melanargia galathea and M. lachesis.Methods We studied 18 allozyme loci of 403 individuals from 12 populations. Butterflies were sampled in the field, frozen in liquid nitrogen and stored under these conditions until analysis. We used cellulose acetate plates for allozyme electrophoresis.Results We detected three major genetic lineages within the M. galathea/lachesis complex. The M. lachesis sample from the southern Pyrenees was strongly genetically differentiated from M. galathea (FCT: 0.312). Melanargia galathea splits into two major genetic lineages (FCT: 0.115), which both were found in post‐glacially invaded regions. The further differentiation within these lineages was comparably low (FSC: 0.028). The genetic diversity within populations was high compared with other butterfly species.Main conclusions Our findings support the existence of a fourth pattern with only the Iberian lineage not contributing considerably to the post‐glacial colonization of central Europe. Preliminary studies in other butterfly species of dry grasslands support the importance of this pattern possibly representing a fourth paradigm. The high genetic diversity within populations might be one reason for the recently observed expansions at the northern distribution limits.

Dispersal, landscape occupancy and population structure in the butterfly Melanargia galathea

Dispersal is a key ecological process linking metapopulation dynamics in the landscape to distribution patterns at larger spatial scales. In this study, we investigated the landscape occupancy and genetic population structure of a butterfly species, Melanargia galathea. Several landscapes differing in composition and structure were sampled as well as populations at different spatial scales. We found that M. galathea occupied 91.3% of all habitat patches available within a particular landscape, probably due to a dominance of landscape scale processes such as rescue effect and recolonisation. A high level of genetic polymorphism within the sampled populations and a very low amount of genetic differentiation between populations was observed (Gst=0.034), characteristic of species with high dispersal capacity and/or high density. High dispersal rates ensured considerable gene mixing at the landscape scale while the influence of distance on dispersal success was detected at the regional and continental scales by a significant amount of isolation by distance. We also found that, at the landscape scale, the dispersal of this butterfly species was influenced by the spatial distribution of its habitat patches. Die Ausbreitung ist ein ökologischer Schlüsselprozess, der die Metapopulationsdynamik in einer Landschaft mit den Verbreitungsmustern auf einer größeren räumlichen Skala verbindet. In dieser Studie untersuchten wir die Verbreitungsmuster und die genetische Populationsstruktur einer Schmetterlingsart, Melanargia galathea. Es wurden sowohl einige Landschaften beprobt, die sich in der Zusammensetzung und der Struktur unterschieden, als auch Populationen auf verschiedenen räumlichen Skalen. Wir fanden, dass M. galathea 91.3% aller verfügbaren Habitatflecken in einer bestimmten Landschaft besetzte, möglicherweise aufgrund der Dominanz von Landschaftsskalenprozessen wie “Rescue-Effekt” und Rekolonisation. Es wurde ein hoher genetischer Polymorphismuslevel und ein sehr geringer Umfang genetischer Differenzierung innerhalb der beprobten Populationen beobachtet (Gst=0.034), was charakteristisch für Arten mit einer großen Ausbreitungsfähigkeit und/oder hoher Dichte ist. Hohe Ausbreitungsraten sicherten eine beträchtliche Genvermischung auf der Landschaftsskala, während der Einfluss der Entfernung auf den Verbreitungserfolg auf der regionalen und kontinentalen Skala durch einen signifikanten Anteil der Isolation aufgrund von Entfernung festgestellt wurde. Wir fanden auch, dass auf der Landschaftsskala die Ausbreitung dieses Schmetterlings durch die räumliche Verteilung der Habitatflecken beeinflusst wurde.

Parasitism of non-target butterflies by Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae) under field cage and field conditions

Abstract The egg parasitoid Trichogramma brassicae Bezdenko was introduced from Moldavia to western Europe some 30 years ago and since then has been inundatively released to control the European corn borer, Ostrinia nubilalis Hubner, in maize. We investigated parasitism of non-target butterfly eggs by T. brassicae in field cages and under field conditions in Switzerland. Parasitism of eggs (exposed for 24 h) of six non-target species (Papilio machaon L., Clossiana selene Denis and Schiffermuller, Maniola jurtina L., Melanargia galathea L., Hipparchia alcyone Denis and Schiffermuller, Cyaniris semiargus Rottemburg) in field cages of 2×2×2 m ranged between 2.5 and 18.7% when based on a relative high number of released parasitoid females ( 780±273 SD/cage ). This number is 16-fold more compared to agricultural practices (120,000/ha). As a control, Ephestia kuehniella Zeller eggs were glued on the same plant. A difference in parasitism rates between the non-target species and E. kuehniella was only observed for M. galathea. During inundative releases of T. brassicae in maize, sentinel eggs of two suitable non-target hosts and of E. kuehniella were exposed for 72 h. Parasitism rates of E. kuehniella egg masses inside maize fields averaged 40% compared to significantly lower parasitism rates of 26.2 and 12.6% for eggs of H. alcyone and M. galathea. At 2 m distance from the maize field, parasitism rates decreased to 2.3% for M. galathea, 6.1% for H. alcyone, and 9.8% for E. kuehniella while no single egg was found parasitized at 20 m distance from the release fields. We conclude that, although the tested non-target butterflies were all attacked under semi-field and field conditions, effects on non-target butterflies due to mass released T. brassicae are minimal.