Why small is beautiful: wing colour is free from thermoregulatory constraint in the small lycaenid butterfly, Polyommatus icarus

We examined the roles of wing melanisation, weight, and basking posture in thermoregulation in Polyommatus Icarus, a phenotypically variable and protandrous member of the diverse Polyommatinae (Lycaenidae). Under controlled experimental conditions, approximating to marginal environmental conditions for activity in the field (= infrequent flight, long duration basking periods), warming rates are maximised with fully open wings and maximum body temperatures are dependent on weight. Variation in wing melanisation within and between sexes has no effect on warming rates; males and females which differ in melanisation had similar warming rates. Posture also affected cooling rates, consistent with cooling being dependent on convective heat loss. We hypothesise that for this small sized butterfly, melanisation has little or no effect on thermoregulation. This may be a factor contributing to the diversity of wing colours in the Polyommatinae. Because of the importance of size for thermoregulation in this small butterfly, requirements for attaining a suitable size to confer thermal stability in adults may also be a factor influencing larval feeding rates, development time and patterns of voltinism. Our findings indicate that commonly accepted views of the importance of melanisation, posture and size to thermoregulation, developed using medium and large sized butterflies, are not necessarily applicable to small sized butterflies

Integrating three comprehensive datasets shows that mitochondrial DNA variation is linked to species traits and paleogeographic events in European butterflies

Understanding the dynamics of biodiversity, including the spatial distribution of genetic diversity, is critical for predicting responses to environmental changes, as well as for effective conservation measures. This task requires tracking changes in biodiversity at large spatial scales and correlating with species functional traits. We provide three comprehensive resources to understand the determinants for mitochondrial DNA differentiation represented by i) 15,609 COI sequences and ii) 14 traits belonging to 307 butterfly species occurring in Western‐Central Europe and iii) the first multi‐locus phylogenetic tree of all European butterfly species. By applying phylogenetic regressions we show that mitochondrial DNA spatial differentiation (as measured with Gst, G'st, D and Dst) is negatively correlated with species traits determining dispersal capability and colonization ability. Thanks to the high spatial resolution of the COI data, we also provide the first zoogeographic regionalization maps based on intraspecific genetic variation. The overall pattern obtained by averaging the spatial differentiation of all Western‐Central European butterflies shows that the paradigm of long‐term glacial isolation followed by rapid pulses of post‐glacial expansion has been a pervasive phenomenon in European butterflies. The results and the extensive datasets we provide here constitute the basis for genetically‐informed conservation plans for a charismatic group in a continent where flying insects are under alarming decline

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

Historical and current patterns of gene flow in the butterfly Pararge aegeria

Aim. We have investigated the phylogeography and genetic structure of the Speckled Wood butterfly (Pararge aegeria) across its entire distribution range and studied its dispersal both on mainland and across sea straits. The apparent lack of gene flow between Sardinia and Corsica was further investigated by means of mating experiments. Location. Europe and North Africa. Methods. We sampled 345 individuals and sequenced one mitochondrial gene (Cytochrome c Oxidase subunit I, COI) for all samples and two nuclear genes (wingless and zerknullt) for a subset of the specimens. A total of 22 females from Corsica and Sardinia were used to establish a series of crosses to investigate reproductive compatibility and were screened for the presence of Wolbachia. Bayesian inference (BI) and haplotype networks were employed to infer phylogenetic relationships and a Principal Coordinate Analysis (PCoA) was used to represent 4 geographical patterns of genetic diversity. Mating and courtship data were analysed using linear mixed effect models. Results. We detected two main COI lineages separated by the Mediterranean Sea and maintained over relatively short sea straits. While nuclear gene variation was generally in agreement with that of COI, this was not the case in all areas (e.g. Iberian Peninsula and Corsica/Sardinia). Mating experiments revealed no evidence of reproductive isolation between the lineages, nor clear relation to Wolbachia infection status. Main conclusions. We propose that following the post-glacial recolonisation of Europe, the ancestral COI lineage of P. aegeria was maintained in North Africa and Mediterranean islands, while a new lineage colonised from Eastern Europe, replacing and apparently outcompeting the ancestral variant. Several hypotheses are discussed that may explain the local discordance between the nuclear genes and COI, including sex-specific dispersal, selection and differential rates of gene evolution

Rise and fall of island butterfly diversity : understanding genetic differentiation and extinction in a highly diverse archipelago

Aim. We describe fine-scale diversity patterns of the entire butterfly fauna occurring on the Tuscan Archipelago. By assessing the traits associated with population diversification, haplotype uniqueness and extinction, we aim to identify the factors determining the origin and maintenance of genetic diversity, and population vulnerability to environmental changes. Location. Tuscan Archipelago, Sardinia, Tuscany (Italy) and Corsica (France). Methods. We built a mtDNA dataset (1,303 COI sequences) for the 52 butterfly species reported in the Archipelago, also including specimens from neighbouring areas, and compiled data on 12 species traits and on the apparent extinction of species from the main islands. We calculated indices that measure genetic differentiation, and using phylogenetic regressions we evaluated the relationships between these indices and species traits. Finally, we inferred which traits are associated with disappearance of species on individual islands using phylogenetic regression. Results. The overall spatial pattern of genetic diversity corresponded with the proximity of the areas, but strong contrasts were also identified between geographically close areas. Together with the island endemics, several common and widespread species had a high genetic diversification among islands and mainland. Phylogenetic regressions revealed that smaller-sized, more specialized species, with a preference for drier regions, displayed greater genetic structure and/or haplotype uniqueness. Species that disappeared from islands had a higher population diversification. Capraia has experienced a notable loss of diversity, which significantly affected species with shorter flight periods. Main conclusions. Tuscan island butterflies are characterized by strong genetic contrasts and species differ in their contribution to the overall genetic diversity. By ranking the species for their contribution to genetic diversity and identifying the traits linked to the emergence and maintenance of diversity, we have developed a valuable tool for prioritizing populations as targets for monitoring and conservation action. The dataset constructed also represents a valuable resource for testing biogeographical hypotheses

Cross-water transfer by common butterflies (Lepidoptera: Rhopalocera): clear examples of ignoring the highway

Clear examples of ignoring landscape corridors are given for allegedly sedentary butterflies observed in the process of dispersing from habitats; these are discussed in the context of the provision of corridors in managing the British landscape for maintaining populations of Lepidoptera

Functional significance of butterfly wing morphology variation

The relatively large and colourful wings are by far the most apparent feature of adult butterflies. Butterfly wing morphology varies between species, but often also within species. This variation extends to colour, pattern, size, shape, thickness, distribution of mass and venation pattern, and has attracted much attention from evolutionary biologists. Butterfly wings have a range of interacting functions: flight, thermoregulation, intraspecific signalling and communication with predators. Wing size and shape, relative to body mass and thoracic muscle mass, are important determinants of flight dynamics. Changes in these traits may indicate changes in flight power, and probably the ability to sustain flight. This has particularly been studied in a context of habitat fragmentation. Manoeuvrability and the efficiency of flight is, however, also dependent on the way butterflies move their wings. The analysis of in flight biomechanics warrants more detailed attention. Detailed studies of butterfly body temperatures indicate that for many species adult activity becomes optimal within the range 28–38 °C. However, some butterflies fly with lower body temperatures and differences may occur within species. Warming by the adoption of species-specific basking postures to absorb solar radiation is affected by pigment and scale properties of the wings. There can be a complicated interplay between morpholog- ical variation, geographical variation of temperature and weather-dependent microhabitat use, affecting activity. Butterfly wings have communicative functions to predators, but only a few studies have attempted to quantify background matching of butterfly wings. Once detected, the presence of startling devices (e.g. wing tails) alter the chance of consumption. The effectiveness of marginal eyespots on the wings warrants, however, further experimental testing. The quantitative nature of UV coloration extends to many species and to date, predation studies have ignored this component. There is also a UV component to butterfly vision. Hence, it is essential to consider this if we want to understand intraspecific communication and mating behaviour. The functioning of all the elements of wing morphology depends on habitat structure. Many species show geographical or altitudinal variation in wing morphology, and seasonal variation within species with more than one generation a year. With increasing information on wing morphology and flight on individual species it is becoming evident that generalities are becoming harder to make. There is an urgency to understand fully this aspect of butterfly ecology to help understand how increasingly vulnerable species function and persist

Phylogenetic, habitat, and behavioural aspects of possum behaviour in European lepidoptera

Volume: 39Start Page: 80End Page: 8

Phylogenetic, habitat, and behavioural aspects of possum behaviour in European Lepidoptera

We describe the behaviour of playing possum, or thanatosis, in mate rejection by non-receptive female butterflies of the Satyrinae of the Palearactic. In this behaviour females feign death with closed wings and release themselves from the substrate on which they are settled. This behaviour only occurs with extreme male persistence and is the final part of a mate-rejection behavioural sequence. We suggest that this behaviour may be relatively rare, possibly restricted to the tribes Elymiini and Maniolini. There are potential associations with female mating frequency, male mate-locating mechanisms and the physical structure of habitats where attempted mating occurs. We suggest that the behaviour occurs in species where females occasionally mate more than once, where the predominant male mating strategy is a perching sit-and-wait tactic and the species occupy woodland structures. In such circumstances males have relatively few opportunities to mate, male-female encounter rates may be relatively infrequent and the physical structure of the habitat allows females that adopt possum mate-rejection to escape from males by dropping into vegetation. We encourage further observations on this behaviour to allow a thorough analysis of its frequency amongst species in order to allow a phylogenetic analysis