The importance of unique populations for conservation: the case of the Great Orme’s Head grayling butterfly Hipparchia semele (Linnaeus, 1758) (Lepidoptera: Satyrinae)

Small populations with unusual characteristics subject to extreme conditions provide opportunities for exploring adaptability in the face of environmental changes. Two sets of data have been examined to determine how unusual is the population of Hipparchia semele on the Great Orme’s Head, North Wales, compared with other sites in the UK. The population on the Great Orme is shown to have unique features, including significantly reduced wing expanse and wing ocellation and extreme flight period characteristics. Analyses of flight period data from the UK Butterfly Monitoring Scheme (UKBMS) using over a 100 sites reveals that, although the Great Orme population is one of a number of sites from the Channel Islands to northern Scotland with an early mean flight period, it has by far the earliest flight period and longest flight period of all populations—the latter raising the mean flight period date. Furthermore the unique characteristics of H. semele on the Orme may well be underestimated, inasmuch as sampling of individuals for the phenotype study is incomplete, including only the area along the North Wales coast into Cheshire, while the UKBMS transect is restricted to the south-west portion of the headland. Unique populations are often accorded focused conservation effort; especially potential flagship species in decline as in the case of British H. semele. As the Great Orme population presents a rare opportunity for studying adaptations in an extreme local environment, particularly considering current projections for climate changes, we advocate further research and attention being given to this unusual population

Butterfly abundance is determined by food availability and is mediated by species traits

1. Understanding the drivers of population abundance across species and sites is crucial for effective conservation management. At present, we lack a framework for predicting which sites are likely to support abundant butterfly communities. 2. We address this problem by exploring the determinants of abundance among 1111 populations of butterflies in the UK, spanning 27 species on 54 sites. Our general hypothesis is that the availability of food resources is a strong predictor of population abundance both within and between species, but that the relationship varies systematically with species’ traits. 3. We found strong positive correlations between butterfly abundance and the availability of food resources. Our indices of host plant and nectar are both significant predictors of butterfly population density, but the relationship is strongest for host plants, which explain up to 36% of the inter-site variance in abundance for some species. 4. Among species, the host plant–abundance relationship is mediated by butterfly species traits. It is strongest among those species with narrow diet breadths, low mobility and habitat specialists. Abundance for species with generalist diet and habitat associations is uncorrelated with our host plant index. 5. The host plant–abundance relationship is more pronounced on sites with predominantly north-facing slopes, suggesting a role for microclimate in mediating resource availability. 6. Synthesis and applications. We have shown that simple measures can be used to help understand patterns in abundance at large spatial scales. For some butterfly species, population carrying capacity on occupied sites is predictable from information about the vegetation composition. These results suggest that targeted management to increase host plant availability will translate into higher carrying capacity. Among UK butterflies, the species that would benefit most from such intervention have recently experienced steep declines in both abundance and distribution. The host plant–abundance relationship we have identified is likely to be transferrable to other systems characterized by strong interspecific interactions across trophic levels. This raises the possibility that the quality of habitat patches for specialist species is estimable from rapid assessment of the host plant resource

Changes in butterfly distributions: a simple correction for bias caused by sub-sampling of atlas records makes no difference to BAP status

In order to compare two sets of butterfly atlas data for the U.K. contrasting in number of records, a process of sub-sampling has been applied by Butterfly Conservation UK. This procedure has been criticised on two counts by Barbour, first on the basis of being taken to an excessive level; secondly, for creating bias in trends (losses, gains) among species. The present paper provides a simple correction for the second issue resulting from potential bias created by sub-sampling of records to determine incidence within 10 km squares. It demonstrates that any bias has not influenced the Biodiversity Action Plan status of butterflies in the U.K

Ecology of butterflies in Europe – where are we now and where to go?

Due to the attractiveness of butterflies, and their usefulness as model systems for biological questions, there has been a considerable amount of material written on butterfly biology, largely in Europe. This book synthesizes all relevant and recent knowledge in the field, which is a must for those making use of this taxonomic group as a model system. It is divided into five major parts which deal with habitat use, population ecology and genetics, evolutionary ecology, distribution and phylogeny, and global change and conservation. There are growing numbers of scientific projects and networks in Europe in which the use of butterflies as tools and targets for conservation is central, and application of knowledge is closely related to European cultural landscapes. However, the chapters can also be applied to a wide geographic scope. Written by an international team of experts, this timely book is suitable for students, researchers and enthusiasts

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

When is a habitat not a habitat? Dramatic resource use changes under differing weather conditions for the butterfly Plebejus argus

A key to conserving organisms is identification of the habitat bounds and essential resources within them. In population studies (metapopulations) of phytophagous arthropods it is tacitly assumed that habitat bounds portray short-term stability and that habitat is largely synonymous with hostplant areas or with a single vegetation unit comprising hostplants; structural components are usually ignored. We test these assumptions by monitoring the behaviour and relative abundance of Plebejus argus (L.) (Lepidoptera: Lycaenidae) in relation to changing weather conditions in two patches of a North Wales metapopulation for the butterfly. Our findings confirm the importance of structural habitat components. P. argus density is higher in the vicinity of shrubs which are used for roosting, resting, basking, mate location and shelter. A dominant proportion of the population adopts shrub areas in cooler, cloudy and windy weather. In warmer, sunnier and calmer conditions, the butterfly spends longer in flight and moves out onto calcareous heath dominated by hostplants. In doing so, an increasing, even dominant, proportion of the population occupies exposed slopes adjacent to and above shrub covered areas associated with the hostplant. In effect, the habitat bounds appear to change with conditions on scales of days and hours. What part of a landscape may be defined as a habitat, and what part of it may appear to be most important for an organism, depends on just when and where surveys are carried out. We argue that for correct delineation of habitats attention needs to be given to resource use in different conditions. In the face of enhanced global warming, a broad view should be taken of arthropod habitats that considers the resources required for varying conditions

Identifying zones of phenetic compression in West Mediterranean butterflies (Satyrinae): Refugia, invasion and hybridization

[Aim] Distinct insular populations are generally considered important units for conservation. In island-mainland situations, unidirectional introgressive gene flow from the most abundant, typically continental, populations into the smaller island populations can erase native insular genetic units. As an indication of threat, the concept of phenetic slope is developed, a measure proportional to differentiation and to geographical proximity. [Location] The Western Mediterranean, including the following islands: Sardinia, Sicily, Corsica, Balearics, circum-Italian, circum-Sicilian and circum-Sardo-Corsican archipelagos. Eastern Europe is included for comparison. [Methods] Geometric morphometrics was applied to 2392 male genitalia of seven butterfly species groups. Geographic Information System techniques were used to depict the pattern in the distribution of morphotypes. The slope of variation in genital shape was computed to highlight geographical areas showing abrupt morphological changes. Correlation analyses were performed between the mean slope values across sea straits separating islands and nearest sources and ecological traits of the species that underlie their colonization and migration capacity. [Results] Phenetic slope analysis has revealed that the strait of Messina and the northern Tyrrhenian Sea support particularly contrasting populations. In these areas, mean slopes for species also correlated with certain ecological traits of the species. Sardinia emerges as the most stable refugium for ancestral mediterranean populations. [Main conclusions] There is strong support for the hypothesis that Italy has experienced invasion by populations from Eastern Europe with postglacial expansion of these populations across Italy. However, propagules are impeded from invading islands by the expanse of sea straits. Even so, sea straits are not invariably barriers. Our results suggest that wind direction in combination with habitat occupancy may have maintained ancestral insular populations in key locations distinguished by phenetic compression. We conclude that native insular populations acting as barriers to introgression in the areas showing particularly steep phenetic slopes deserve attention in conservation programmes. © 2012 Blackwell Publishing Ltd.Support was provided by the Spanish Ministerio de Ciencia e Innovación project CGL2010-21226/BOS to R.V., L.D. and V.D., by a postdoctoral fellowship from the Wenner-Gren Foundation Sweden to V.D., and by the project ‘Definizione dello status di conservazione delle falene e della malacofauna terrestre dell’Arcipelago Toscano’ to L.D.Peer Reviewe

Mud-puddling aggregation behaviour in Pieris napi (Linnaeus, 1758) (Lepidoptera: Pieridae): does polyandry and large spermatophore mass transfer lead to increased investment in mud-puddling?

Mud-puddling aggregations of Pieris napi have been recorded more frequently than of other butterfly species in the U.K. Attention is focused on the factors, such as spermatophore mass and polyandry, likely to induce mud-puddling in this species particularly. Distinctive spatial patterns in mud-puddling aggregation behaviour are highlighted as a potentially valuable topic for future research

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

The relative exploitation of annuals as larval host plants by European butterflies

Theoretically, Lepidoptera should be able to adapt to using annuals as larval host plants through increased development rates and migration capacity. Even so, we show that annuals are used less frequently as host plants than expected among British and continental European butterflies. In particular, no example has been found of a European butterfly monophagous on an annual plant over its entire range. Use of annuals is proportionately greater among species that exploit increasing numbers of host plants and among subsidiary host plants than among primary (main) host plants. Annuals as host plants change status as habitat components with changes in species' spatial dynamics. The statistical findings point to perennials as providing host plant refuges, whereas the few case examples of site monophagy suggest that annuals can become valuable complementary resources during range extensions such as those currently associated with climatic warming. Annuals are more likely to be used in highly restricted circumstances, when environmental conditions allow the plants to persist over prolonged periods (i.e. when they are behaving like biennials) or when their spatial predictability is high because of low seed dispersal