How do landscape structure, management and habitat quality drive the colonization of habitat patches by the Dryad Butterfly (Lepidoptera : Satyrinae) in fragmented grassland?

Most studies dealing with species distribution patterns on fragmented landscapes focus on the characteristics of habitat patches that influence local occurrence and abundance, but they tend to neglect the question of what drives colonization of previously unoccupied patches. In a study of the dryad butterfly, we combined classical approaches derived from metapopulation theory and landscape ecology to investigate the factors driving colonization from a recent refugium. In three consecutive transect surveys, we recorded the presence and numbers of imagos in 27 patches of xerothermic grassland and 26 patches of wet meadow. Among the predictors affecting the occurrence and abundance of the dryad, we considered environmental variables reflecting (i) habitat patch quality (e.g., goldenrod cover, shrub density, vegetation height); (ii) factors associated with habitat spatial structure (patch size, patch isolation and fragmentation); and (iii) features of patch surroundings (100-m buffers around patches) that potentially pose barriers or provide corridors. Patch colonization by the dryad was strongly limited by the distance from the species refugium in the region; there was a slight positive effect of shrub density in this respect. Butterfly abundance increased in smaller and more fragmented habitat patches; it was negatively impacted by invasive goldenrod cover, and positively influenced by the density of watercourses in patch surroundings. Nectar plant availability was positively related to species abundance in xerothermic grassland, while in wet meadow the effect was the reverse. We conclude that dryad colonization of our study area is very recent, since the most important factor limiting colonization was distance from the refugium, while the habitat quality of target patches had less relevance. In order to preserve the species, conservation managers should focus on enhancing the quality of large patches and should also direct their efforts on smaller and more fragmented ones, including those with relatively low resource availability, because such habitat fragments have an important role to play for specialist species

Resource use in two contrasting habitat types raises different challenges for the conservation of the dryad butterfly Minois dryas

The suitability of any location for a given species is determined by the available resources. However, there are many species that occur in more than one habitat type and their successful conservation may be particularly difficult. The dryad Minois dryas, a locally endangered butterfly, occurs in two contrasting habitats-xerothemic and wet grasslands. We investigated the influence of various habitat characteristics, such as vegetation height, grass cover, proximity of shrubs, plant species composition, Ellenberg indices of trophic and microclimatic conditions, on the microhabitat selection by the species. The nectaring of randomly selected butterflies was observed and habitat characteristics were compared at random points within the meadow and at the butterfly’s nectaring and resting places. The butterflies generally preferred to stay close to shrubs and avoided invasive goldenrods. Thermal conditions and the availability of nectar plants were the factors limiting the dryad’s use of wet grassland. In xerothermic habitats grass cover affected the distribution of butterflies. Concerning the availability of larval host plants, wet meadows proved potentially more favourable, whereas nectar resources for adults were more abundant in xerothermic grasslands. Based on our findings, conservation strategies for this butterfly must differ in the two habitats. Rotational mowing in xerothermic grasslands and the removal of invasive goldenrods in wet grasslands are the recommended actions. At a larger spatial scale, a habitat mosaic composed of xerothermic and wet grasslands in close proximity would seem to be the most suitable areas for the conservation of the dryad

All natural habitat edges matter equally for endangered Maculinea butterflies

An obvious consequence of habitat fragmentation is an increasing role of habitat edges for species survival. Recently it has been suggested that the endangered butterfly Maculinea nausithous prefers forested edges of its meadow habitats. However, the prevalence of forests in the study area used for this analysis makes it impossible to distinguish whether the effect detected is a genuine preference for forest edges or a preference for any natural patch edges as opposed to patch interiors. We investigated habitat selection by Maculinea nausithous and Maculinea teleius occurring sympatrically at five habitat patches surrounded by mosaic landscape. Butterfly capture positions were marked with GPS and subsequently analysed with GIS software. Both species avoided the interiors of their patches and concentrated in the edge zone, but these preferences were visible only at three larger patches exceeding 1 ha in area. Among different types of edges those bordering densely built-up areas were avoided, whereas all natural edges (adjacent to forests, reeds or grasslands) were similarly used. We hypothesise that preferences towards natural patch edges, regardless of their type, can be explained by the spatial interactions between Maculinea butterflies and Myrmica ants they parasitise. Patch surroundings constitute refuge space for the ants, and hence their densities may be expected to be higher near patch edges. Our findings indicate the importance of patch surroundings for the persistence of Maculinea populations. Regretfully, current legal framework makes it difficult to protect patch surroundings, where neither priority species nor their habitats occur

Within-patch mobility and flight morphology reflect resource use and dispersal potential in the dryad butterfly Minois dryas

Knowledge of mobility is essential for understanding animal habitat use and dispersal potential, especially in the case of species occurring in fragmented habitats. We compared within-patch movement distances, turning angles, resting times, and flight-related morphological traits in the locally endangered butterfly, the dryad (Minois dryas), between its old populations occupying xerothermic grasslands and newly established ones in wet meadows. We expected that the latter group should be more mobile. Individuals living in both habitat types did not differ in their body mass and size, but those from xerothermic grasslands had wider thoraxes and longer wings, thus lower wing loading index (defined as body mass to wing length ratio). The majority of movements were short and did not exceed 10 m. Movement distances were significantly larger in males. However, there was no direct effect of habitat type on movement distances. Our results suggest that the dryads from xerothermic grasslands have better flight capabilities, whereas those from wet meadows are likely to invest more in reproduction. This implies that mobility is shaped by resource availability rather than by recent evolutionary history. Lower female mobility may have negative implications for the metapopulation persistence because only mated females are able to (re)colonise vacant habitat patches efficiently. Conservation efforts should thus be focused on maintaining large habitat patches that prevent stochastic local extinctions. Furthermore, the recommendation of promoting the exchange of individuals among patches through improving matrix permeability, as well as assisted reintroductions of the species into suitable vacant habitats should also improve its conservation

The challenges to modern nature conservation - butterflies as a model group

Motyle są modelową grupą zwierząt w badaniach z zakresu ochrony przyrody i ekologii krajobrazu. Wiele gatunków motyli zostało rozpoznanych jako gatunki wskaźnikowe lub parasolowe. Zainteresowanie motylami dało początek ochronie owadów i ochronie krajobrazu. W artykule przedstawiam współczesne zagrożenia dla bioróżnorodności na przykładzie motyli jako grupy modelowej. Wyjaśniam koncepcję fragmentacji siedlisk i pojęcie siedliska, których rozumienie jest niezbędne aby podejmować skuteczne akcje ochrony zagrożonych gatunków. Opisuję jak kształtuje się odpowiedź motyli na zmiany w środowisku wywołane przez człowieka i podaję zarys praktycznych działań dotyczących ochrony bioróżnorodności. Najtrudniejszym zadaniem dla biologów zajmujących się ochroną przyrody jest określenie komponentów wchodzących w skład siedlisk kluczowych gatunków. Istnieją dwa główne podejścia. Pierwsze wynika z klasycznej teorii metapopulacji i zakłada, że siedlisko jest niejednolicie rozmieszczone w krajobrazie jako płaty siedliska otoczone nieprzyjaznym środowiskiem zwanym matriks. Drugie podejście wywodzi się z koncepcji siedliska opartego na zasobach, która uwzględnia wszystkie możliwe zasoby potrzebne w czasie całego cyklu życiowego gatunku. Głównym i globalnym problemem w ochronie motyli jest fragmentacja siedlisk, która prowadzi do zmian w konfiguracji krajobrazu. Innymi zagrożeniami są zmiany w intensywności użytkowania gruntów, inwazje obcych gatunków roślin i zmiany klimatu. Zrozumienie tych zjawisk jest niezbędne dla efektywnej ochrony gatunków, zarówno w skali płatu siedliska jak i skali krajobrazu.Butterflies are a model group of animals in studies of conservation biology and landscape ecology. Many butterfly species are recognized as biodiversity indicators and umbrella species. The interest in butterflies was a foundation stone in insect conservation and landscape management. In this paper, I present the contemporary threats to biodiversity with butterflies as an exemplary model group. I explain the concepts of the habitat and habitat fragmentation, which understanding is necessary for successful conservation actions. I review the response of butterflies to the human-induced changes in the environment and propose practical conservation recommendations. The most difficult task for conservation biologists is to determine what is a habitat of the target species. There are two main approaches. The first arises from the classic metapopulation theory and it assumes that habitat is patchily distributed in landscape and habitat patches are surrounded by the inhospitable environment called matrix. The second approach is a resource-based habitat concept that considers all possible species requirements into account. The main global problem in conservation of butterflies is habitat fragmentation which leads to changes in configuration of landscape and habitat patches. Other major conservation issues are changes in the land use intensity, invasion of alien plants and climate change. An understanding of these phenomena is essential to efficient conservation of species both at the habitat patch and landscape scales

Mimicry and polymorphism in butterfly Papilio dardanus

Mimikra od wielu lat dostarcza złożonych problemów badawczych dotyczących zagadnień związanych z doborem naturalnym, a szczególnie z doborem płciowym i ewolucją mimikry. Teoria mimikry zakłada, że zwierzęta upodabniają się do innych niejadalnych gatunków aby zminimalizować presję wywieraną przez drapieżniki, które uczą unikać się danego typu ubarwienia ofiary. U pewnych gatunków motyli występuje mimikra ograniczona do samic. Mimikra Bataesa ograniczona do samic i polimorfizm zostały stosunkowo dobrze opisane u afrykańskiego motyla Papilio dardanus. Samice tego motyla upodabniają się do różnych niejadalnych gatunków (modeli), np. z rodziny Dannaidae. Polimorfizm kontrolowany jest przez nie mniej niż 11 alleli zlokalizowanych w jednym lokus. U P. dardanus znane są także samice andromorficzne, których rola nie została jednak poznana. W pracy przedstawiam hipotezy dotyczące ewolucji mimikry oraz hipotezy związane z polimorfizmem samic. Większość hipotez odnosi się do dobru płciowego, pozostałe dotyczą ekologiczno-fizjologicznego kompromisu (ang. trade-off) i korzyści z mimikry zależnych od frekwencji występowania modeli jak też form polimorficznych naśladowcy. Opisuję również możliwe drogi ewolucji mimikry. Ostatnie badania pokazują, że ptaki atakują częściej niejadalne ofiary, kiedy zagęszczenie ich populacji jest większe. Fakt ten jest niezgodny z hipotezą korzyści z mimikry zależnych od frekwencji, która jest uznawana z najbardziej trafną. Hipoteza unikania napastowania samic andromorficznych przez samce także nie wyjaśnia obecności tych forma samic w populacji.Mimicry theory provides a lot of problems involving natural selection, particularly sexual selection and evolutionary routes of mimicry types. In some butterflies there is a mimicry limited to females. The Batesian mimicry and resulting polymorphism limited to females is especially well known in Papilio dardamus butterfly. This polymorphism is controlled by 11 alleles at a single locus. Females mimic resemble to different inedible species of butterflies, for example those from family Danaidae. Moreover, in P. dardanus the andromorphic females are also known, the role of which has not been thoroughly explained. In this review, I summarize hypotheses concerning the evolution of the mimicry-related polymorphism in this butterfly. Recent studies shows that avian predators attack inedible preys more frequently when their population density is higher. This fact does not prove the hypothesis of the frequency-dependent advantage of mimicry. I also describe possible evolutionary routes of the mimicry. Female limited mimicry and monomorphic mimicry have been evolved by independent routes. It also seems that the hypothesis of sexual harassment avoidance does not explain the appearance of andromorphic females in Papilio dardamus