Habitat connectivity, more than species’ biology, influences genetic differentiation in a habitat specialist, the short-eared rock-wallaby (Petrogale brachyotis)

It is difficult to assess the relative influence of anthropogenic processes (e.g., habitat fragmentation) versus species’ biology on the level of genetic differentiation among populations when species are restricted in their distribution to fragmented habitats. This issue is particularly problematic for Australian rock-wallabies (Petrogale sp.), where most previous studies have examined threatened species in anthropogenically fragmented habitats. The short-eared rock-wallaby (Petrogale brachyotis) provides an opportunity to assess natural population structure and gene flow in relatively continuous habitat across north-western Australia. This region has reported widespread declines in small-to-medium sized mammals, making data regarding the influence of habitat connectivity on genetic diversity important for broad-scale management. Using non-invasive and standard methods, 12 microsatellite loci and mitochondrial DNA were compared to examine patterns of population structure and dispersal among populations of P. brachyotis in the Kimberley, Western Australia. Low genetic differentiation was detected between populations separated by up to 67?km. The inferred genetic connectivity of these populations suggests that in suitable habitat P. brachyotis can potentially disperse far greater distances than previously reported for rock-wallabies in more fragmented habitat. Like other Petrogale species male-biased dispersal was detected. These findings suggest that a complete understanding of population biology may not be achieved solely by the study of fragmented populations in disturbed environments and that management strategies may need to draw on studies of populations (or related species) in undisturbed areas of contiguous habitat.     

Habitat selection by Canada lynx: making do in heavily fragmented landscapes

Habitat loss and fragmentation result in landscapes where high quality habitat patches are surrounded by matrix habitats of low and variable quality. For mobile species to persist in such landscapes, individual animals often rely on the high quality habitats but also use matrix habitats for supplemental resources or while moving between higher quality patches. Determining what habitat features animals select when in these matrix areas is important, as retaining desirable features in lower quality habitats may enable species persistence. We examine a population of US federally threatened Canada lynx (Lynx canadensis) in northcentral Washington, near the southwestern range limit, where lynx habitat is fragmented by topography, wildfires, and human impacts. We used Global Positioning System radio-collar data from 17 lynx in the North Cascade Mountains during 2007–2013 to explore lynx habitat use. We used Random Forest models to analyze core hunting, resting, and denning habitat, and the habitats lynx select while between patches of core habitat. While selecting core habitat, lynx used spruce (Picea engelmannii)-fir (Abies lasiocarpa), lodgepole pine (Pinus contorta), and mixed sub-boreal-Douglas fir (Pseudotsuga menziesii) forests, and avoided dry forests and forest openings including new burns. When not in core habitat, lynx used a wider range of habitats, including new burns where fire skips and residual trees offered cover. Our results show clearly that Canada lynx tolerate a wider range of habitats where they occupy fragmented landscapes. Consequently, maintaining animals in fragmented landscapes requires that we identify and conserve not only the core habitats a particular species selects, but also the habitat features animals use while in less suitable environments.     

A mosaic of opportunities? Spatio-temporal patterns of bat diversity and activity in a strongly humanized Mediterranean wetland

The Baixo Vouga Lagunar (BVL) landscape, in the Portuguese central-west coast, harbours a mosaic of wetland habitat types, interspersed by intensive and extensive agricultural fields, pastures, production forests and urban areas. In this study, we aimed to determine the species composition and the structure of the bat assemblages of the different habitats that constitute this heterogeneous landscape and to investigate seasonal changes in the patterns of bat diversity and activity across habitats. We acoustically sampled bats across 24 sampling sites representative of the eight main habitat types that shape the landscape—Bocage, forests, maize fields, marshlands, reed beds, rice fields, sea rushes and urban settlements. We compared bat richness, diversity and evenness across habitat types and seasons. We analysed habitat-specific and season-specific overall bat activity, and because habitat selection by bats is known to reflect morphological characters, foraging strategies and echolocation call structures, we also analysed the activity of individual species and of eco-morphological guilds. From 1,544 bat-passes recorded, we identified 12 species. Pipistrellus pygmaeus, Pipistrellus pipistrellus and Eptesicus serotinus/Eptesicus isabellinus were the most frequently recorded. Species composition and activity were similar across habitats, whilst exhibiting strong seasonal dynamics within habitats. Our results suggest that the mosaicism of the landscape provides several opportunities for bats, enabling them to explore different resources in distinct habitat patches. However, it may also reflect a forced exploitation of less optimal habitats and resources by bats, due to the scarcity of opportunities provided by fragmented landscapes.     

Population structure of pioneer specialist solitary bee Andrena vaga (Hymenoptera: Andrenidae) in central Europe: the effect of habitat fragmentation or evolutionary history?

Because patchiness of food sources or nesting opportunities frequently limits gene flow, specialists often exhibit distinct population structures in fragmented habitats. We studied the influence of habitat fragmentation on population structure in the solitary bee Andrena vaga, an early spring species that nests exclusively in sandy soil and feeds strictly on willows (Salix spp.). Because the homogenous habitat of the German floodplains, where the species was studied previously, resulted in the species’ weak population structure, we expected more structured populations in central Europe, where the sandy soils essential for nesting are highly fragmented. We analysed 387 females from 21 localities in the Czech Republic and Slovakia using nine microsatellite loci, and we inferred population structure using landscape genetics and Bayesian clustering methods. Contrary to our expectations, habitat fragmentation did not result in increased genetic isolation at the localities; however, two differentiated groups of localities, separated by a wide clinal zone of admixture, were detected within the study area. The observed pattern suggests that dispersive ability of A. vaga compensates the species dependence on unstable fragmented habitats. We propose that the population structure may mirror a secondary contact formed by the expansion of two populations that had been separated in the past. We emphasise the necessity of knowing the studied species’ population history before making conclusions concerning correlations between habitat and population structure, especially in areas of known suture zones created by the secondary contact of populations expanding from separate refugia.     

Is the matrix important to butterflies in fragmented landscapes?

The quality and extent of the ‘matrix’ in terrestrial fragmented landscapes may influence the persistence and behaviour of patch-associated fauna. Butterflies are a popular target group for fragmentation studies and represent an ideal assemblage to explore the impact and role of the matrix in patchy landscapes. To date, there has been no attempt to synthesise available research and assess the extent to which the matrix is included in studies of fragmented butterfly populations. Addressing this issue is important for improved understanding of habitat use in fragmented landscapes, and for the successful management and conservation of butterfly biodiversity. Our systematic review of 100 empirical research papers spans 50 years, and identifies how (and indeed if) the matrix is recognised in studies of butterfly populations in fragmented landscapes. We found that it was significantly more likely for studies not to include the matrix in their experimental design. This is of particular concern given 60 % of papers that excluded the matrix in their research did so in systems where the matrix was expected to contain resources of value for patch-associated species (as it was either a heterogeneous landscape or had similar structure to patches). Of the papers that did consider the matrix, 80 % (n = 24) reported a negative effect of the matrix on butterfly species and/or communities. Matrix effects may influence the survival and persistence of faunal groups in a world increasingly dominated by fragmented habitats. Our review suggests that future research should clearly define the matrix, and incorporate it in appropriate experimental designs.     

Experimental effects of habitat fragmentation on rove beetles and ants: patch area or edge?

The effects of habitat fragmentation may include the loss of species from isolated fragments or changes in species abundances among habitats that differ in area, structure, or edge characteristics. We measured the species richness and abundance of ground‐dwelling insects in a 1.14‐ha old field that was mowed to produce patches of unmowed vegetation which differed in size, degree of isolation, and the amount of habitat edge. Four treatments – ranging from unfragmented (169‐m²) to highly fragmented (1‐m²) patches – were replicated four times in a Latin square design, and insects were sampled twice during 1995 using 177 pitfall traps. Species richness showed a non‐monotonic response to fragmentation, with the fewest species occurring in the slightly fragmented treatment. Responses of rove beetles and ants, the most species‐rich and abundant taxa, respectively, were similar to the overall insect community but ants had a stronger and more consistent treatment effect in both sample months. Ordinations of ant and rove‐beetle assemblages using nonmetric multidimensional scaling showed that the slightly fragmented treatment differed from other treatments in species occurrence and abundance. The lower species richness in the slightly fragmented treatment was primarily due to a subset of ant and rove beetle species that showed a lower abundance than in other treatments, possibly because this treatment had the greatest amount of habitat edge. We hypothesize that the non‐monotonic species response to fragmentation was due to the differential effects of habitat edge on species movements across the habitat boundary between unmowed patches and mowed areas. A greater effect due to the amount of habitat edge rather than total patch area, at least among the range of patch sizes studied, suggests that the length of habitat edge may be quite important to the distribution and abundance of ground‐dwelling animals in fragmented habitats.     

Landscape configuration determines gene flow and phenotype in a flightless forest-edge ground-dwelling bush-cricket, Pholidoptera griseoaptera

Spatial configuration of habitats influences genetic structure and population fitness whereas it affects mainly species with limited dispersal ability. To reveal how habitat fragmentation determines dispersal and dispersal-related morphology in a ground-dispersing insect species we used a bush-cricket (Pholidoptera griseoaptera) which is associated with forest-edge habitat. We analysed spatial genetic patterns together with variability of the phenotype in two forested landscapes with different levels of fragmentation. While spatial configuration of forest habitats did not negatively affect genetic characteristics related to the fitness of sampled populations, genetic differentiation was found higher among populations from an extensive forest. Compared to an agricultural matrix between forest patches, the matrix of extensive forest had lower permeability and posed barriers for the dispersal of this species. Landscape configuration significantly affected also morphological traits that are supposed to account for species dispersal potential; individuals from fragmented forest patches had longer hind femurs and a higher femur to pronotum ratio. This result suggests that selection pressure act differently on populations from both landscape types since dispersal-related morphology was related to the level of habitat fragmentation. Thus observed patterns may be explained as plastic according to the level of landscape configuration; while anthropogenic fragmentation of habitats for this species can lead to homogenization of spatial genetic structure.     

Metacommunities of spiders in grassland habitat fragments of an agricultural landscape

Arthropod communities in fragmented agricultural landscapes depend on local processes and the interactions between communities in the habitat islands. We aimed to study metacommunity structure of spiders, a group that is known for high dispersal power, local niche partitioning and for engaging in species interactions. While living in fragmented habitats could lead to nestedness, other ecological traits of spiders might equally lead to patterns dominated either by species interactions or habitat filtering. We asked, which community pattern will prevail in a typical agricultural landscape with isolated patches of semi-natural habitats. Such a situation was studied by sampling spiders in 28 grassland locations in a Hungarian agricultural landscape. We used the elements of metacommunity structure (EMS) framework to distinguish between alternative patterns that reveal community organization. The EMS analysis indicated coherent species ranges, high turnover and boundary clumping, suggesting Clementsian community organization. The greatest variation in species composition was explained by local habitat characteristics, indicating habitat filtering. The influence of dispersal could be detected by the significant effect of landscape composition, which was strongest at 500 m. We conclude that dispersal allows spiders to respond coherently to the environment, creating similar communities in similar habitats. Consistent habitat differences, such as species rich versus species poor vegetation, lead to recognisably different, recurrent communities. These characteristics make spiders a predictable and diverse source of natural enemies in agricultural landscapes. Sensitivity to habitat composition at medium distances warns us that landscape homogenization may alter these metacommunity processes.     

Habitat patch size alters the importance of dispersal for species diversity in an experimental freshwater community

Increased dispersal of individuals among discrete habitat patches should increase the average number of species present in each local habitat patch. However, experimental studies have found variable effects of dispersal on local species richness. Priority effects, predators, and habitat heterogeneity have been proposed as mechanisms that limit the effect of dispersal on species richness. However, the size of a habitat patch could affect how dispersal regulates the number of species able to persist. We investigated whether habitat size interacted with dispersal rate to affect the number of species present in local habitats. We hypothesized that increased dispersal rates would positively affect local species richness more in small habitats than in large habitats, because rare species would be protected from demographic extinction. To test the interaction between dispersal rate and habitat size, we factorially manipulated the size of experimental ponds and dispersal rates, using a model community of freshwater zooplankton. We found that high‐dispersal rates enhanced local species richness in small experimental ponds, but had no effect in large experimental ponds. Our results suggest that there is a trade‐off between patch connectivity (a mediator of dispersal rates) and patch size, providing context for understanding the variability observed in dispersal effects among natural communities, as well as for developing conservation and management plans in an increasingly fragmented world.     

Life history strategy influences parasite responses to habitat fragmentation

Anthropogenic habitat use is a major threat to biodiversity and is known to increase the abundance of generalist host species such as rodents, which are regarded as potential disease carriers. Parasites have an intimate relationship with their host and the surrounding environment and it is expected that habitat fragmentation will affect parasite infestation levels. We investigated the effect of habitat fragmentation on the ecto- and endoparasitic burdens of a broad niche small mammal, Rhabdomys pumilio, in the Western Cape Province, South Africa. Our aim was to look at the effects of fragmentation on different parasite species with diverse life history characteristics and to determine whether general patterns can be found. Sampling took place within pristine lowland (Fynbos/Renosterveld) areas and at fragmented sites surrounded and isolated by agricultural activities. All arthropod ectoparasites and available gastrointestinal endoparasites were identified. We used conditional autoregressive models to investigate the effects of habitat fragmentation on parasite species richness and abundance of all recovered parasites. Host density and body size were larger in the fragments. Combined ecto- as well as combined endoparasite taxa showed higher parasite species richness in fragmented sites. Parasite abundance was generally higher in the case of R. pumilio individuals in fragmented habitats but it appears that parasites that are more permanently associated with the host’s body and those that are host-specific show the opposite trend. Parasite life history is an important factor that needs to be considered when predicting the effects of habitat fragmentation on parasite and pathogen transmission.     

Anthropogenic Habitats Facilitate Dispersal of an Early Successional Obligate: Implications for Restoration of an Endangered Ecosystem

Landscape modification and habitat fragmentation disrupt the connectivity of natural landscapes, with major consequences for biodiversity. Species that require patchily distributed habitats, such as those that specialize on early successional ecosystems, must disperse through a landscape matrix with unsuitable habitat types. We evaluated landscape effects on dispersal of an early successional obligate, the New England cottontail (Sylvilagus transitionalis). Using a landscape genetics approach, we identified barriers and facilitators of gene flow and connectivity corridors for a population of cottontails in the northeastern United States. We modeled dispersal in relation to landscape structure and composition and tested hypotheses about the influence of habitat fragmentation on gene flow. Anthropogenic and natural shrubland habitats facilitated gene flow, while the remainder of the matrix, particularly development and forest, impeded gene flow. The relative influence of matrix habitats differed between study areas in relation to a fragmentation gradient. Barrier features had higher explanatory power in the more fragmented site, while facilitating features were important in the less fragmented site. Landscape models that included a simultaneous barrier and facilitating effect of roads had higher explanatory power than models that considered either effect separately, supporting the hypothesis that roads act as both barriers and facilitators at all spatial scales. The inclusion of LiDAR-identified shrubland habitat improved the fit of our facilitator models. Corridor analyses using circuit and least cost path approaches revealed the importance of anthropogenic, linear features for restoring connectivity between the study areas. In fragmented landscapes, human-modified habitats may enhance functional connectivity by providing suitable dispersal conduits for early successional specialists.     

Variation in the thermal ecology of an endemic iguana from Mexico reduces its vulnerability to global warming

The persistence of reptile populations in a specific location is influenced by individuals’ capacity to regulate their body temperatures, among other factors. Anthropogenic climate change may pose a risk to the survival of ectothermic animals due to their dependence on external heat sources to thermoregulate. In this study, we calculated indices of thermal habitat quality, thermoregulatory precision, and thermoregulatory effectiveness for the endemic spiny-tailed iguana Ctenosaura oaxacana. We evaluated these indices and the thermoregulatory behavior of the iguanas in the four types of vegetation that provide the most favorable conditions for thermoregulation. We also performed our experiments during both the wet and dry seasons to capture the full range of thermal conditions available to C. oaxacana over the course of a year. Finally, we evaluated the potential niche for the iguana in the years 2020, 2050, and 2080. Thermoregulation depends on both seasonal and environmental factors in this species. We found that thermoregulation effectiveness in both wet and dry seasons depends not only on the thermal conditions of the immediate environment, but also on the cover vegetation and habitat structure available across the range of habitats the species uses. Thus, heterogeneous habitats with dispersed vegetation may be most suitable for this species’ thermoregulatory strategy. Likewise, niche modeling results suggested that suitable habitat for our study species may continue to be available for the next few decades, despite global warming tendencies, as long as cover vegetation remains unaltered. Our results suggest that thermoregulation is a complex process that cannot be generalized for all ectothermic species inhabiting a given region. We also found that temperature changes are not the only factor one must consider when estimating the risk of species loss. To understand the necessary thermal conditions and extinction risk for any ectothermic species, it is necessary to focus studies on the species’ general ecology.     

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.     

Mosquito Vector Diversity across Habitats in Central Thailand Endemic for Dengue and Other Arthropod-Borne Diseases

Recent years have seen the greatest ecological disturbances of our times, with global human expansion, species and habitat loss, climate change, and the emergence of new and previously-known infectious diseases. Biodiversity loss affects infectious disease risk by disrupting normal relationships between hosts and pathogens. Mosquito-borne pathogens respond to changing dynamics on multiple transmission levels and appear to increase in disturbed systems, yet current knowledge of mosquito diversity and the relative abundance of vectors as a function of habitat change is limited. We characterize mosquito communities across habitats with differing levels of anthropogenic ecological disturbance in central Thailand. During the 2008 rainy season, adult mosquito collections from 24 sites, representing 6 habitat types ranging from forest to urban, yielded 62,126 intact female mosquitoes (83,325 total mosquitoes) that were assigned to 109 taxa. Female mosquito abundance was highest in rice fields and lowest in forests. Diversity indices and rarefied species richness estimates indicate the mosquito fauna was more diverse in rural and less diverse in rice field habitats, while extrapolated estimates of true richness (Chao1 and ACE) indicated higher diversity in the forest and fragmented forest habitats and lower diversity in the urban. Culex sp. (Vishnui subgroup) was the most common taxon found overall and the most frequent in fragmented forest, rice field, rural, and suburban habitats. The distributions of species of medical importance differed significantly across habitat types and were always lowest in the intact, forest habitat. The relative abundance of key vector species, Aedes aegypti and Culex quinquefasciatus, was negatively correlated with diversity, suggesting that direct species interactions and/or habitat-mediated factors differentially affecting invasive disease vectors may be important mechanisms linking biodiversity loss to human health. Our results are an important first step for understanding the dynamics of mosquito vector distributions under changing environmental features across landscapes of Thailand.     

Evidence for evolutionary change associated with the recent range expansion of the British butterfly, Aricia agestis, in response to climate change

Poleward range expansions are widespread responses to recent climate change and are crucial for the future persistence of many species. However, evolutionary change in traits such as colonization history and habitat preference may also be necessary to track environmental change across a fragmented landscape. Understanding the likelihood and speed of such adaptive change is important in determining the rate of species extinction with ongoing climate change. We conducted an amplified fragment length polymorphism (AFLP)‐based genome scan across the recently expanded UK range of the Brown Argus butterfly, Aricia agestis, and used outlier‐based (DFDIST and BayeScan) and association‐based (Isolation‐By‐Adaptation) statistical approaches to identify signatures of evolutionary change associated with range expansion and habitat use. We present evidence for (i) limited effects of range expansion on population genetic structure and (ii) strong signatures of selection at approximately 5% AFLP loci associated with both the poleward range expansion of A. agestis and differences in habitat use across long‐established and recently colonized sites. Patterns of allele frequency variation at these candidate loci suggest that adaptation to new habitats at the range margin has involved selection on genetic variation in habitat use found across the long‐established part of the range. Our results suggest that evolutionary change is likely to affect species’ responses to climate change and that genetic variation in ecological traits across species’ distributions should be maximized to facilitate range shifts across a fragmented landscape, particularly in species that show strong associations with particular habitats.     

Range shifting on a fragmented landscape

Projected responses of species' to climate change have so far included few of the factors that are important determinants of species' distributions within its range. In this paper we utilise a spatially explicit cellular lattice, colonisation–extinction model to investigate the effect of habitat loss, fragmentation and species characteristics on range shifting in response to climate change. Contrary to the predictions of patch occupancy in static climate models we show that fragmentation can have a positive effect on species survival when species have high colonisation rates. For species with low colonisation rates aggregative behaviours prevent success on fragmented landscapes at high levels of habitat loss, and range shifting is more successfully achieved where habitat is correlated. At levels of habitat loss near the extinction threshold, less fragmented landscapes can facilitate range shifting even for the best colonisers. We discuss how imposing a climate window may reduce percolation routes and have implications for the area of usable habitat at any given level of habitat availability. We demonstrate the importance of landscape structure for range shifting dynamics and argue that management of reserve networks needs to consider the requirements of species with different life history characteristics.     

Reduced dispersal propensity in the wingless waterstrider Aquarius najas in a highly fragmented landscape

Dispersal behaviour of animals in fragmented habitats has generated intensive theoretical attention but empirical data on the evolution of dispersal are still relatively scarce. Theory predicts reduced dispersal propensity in small and isolated habitat patches. We tested these predictions in the waterstrider Aquarius najas, a wingless species with special habitat demands. Flightlessness constrains insect dispersal and as a stream specialist A. najas cannot survive on still water. Lakes therefore represent a dispersal barrier for this species. We measured dispersal propensity of the waterstrider A. najas which originated from ten fragmented populations. In the experiment, we transplanted laboratory-grown individuals to the field. We did not find differences between sex in dispersal propensity. However, we found that waterstriders that originated from small and isolated patches moved less than individuals from large and more continuous habitats. This suggests that the cost of dispersal over hostile surrounding habitats may be high. We conclude that a low likelihood of dispersal in A. najas is an adaptation to small and isolated stream habitats.     

Species–area models to assess biodiversity change in multi-habitat landscapes: The importance of species habitat affinity

Species–area relationships (SARs) are a common tool to assess the impacts of habitat loss on species diversity. Species–area models that include habitat effects may better describe biodiversity patterns; also the shape of the SAR may be best described by other models than the classical power model. We compared the fit of 24 SAR models, i.e. eight basic models using three approaches: (i) single-habitat models, (ii) multi-habitat models which account for the effect of the habitat composition on total species diversity (= choros models) and (iii) multi-habitat models which also account for the differential use of habitats by different species groups (= countryside models). We use plant diversity data from a multi-habitat landscape in NW Portugal. Countryside models had the best fit both when predicting species–area patterns of species groups and of total species richness. Overall, choros models had a better fit than single-habitat models. We also tested the application of multi-habitat models to land-use change scenarios. Estimates of species richness using the choros model only depended on the number of habitats in the landscape. In contrast, for the countryside model, estimates of species richness varied continuously with the relative proportion of the different habitat types in the landscape, and projections suggest that land-use change impacts may be moderated by a species’ ability to use multiple habitats in the landscape. We argue that the countryside SAR is a better model to assess the impacts of land-use changes than the single-habitat SAR or the choros model, as species often face habitat change instead of real habitat loss, and species response to change is contingent on their differential use of habitats in the landscape.     

Isolation from forest habitats reduces chances of the presence of <Emphasis Type="Italic">Osmoderma eremita</Emphasis> sensu lato (Coleoptera,Scarabaeidae) in rural avenues

Decline and fragmentation of natural habitats, such as old-growth forests, reduces their availability in the landscape. The solution to this problem for many forest-dwelling species, may be colonization of alternative habitats, such as parks, orchards or rural avenues, located in the highly fragmented agricultural landscape. Our main objective was to determine the effect of both habitat quality parameters and isolation from potential forest habitats, as primary habitats, on the occurrence of the hermit beetle (Osmoderma) in rural avenues in south-western Poland. The study was based on the results of an inventory of the species in 201 rural avenues within an area of approx. 30,000 km². Occurrence of the hermit beetle in such alternative habitats was affected by both habitat quality parameters and connectivity with suitable forest habitats. The species occurrence in an avenue was significantly positively affected by mean tree diameter and diversity of tree species, but probability of occurrence decreased as isolation of avenue from the deciduous forest increased. Moreover, in the study area the hermit beetle seemed to avoid alleys with a large proportion of Acer platanoides, Fraxinus excelsior and Populus spp. Spatially isolated roadside avenues have limited value in the preservation of the hermit beetle in the long term conservation management of the species. Conservation plans in such habitats should therefore take into account surrounding suitable habitats.     

The effects of habitat fragmentation on niche requirements of the marsh fritillary, Euphydryas aurinia, (Rottemburg, 1775) on calcareous grasslands in southern UK

The marsh fritillary, Euphydryas aurinia, has declined greatly in distribution across its range within Europe, resulting in its designation as a protected species under Annex II of the 1979 Bern Convention and the EC Habitats and Species Directive. The decline has been linked to a marked reduction in the extent of suitable calcareous and wet grassland habitats, habitats which have been lost through conversion of land to agriculture or urban areas, or reduced in quality due to inappropriate management. The UK is now one of the major strongholds for this butterfly in Europe, although much of the remaining habitat is small, isolated and highly fragmented. E. aurinia populations fluctuate greatly due to the combined effects of biotic (e.g. parasitoids) and abiotic (e.g. climate change) factors. We quantified the habitat associations of larval webs of E. aurinia on fragmented versus extensive (unfragmented) calcareous grassland habitat in southern England to test the hypothesis that habitat requirements of E. aurinia are more constrained within fragmented landscapes. Within both fragmented and unfragmented landscapes the quality and quantity of its main host plant in the UK, Succisa pratensis, was positively related to numbers of E. aurinia larval webs found. The sward height was also important at predicting the distribution of larval webs in both landscapes, although the heights were greater within sites in the unfragmented (≈20 cm) compared to fragmented (≈15 cm) landscape. We also found significant effects of elevation and the cover of bare ground on numbers of larval webs. Elevation was strongly correlated with the availability of host plant, whilst bare ground was only significant on sites within the fragmented landscape, showing a negative relationship with number of larval webs. Our results further emphasise the importance of not only maintaining the habitat quality of extant calcareous grassland sites for E. aurinia in the UK, but also increasing the size and connectivity of these sites to increase the chances and rate of (re)colonisation of unoccupied but suitable habitat. In addition, we show that the habitat requirements of E. aurinia on sites in a large unfragmented landscape may be less specific and thus require less extensive management than that required to create optimal conditions necessary at smaller, more isolated sites in fragmented landscapes.