Dispersal in the Glanville fritillary butterfly in fragmented versus continuous landscapes: comparison between three methods

1. Habitat fragmentation may lead to natural selection on dispersal rate and other life‐history traits. Both theoretical analyses and empirical studies suggest that habitat fragmentation may select either for increased or decreased dispersal depending on the traits of the species and the characteristics of the landscape. 2. Dispersal and movement rates in Glanville fritillary butterflies (Melitaea cinxia) originating from a continuous landscape in China and from a highly fragmented landscape in Finland were compared using three different methods. 3. The methods included replicated mark‐release‐recapture (MRR) experiments conducted in the natural environments in China and Finland, tracking with harmonic radar of captive‐reared but free‐flying butterflies in a common environment in the field, and replicated common garden experiments in a large outdoor population cage. 4. The results were largely consistent, showing that butterflies from the more continuous landscape in China had a lower movement rate than butterflies originating from the fragmented landscape in Finland. Butterflies originating from newly‐established populations in Finland moved significantly longer distances than butterflies originating from old populations in Finland or from China, demonstrating significant intra‐specific variation in dispersal rate in Finland. These results are consistent with model predictions for the Glanville fritillary. 5. The tracking experiment revealed a result that would have been impossible to obtain with MRR experiments: movement rate was influenced by a significant interaction between population origin (China vs. Finland) and ambient air temperature.     

Pervasive effects of dispersal limitation on within- and among-community species richness in agricultural landscapes

Aim To determine whether the effect of habitat fragmentation and habitat heterogeneity on species richness at different spatial scales depends on the dispersal ability of the species assemblages and if this results in nested species assemblages. Location Agricultural landscapes distributed over seven temperate Europe countries covering a range from France to Estonia. Methods We sampled 16 local communities in each of 24 agricultural landscapes (16 km²) that differ in the amount and heterogeneity of semi‐natural habitat patches. Carabid beetles were used as model organisms as dispersal ability can easily be assessed on morphological traits. The proximity and heterogeneity of semi‐natural patches within the landscape were related to average local (alpha), between local (beta) and landscape (gamma) species richness and compared among four guilds that differ in dispersal ability. Results For species assemblages with low dispersal ability, local diversity increased as the proximity of semi‐natural habitat increased, while mobile species showed an opposite trend. Beta diversity decreased equally for all dispersal classes in relation to proximity, suggesting a homogenizing effect of increased patch isolation. In contrast, habitat diversity of the semi‐natural patches affected beta diversity positively only for less mobile species, probably due to the low dispersal ability of specialist species. Species with low mobility that persisted in highly fragmented landscapes were consistently present in less fragmented ones, resulting in nested assemblages for this mobility class only. Main conclusions The incorporation of dispersal ability reveals that only local species assemblages with low dispersal ability show a decrease of richness as a result of fragmentation. This local species loss is compensated at least in part by an increase in species with high dispersal ability, which obscures the effect of fragmentation when investigated across dispersal groups. Conversely, fragmentation homogenizes the landscape fauna for all dispersal groups, which indicates the invasion of non‐crop habitats by similar good dispersers across the whole landscape. Given that recolonization of low dispersers is unlikely, depletion of these species in modern agricultural landscapes appears temporally pervasive.     

Mobility-dependent effects on species richness in fragmented landscapes

In fragmented landscapes, mobility is an important trait for population persistence but the predictions on the relationship between habitat fragmentation and extinction risk are contradictory. Here, we test the effects of the two main aspects of fragmentation, patch area and isolation, on the species richness of groups of butterflies associated with semi-natural grasslands, differing in mobility. Total species richness increased with increasing patch area and with decreasing isolation, but the strength of these effects differed between mobility classes. The effect of patch area was strongest for the sedentary species, while the effect of isolation was only statistically significant for the mobile species. We interpret these results as evidence for a predominant influence of local processes on sedentary species, and an increasing influence of regional compared to local processes with increasing mobility. When groups of species respond differently to habitat loss and fragmentation this affects community composition, with potential implications for ecosystem processes. Similar effects can be expected for other traits than mobility, and this should be an important question for future studies.     

Barriers to dispersal of rain forest butterflies in tropical agricultural landscapes

Fragmentation of natural habitats can be detrimental for species if individuals fail to cross habitat boundaries to reach new locations, thereby reducing functional connectivity. Connectivity is crucial for species shifting their ranges under climate change, making it important to understand factors that might prevent movement through human‐modified landscapes. In tropical regions, rain forests are being fragmented by agricultural expansion, potentially isolating populations of highly diverse forest‐dependent species. The likelihood of crossing habitat boundaries is an important determinant of species dispersal through fragmented landscapes, and so we examined movement across rain forest‐oil palm plantation boundaries on Borneo by using relatively mobile nymphalid butterflies as our model study taxon. We marked 1666 individuals from 65 species, and 19 percent (100/527) of recaptured individuals crossed the boundary. Boundary crossing was relatively frequent in some species, and net movement of individuals was from forest into plantation. However, boundary crossing from forest into plantation was detected in less than 50 percent (12/28) of recaptured species and was dominated by small‐sized butterfly species whose larval host plants occurred within plantations. Thus, while oil palm plantations may be relatively permeable to some species, they may act as barriers to the movement of forest‐dependent species (i.e., species that require rain forest habitat to breed), highlighting the importance of maintaining forest connectivity for conserving rain forest species.     

Habitat complementarity and butterfly traits are essential considerations when mitigating the effects of exotic plantation forestry

Habitat loss threatens insect diversity globally. However, complementary vegetation types in remaining habitat increases opportunities for species survival. We assess the extent to which indigenous forest patches moderate the impact of exotic commercial afforestation on grassland butterflies. Butterflies were sampled in grassland along uncorrelated gradients of landscape-scale indigenous forest and plantation cover, while controlling for variation in local vegetation composition. We separately assessed responses by butterfly groups differing in habitat preference, larval diet, and mobility. There was no effect of landscape- or local-scale variables on species richness, but there was a strong interactive effect of forest and plantation cover on butterfly assemblage structure. The effect varied according to species traits. When forest cover was high, assemblages did not differ at different levels of plantation cover. However, plantation cover significantly influenced assemblage structure when forest cover was low. Grassland with limited forest cover in the protected area supported unique assemblages with high frequency of less mobile, specialized species with herbaceous larval host plants, whereas grassland with low forest cover near plantations had a prevalence of mobile, generalist species. A positive association between forest cover and butterflies with woody larval host plants suggests that indigenous forest patches improved the suitability of fragmented grassland for a subset of butterflies, emphasising the value of natural heterogeneity in transformed areas. However, certain butterfly traits associated with large, open grassland were under-represented in grassland between plantations, underscoring the importance of open areas in the broader landscape to conserve the full diversity of species.

     

Modularity along organism dispersal gradients challenges a prevailing view of abrupt transitions in animal landscape perception

A common property of landscapes and metacommunities is the occurrence of abrupt shifts in connectivity along gradients of individual dispersal abilities. Animals with short‐range dispersal capability perceive fragmented landscapes, but organisms moving across critical thresholds perceive continuous landscapes. This qualitative shift in landscape perception may determine several attributes of local communities and the dynamics of whole metacommunities. Modularity describes the existence in some communities of relatively high numbers of mutual connections favoring the movement of neighboring individuals (even when each individual is able to reach any patch in the landscape). Local patch linkages and metacommunity connectivity along gradients of dispersal ability have been reported frequently. However, the intermediate level of structure captured by modularity has not been considered. We evaluated landscape connectivity and modularity along gradients of individual dispersal abilities. Random landscapes with different degrees of cell aggregation and occupancy were simulated; we also analyzed ten real ecosystems. An expected, a shift in landscape connectivity was always detected; modularity consistently decreased gradually along dispersal gradients in both simulated networks and empirical landscapes. Neutral metacommunities within simulated landscapes demonstrated that modularity and connectivity may reflect landscape traits in the shaping of metacommunity diversity. Average beta‐diversity was strongly associated with modularity, particularly with low migration rates, while connectivity trends tracked changes in beta‐diversity at intermediate to high migrations rates. Consequently, while some species are able to perceive abrupt transitions in the landscape, many others probably experience a gradual continuum in landscape perception, contrary to predictions from previous analyses. Furthermore, the gradual behavior of modularity indicates that it may represent an exceptional early‐warning tool that measures system distance to tipping points. Our study highlights the multiple perceptions that different species may have of a single landscape and shows, for the first time, a theoretical and empirical relationship between landscape modularity, and metacommunity diversity.     

Higher mobility of butterflies than moths connected to habitat suitability and body size in a release experiment

Mobility is a key factor determining lepidopteran species responses to environmental change. However, direct multispecies comparisons of mobility are rare and empirical comparisons between butterflies and moths have not been previously conducted. Here, we compared mobility between butterflies and diurnal moths and studied species traits affecting butterfly mobility. We experimentally marked and released 2011 butterfly and 2367 moth individuals belonging to 32 and 28 species, respectively, in a 25 m × 25 m release area within an 11‐ha, 8‐year‐old set‐aside field. Distance moved and emigration rate from the release habitat were recorded by species. The release experiment produced directly comparable mobility data in 18 butterfly and 9 moth species with almost 500 individuals recaptured. Butterflies were found more mobile than geometroid moths in terms of both distance moved (mean 315 m vs. 63 m, respectively) and emigration rate (mean 54% vs. 17%, respectively). Release habitat suitability had a strong effect on emigration rate and distance moved, because butterflies tended to leave the set‐aside, if it was not suitable for breeding. In addition, emigration rate and distance moved increased significantly with increasing body size. When phylogenetic relatedness among species was included in the analyses, the significant effect of body size disappeared, but habitat suitability remained significant for distance moved. The higher mobility of butterflies than geometroid moths can largely be explained by morphological differences, as butterflies are more robust fliers. The important role of release habitat suitability in butterfly mobility was expected, but seems not to have been empirically documented before. The observed positive correlation between butterfly size and mobility is in agreement with our previous findings on butterfly colonization speed in a long‐term set‐aside experiment and recent meta‐analyses on butterfly mobility.     

Landscape context affects the relationship between local and landscape species richness of butterflies in semi‐natural habitats

Local species richness of butterflies can be expected to benefit from both local habitat properties as well as the availability of suitable habitats and source populations in the surrounding landscape. Whether local species richness is dependent on local or landscape factors can be assessed by examining the relationship between local and landscape species richness. Here we studied how local species richness is related to landscape‐level species richness in landscapes differing in agricultural intensity. The relationship was linear for field boundaries in intensively cultivated landscapes and non‐linear in less‐intensively cultivated landscapes. In landscapes containing semi‐natural grasslands (on average 4% of overall land‐use), the relationship was non‐linear for field boundaries, but linear when considering local species richness of the grasslands themselves. These results show that local factors are more important than landscape factors in determining local species richness in landscapes which contained semi‐natural grasslands. Local species richness was limited by landscape factors in intensively cultivated landscapes. This interpretation was supported by the relationship between local species richness and landscape‐scale average mobility and generalist percentage of butterfly assemblages. We conclude that the management of field boundary habitat quality for butterflies is expected to be most effective in landscapes with semi‐natural grasslands, the species composition of which in turn is dependent on the regional occurrence of grasslands. Based on our results, managing non‐crop habitats for the conservation of habitat specialists and species with poor mobility will be most efficient in regions where patches of semi‐natural grasslands occur.     

Species traits help explain butterfly habitat use in a tropical forest

1. When species can access all parts of the landscape, species-sorting metacommunity theory predicts that community composition depends on habitat choice and interactions with other species and the environment. These filtering processes can also depend on species' traits.
2. The authors investigated how traits mediate a species-sorting process in determining butterfly community composition in a naturally patchy landscape in the tropical Western Ghats, India. The authors asked, do traits mediate access to certain habitats and does seasonality affect these patterns? The authors surveyed 56 habitat patches in three habitat types: laterite plateau grasslands, ridge grassland, and moist-deciduous forest, in a 65-km² landscape.
3. Non-palatable butterflies showed similar occurrences across seasons and habitats, but palatable butterflies were less commonly encountered in open habitats in the dry season. Polyphagous butterflies occurred infrequently in the dry season in laterite habitats, potentially indicating emigration or diapause patterns are linked to diet breadth.
4. All species were present in all habitats, implying dispersal does not limit access to different habitat patches, consistent with the species-sorting metacommunity concept. Nevertheless, butterfly occurrence was strongly influenced by the interaction of mobility and habitat type with sedentary species occurring less often in low-resource open laterite patches than mobile species.
5. Species sorting is typically regarded as occurring directly through environmental filters, but here the authors suggest that the environmental filter acts through movement limitations. Studies integrating landscape heterogeneity and species characteristics will help us better understand metacommunities and species distributions in nature.

     

Transcriptome Analysis Reveals Signature of Adaptation to Landscape Fragmentation

We characterize allelic and gene expression variation between populations of the Glanville fritillary butterfly (Melitaea cinxia) from two fragmented and two continuous landscapes in northern Europe. The populations exhibit significant differences in their life history traits, e.g. butterflies from fragmented landscapes have higher flight metabolic rate and dispersal rate in the field, and higher larval growth rate, than butterflies from continuous landscapes. In fragmented landscapes, local populations are small and have a high risk of local extinction, and hence the long-term persistence at the landscape level is based on frequent re-colonization of vacant habitat patches, which is predicted to select for increased dispersal rate. Using RNA-seq data and a common garden experiment, we found that a large number of genes (1,841) were differentially expressed between the landscape types. Hexamerin genes, the expression of which has previously been shown to have high heritability and which correlate strongly with larval development time in the Glanville fritillary, had higher expression in fragmented than continuous landscapes. Genes that were more highly expressed in butterflies from newly-established than old local populations within a fragmented landscape were also more highly expressed, at the landscape level, in fragmented than continuous landscapes. This result suggests that recurrent extinctions and re-colonizations in fragmented landscapes select a for specific expression profile. Genes that were significantly up-regulated following an experimental flight treatment had higher basal expression in fragmented landscapes, indicating that these butterflies are genetically primed for frequent flight. Active flight causes oxidative stress, but butterflies from fragmented landscapes were more tolerant of hypoxia. We conclude that differences in gene expression between the landscape types reflect genomic adaptations to landscape fragmentation.     

Sex-biased dispersal in a rare butterfly and the implications for its conservation

The survival of many species may be dependent on their ability to exist in human-altered landscapes within metapopulations; in turn, metapopulation persistence is dictated by the ability of individuals to move effectively among patches to promote recolonization. The Taylor’s checkerspot butterfly (Euphydryas editha taylori) is a species that does not naturally occur in fragmented landscapes, yet it is now restricted to a handful of small isolated prairie habitats. Current recovery plans aim to establish a stable metapopulation; however, to date little is known about the species’ ability to move across the landscape. In 2010 and 2011, we conducted marking, tracking and boundary surveys to explore the movement dynamics of adults within two sites in Oregon, USA. Over the survey period, we marked 136 male butterflies, tracked 174 individuals and observed the behavior of 1,576 individual butterflies at site boundaries. Our study revealed a significant sex-bias in the movement dynamics of the Taylor’s checkerspot in both suitable habitat and surrounding matrix. Males were highly motile, whereas females appeared sedentary, rarely moving from their natal site. The limited dispersal behavior of females indicates that populations cannot persist naturally in a metapopulation and thus are at high risk of extinction. Based on our findings, we recommend that managers take proactive measures to increase or enable dispersal (including translocation) to existing and/or restored sites.     

Exploratory behavior,but not aggressiveness,is correlated with breeding dispersal propensity in the highly philopatric thorn-tailed rayadito

Studies on the relationship between behavioral traits and dispersal are necessary to understand the evolution of dispersal syndromes. Empirical studies have mainly focused on natal dispersal, even though behavioral differences between dispersers and philopatric individuals are suspected to hold through the whole life cycle, potentially affecting breeding dispersal propensity. Using capture–mark–recapture data and behavioral trials in a forest passerine, the thorn-tailed rayadito Aphrastura spinicauda, we describe inter-individual differences in exploratory behavior and aggressiveness, and investigate the relationship between those traits and breeding dispersal. Our study took place in Fray Jorge National Park, north-central Chile, where a relatively isolated population of rayaditos inhabits a naturally fragmented environment. We found that scores for behavioral traits were consistent between years. Exploratory behavior was similar between sexes, while males showed higher levels of aggression towards a conspecific male intruder. Only exploratory behavior was related to breeding dispersal propensity, with fast-exploring rayaditos being more likely to have dispersed between seasons. This finding provides indirect evidence for the existence of a dispersal strategy that could reduce dispersal costs in the fragmented landscape of Fray Jorge. To our knowledge, this is the first study documenting an association between breeding dispersal and exploratory behavior in a wild bird population. A longitudinal individual-based study will help determining whether this association constitutes a behavioral syndrome.     

Resource use of specialist butterflies in agricultural landscapes: conservation lessons from the butterfly Phengaris (Maculinea) nausithous

Most of the European grassland butterfly species are dependent on species rich grasslands shaped by low intensity farming. Conservation of these specialist species in agricultural landscapes relies on knowledge of their essential resources and the spatial distribution of these resources. In The Netherlands, the dusky large blue Phengaris (Maculinea) nausithous butterflies were extinct until their reintroduction in 1990. In addition, a spontaneous recolonization of road verges in an agricultural landscape occurred in 2001 in the southern part of The Netherlands. We analyzed the use of the essential resources, both host plants and host ants, of the latter population during the summers of 2003 and 2005. First we tested whether the distribution of the butterflies during several years could be explained by both the presence of host plants as well as host ants, as we expected that the resource that limits the distribution of this species can differ between locations and over time. We found that oviposition site selection was related to the most abundant resource. While in 2003, site selection was best explained by the presence of the host ant Myrmica scabrinodis, in 2005 it was more strongly related to flowerhead availability of the host plant. We secondly compared the net displacement of individuals between the road verge population and the reintroduced population in the Moerputten meadows, since we expected that movement of individuals depends on the structure of their habitat. On the road verges, butterflies moved significantly shorter distances than on meadows, which limits the butterflies in finding their essential resources. Finally we analyzed the availability of the two essential resources in the surroundings of the road verge population. Given the short net displacement distances and the adverse landscape features for long-distance dispersal, this landscape analysis suggests that the Phengaris population at the Posterholt site is trapped on the recently recolonized road verges. These results highlight the importance of assessing the availability of essential resources across different years and locations relative to the movement of the butterflies, and the necessity to careful manage these resources for the conservation of specialist species in agricultural landscapes, such as this butterfly species.     

Coupling inter-patch movement models and landscape graph to assess functional connectivity

Landscape connectivity is a key process for the functioning and persistence of spatially-structured populations in fragmented landscapes. Butterflies are particularly sensitive to landscape change and are excellent model organisms to study landscape connectivity. Here, we infer functional connectivity from the assessment of the selection of different landscape elements in a highly fragmented landscape in the Île-de-France region (France). Firstly we measured the butterfly preferences of the Large White butterfly (Pieris brassicae) in different landscape elements using individual release experiments. Secondly, we used an inter-patch movement model based on butterfly choices to build the selection map of the landscape elements to moving butterflies. From this map, functional connectivity network of P. brassicae was modelled using landscape graph-based approach. In our study area, we identified nine components/groups of connected habitat patches, eight of them located in urbanized areas, whereas the last one covered the more rural areas. Eventually, we provided elements to validate the predictions of our model with independent experiments of mass release-recapture of butterflies. Our study shows (1) the efficiency of our inter-patch movement model based on species preferences in predicting complex ecological processes such as dispersal and (2) how inter-patch movement model results coupled to landscape graph can assess landscape functional connectivity at large spatial scales.     

Gene flow simulations demonstrate resistance of long-lived species to genetic erosion from habitat fragmentation

Habitat fragmentation restricts the movement of individuals across a landscape. In terrestrial and aquatic systems, barriers to movement can modify population and community dynamics at local or regional scales. This study contrasted life history traits related to lifespan with habitat fragmentation to determine impacts on species population genetic structure in the Neuse River Basin, USA. For this, we simulated gene flow among evenly-spaced populations in a river network and tracked individual and population genetics for 200 years. The modeled scenarios represent a full cross between five life history strategies and four riverscapes representing varying degrees of fragmentation. The five life history strategies include species (based on freshwater mussels) with average lifespans ranging from 10 to 50 years and age at maturity from 2 to 6 years. The movement landscapes included a (1) panmictic, (2) stepping-stone landscape allowing movement to only neighboring populations during each dispersal event, (3) partially-fragmented landscape divided by dams currently in the network, and (4) fully-fragmented landscape. Results suggest species with shorter lifespans have higher population genetic structure in fragmented landscapes than species with longer lifespans. Furthermore, species with shorter lifespans in highly fragmented landscapes may be harboring genetic degradation or decline as allele fixation and loss. Although anthropogenic fragmentation of many river systems is only 100–200 years old, the simulation indicates that species can respond genetically in that period of time. Additionally, the time frame of the simulation suggests that genetic impacts of habitat fragmentation in some species present in the Neuse River Basin may not yet be manifesting and restoration activities could be successful.     

Inter‐individual variation in movement: is there a mobility syndrome in the large white butterfly Pieris brassicae?

1. One of the main drivers of the genesis and maintenance of biodiversity is mobility, i.e. the net result of the interaction between physiological performances (movement capacity) and behavioural decisions (movement decisions). Although several previous studies have found personality traits related to mobility, it is not yet clear whether mobility involves a real syndrome, i.e. whether individuals showing good movement capacity are also more likely to decide to move, and whether these inter‐individual differences are consistent across time. 2. The aim of the present study was therefore to disentangle the mechanisms underlying the maintenance of inter‐individual variation in mobility by measuring three traits related to mobility under experimental conditions in a butterfly species, and to test the existence of correlations between these traits. These measures implied movement capacity and movement decision. 3. It was shown that mobility‐related traits were (i) consistent across time, (ii) inter‐correlated, and (iii) dependent upon sex and morphology. 4. These results therefore suggest the existence of a mobility syndrome in a butterfly. Such findings highlight the necessity to accurately integrate inter‐individual variation (behavioural syndrome) in our comprehension of the evolution of movement strategies.     

Landscape structure shapes habitat finding ability in a butterfly

Land-use intensification and habitat fragmentation is predicted to impact on the search strategies animals use to find habitat. We compared the habitat finding ability between populations of the speckled wood butterfly (Pararge aegeria L.) from landscapes that differ in degree of habitat fragmentation. Naïve butterflies reared under standardized laboratory conditions but originating from either fragmented agricultural landscapes or more continuous forested landscapes were released in the field, at fixed distances from a target habitat patch, and their flight paths were recorded. Butterflies originating from fragmented agricultural landscapes were better able to find a woodlot habitat from a distance compared to conspecifics from continuous forested landscapes. To manipulate the access to olfactory information, a subset of individuals from both landscape types were included in an antennae removal experiment. This confirmed the longer perceptual range for butterflies from agricultural landscapes and indicated the significance of both visual and olfactory information for orientation towards habitat. Our results are consistent with selection for increased perceptual range in fragmented landscapes to reduce dispersal costs. An increased perceptual range will alter the functional connectivity and thereby the chances for population persistence for the same level of structural connectivity in a fragmented landscape.     

Frugivory,Post‐feeding Flights of Frugivorous Birds and the Movement of Seeds in a Brazilian Fragmented Landscape

Habitat fragmentation can break down the movement processes of frugivorous animals, thus influencing the relationship between plants and their seed dispersers by altering the number and identity of seed dispersers, and their relative contribution to seed dispersal. We studied the assemblages of frugivorous birds, their composition, species richness, and visitation rates to fruiting plants growing in the different landscape elements (forest fragments, live fences, and trees isolated in pastures) embedded in a Brazilian fragmented, agricultural landscape. By following the post‐feeding movements of frugivorous birds, we inferred the direction of seed movement from and to each of these landscape elements. Fruiting trees growing at different landscape elements were visited by frugivorous birds at similar rates. Isolated trees attracted a greater and distinct bird assemblage than trees in forest fragments or live fences. Judging by the post‐feeding flights of birds, the seeds of isolated trees were the most likely to reach all the landscape elements considered, but the contribution of isolated trees to the seeds falling in forested habitats or pastures depended on their degree of isolation. A few bird species were able to move widely, visiting fruiting plants in all landscape elements, and promoting long‐distance dispersal for plants. These few birds are of special interest because they are mobile links that connect habitats in fragmented landscapes with their seed dispersal services. Abstract in Spanish is available at http://www.blackwell‐synergy.com/loi/btp .     

Local predation risk and matrix permeability interact to shape movement strategy

In fragmented landscapes, the reduced connectivity among patches drives the evolution of movement strategies through an increase of transience costs. Reduced movements may further alter heterogeneity in biotic and abiotic conditions experienced by individuals. The joint action of local conditions and matrix permeability may shape emigration decisions. Here, we tested the interactive effects of predation risk and matrix permeability on movement propensity, movement costs and movers’ phenotype in the common toad Bufo bufo. In a full‐crossed experimental design, we assessed the movement propensity of juveniles in three connectivity treatments (from poorly to highly permeable matrix), with or without predation risk in their living patch. We also assessed the relationships between movement propensity and morphological traits (i.e. body and leg length) and how it affected the movement cost (i.e. mass loss). Movement propensity increased in presence of predation risk, while matrix permeability had no effect. However, matrix permeability interacted with predation risk to influence movers’ phenotype and the physiological cost they endured while moving. In particular, a well‐known movement syndrome in toads (i.e. movement propensity positively related to longer legs) depended on the interaction between matrix permeability and predation risk and resulted in differences in mass loss among matrix types. Movers lost more mass on average than residents except when they also displayed longer legs or when they crossed the most permeable matrix in the presence of predation risk. Our results show that matrix permeability shapes the physiological cost of dispersal by changing the identity of individuals moving away from local conditions. As the movers’ phenotype can importantly alter (meta)population dynamics, context‐dependency of dispersal syndromes should be considered in studies predicting the functioning of human‐altered natural systems.     

Dispersal-related life-history trade-offs in a butterfly metapopulation

1. Recent studies on butterflies have documented apparent evolutionary changes in dispersal rate in response to climate change and habitat change. These studies often assume a trade-off between dispersal rate (or flight capacity) and reproduction, which is the rule in wing-dimorphic species but might not occur equally in wing-monomorphic species such as butterflies. 2. To investigate the relationship between dispersal rate and fecundity in the Glanville fritillary butterfly Melitaea cinxia we recorded lifetime individual movements, matings, ovipositions, and maximal life span in a large (32 x 26 m) population cage in the field. Experimental material was obtained from 20 newly established and 20 old local populations within a large metapopulation in the Aland Islands in Finland. 3. Females of the Glanville fritillary from newly established populations are known to be more dispersive in the field, and in the cage they showed significantly greater mobility, mated earlier, and laid more egg clutches than females from old populations. The dispersive females from new populations exhibited no reduced lifetime fecundity in the cage, but they had a shorter maximal life span than old-population females. 4. These results challenge the dispersal-fecundity trade-off for nonmigratory butterflies but instead suggest a physiological trade-off between high metabolic performance and reduced maximal life span. High metabolic performance may explain high rates of dispersal and oviposition in early life. 5. In fragmented landscapes, an ecological trade-off exists between being more dispersive and hence spending more time in the landscape matrix vs. having more time for reproduction in the habitat. We estimate with a dispersal model parameterized for the Glanville fritillary that the lifetime egg production is 4% smaller on average in the more dispersive butterflies in a representative landscape, with much variation depending on landscape structure in the neighbourhood of the natal patch, from--26 to 45% in the landscape analysed in this paper.