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Human‐induced rapid environmental change (HIREC) is creating environments deviating considerably from natural habitats in which species evolved. Concurrently, climate warming is pushing species' climatic envelopes to geographic regions that offer novel ecological conditions. The persistence of species is likely affected by the interplay between the degree of ecological novelty and phenotypic plasticity, which in turn may shape an organism's range‐shifting ability. Current modelling approaches that forecast animal ranges are characterized by a static representation of the relationship between habitat use and fitness, which may bias predictions under conditions imposed by HIREC. We argue that accounting for dynamic species‐resource relationships can increase the ecological realism of range shift predictions. Our rationale builds on the concepts of ecological fitting, the process whereby individuals form successful novel biotic associations based on the suite of traits they carry at the time of encountering the novel condition, and behavioural plasticity, in particular learning. These concepts have revolutionized our view on fitness in novel ecological settings, and the way these processes may influence species ranges under HIREC. We have integrated them into a model of range expansion as a conceptual proof of principle highlighting the potentially substantial role of learning ability in range shifts under HIREC. [ABSTRACT FROM AUTHOR]

For small ectotherm species, dealing with microclimatic variation during sensitive stages of their development is a critical component of their ecological interactions within and among different landscape settings. However, it is often unknown whether the use of habitats in different landscape settings may affect microclimatic conditions at the level of microhabitats (e.g., at host plants for herbivorous insects). As opposed to standard ecological monitoring experiments, we aim to identify the microclimatic variables that accurately represent the environment in which a small arthropod spends most of its life. As a case study, we selected grassy sites that corresponded to the microhabitat of grass‐feeding insects in general, and larvae of the butterfly Pararge aegeria in particular, as this insect recently expanded its habitat use from forest (edges) to agricultural and urban environments. We tested the extent to which local microclimates and microclimatic buffering capacity differed between tufts of grass in forest and in two anthropogenic (i.e., agricultural and urban) landscape settings by measuring microclimatic variables with sensors at the level of the grasses. We compared temperature, relative humidity, and vapor pressure deficit (VPD) during an exceptionally warm and dry summer period with parallel data from weather stations and tested for differences between microclimatic profiles among the three landscape settings. Microclimatic conditions correspond only partly to variables based on weather station data. Differences are particularly significant for relative humidity and VPD, but not for day and night temperatures. Effects of canopy openness on the variability of microclimatic variables are landscape‐specific. Host plants in agricultural settings experience strong microclimatic fluctuations and low short‐term variability in VPD. In urban settings, urban heat island effects increase night temperature but also show microclimatic buffering effects similar to the ones in forest settings. Our findings stress the functional implications of landscape‐specific microclimatic profiles at the appropriate organism‐centered scale. We discuss the significance of such microclimatic profiles for ecological studies dealing with ectotherms under climate and land use change. [ABSTRACT FROM AUTHOR]

This is a commentary on Hodgson et al., 2022, https://doi.org/10.1111/gcb.16220 [ABSTRACT FROM AUTHOR]

1. Butterflies rely on suitable weather conditions for thermoregulation during active behaviour. While non‐sunny conditions are known to reduce time spent in active flight, detailed behavioural data on how variable microclimatic conditions affect decision making in specific behavioural contexts (e.g. habitat exploration, dispersal, mating, basking, oviposition) is often lacking. 2. We addressed the influence of direct sunlight on females of the Speckled wood butterfly (Pararge aegeria) that were motivated to oviposit. To test this, we observed gravid butterflies one by one in (1) a cage within a greenhouse, where temperature was kept high all the time, and (2) an outdoor cage under uncontrolled weather conditions. 3. Our results show that butterflies almost exclusively oviposit under direct sunlight. Surprisingly, results were similar in the warm within‐greenhouse cage, where activity remained high but oviposition never occurred during fully clouded conditions. 4. These results suggest that ovipositing butterflies require sunlight not only for thermoregulation. We hypothesise that direct sunlight benefits the ovipositing female by exposing more clearly the microclimatic variation of potential oviposition sites in the herbaceous layer of the vegetation. Heliophily during oviposition and pre‐oviposition exploration may apply to a range of microclimate‐sensitive species, particularly those living in microclimatically heterogeneous habitats. This warrants novel sensory ecological research, which will further improve our understanding of insect functional habitats. [ABSTRACT FROM AUTHOR]

Polylepis forests are endemic to the high‐Andes, with trees characterized by multi‐layered, exfoliating bark‐providing protection against harsh, high‐elevation conditions, both for individual trees and the wide array of organisms dependent on them. However, Polylepis habitat has suffered severe human‐induced land conversion and currently mainly occurs as fragmented remnants only. Here, we studied the effects of fragment size on local ambient temperature and on biomass of bark and its bark‐dwelling arthropods. We did so by comparing multiple samples at the edge and interior of both large and small fragments, while also accounting for branch size, tree width, and tree structure. Because arthropod biomass is likely to impact higher trophic levels, we also studied abundance and foraging behavior of two bird species specialized on Polylepis forest. We show that arthropod biomass was relatively higher in wider, larger trees, which were preferred for foraging by both bird species. Moreover, we show that small forest fragments are not only environmentally less buffered but are also characterized by lower amounts of bark and lower densities of bark‐dwelling arthropods than larger fragments. Our study highlights the conservation value of large trees. Also, we advise it is now timely to test to what degree restoration efforts to increase fragment size could mitigate the negative effects of reduced arthropod biomass for higher trophic levels of endemic specialist insectivores. [ABSTRACT FROM AUTHOR]

Poleward range shifts under climate change involve the colonization of new sites and hence the foundation of new populations at the expanding edge. We studied oviposition site selection in a butterfly under range expansion (Lycaena dispar), a key process for the establishment of new populations. We described and compared the microhabitats used by the species for egg laying with those available across the study sites both in edge and in core populations. We carried out an ecological niche factor analysis (ENFA) to estimate (1) the variety of microhabitats used by the butterfly for egg laying (tolerance) and (2) the extent to which these selected microhabitats deviated from those available (marginality). Microhabitat availability was similar in edge and core populations. Ambient temperature recorded at the site level above the vegetation was on average lower at core populations. In contrast with what is often assumed, edge populations did not have narrower microhabitat use compared to core populations. Females in edge populations even showed a higher degree of generalism: They laid eggs under a wider range of microhabitats. We suggest that this pattern could be related to an overrepresentation of fast deciding personalities in edge populations. We also showed that the thermal time window for active female behavior was reduced in edge populations, which could significantly decrease the time budget for oviposition and decrease the threshold of acceptance during microhabitat selection for oviposition in recently established populations. [ABSTRACT FROM AUTHOR]

Most behavioural traits show plastic responses to changes in internal or external conditions. Similarly, animal personality is not necessarily fixed during an individual's lifetime, leading to age‐related changes. Both individual plasticity (i.e., within‐individual effect) and non‐random selective (dis)appearance of behavioural types (i.e., between‐individual effect) may contribute to age‐related changes observed at the population level. Here, we investigated how boldness changes with age in a woodland population of the Speckled wood butterfly (Pararge aegeria L.) using a capture–mark–recapture approach. We used wing wear as an index for age and we show that fresh individuals are bolder than worn individuals. Using the subsample of recaptured butterflies, we found that this pattern is most likely driven by individual plasticity. Our design also allowed us to explore some aspects of the species' spatial ecology and how it relates to personality. We found no relationship between boldness and net displacement between successive captures, a finding which we discuss within a movement ecology framework. [ABSTRACT FROM AUTHOR]

Aim: Niche‐based models often ignore spatial variation in the climatic niche of a species across its occupied range and the related variation in the response to changing climate conditions. This assumption may lead to inaccurate predictions of species distribution shifts under climate change. Models have been developed to address this issue, but most of them depend upon prior knowledge on evolutionary lineages, phenotypic traits or ecological processes underlying local adaptation or adaptive plasticity. As such information is often lacking, these models are not frequently used to predict distribution shifts for many species. This limits our ability to explore general patterns of change across species. Innovation: Here, we propose a modelling framework that can be applied across a large sample of species to assess their distribution shifts under future climate while exploring the effect of intraspecific spatial variation in the response to climate conditions. The proposed approach does not require a detailed understanding of the processes underlying such variation. The geographical distribution of a species is split into spatial subsets along the gradient of occupied climate conditions. These subsets are considered as proxies for intraspecific spatial niche variation. Local models are built with each subset and their predictions are assembled across the study area under different dispersal assumptions. Using European butterflies as an example, we show that this approach can be used to explore the uncertainty about predicted distribution shifts arising from intraspecific spatial variation in sensitivity and response to changing climate conditions. Main conclusions: Our modelling approach is not intended to replace advanced modelling methods based on species‐specific knowledge of ecological and evolutionary processes, but it is useful as an exploratory tool to detect species for which detailed information on intraspecific responses to climate conditions is likely to make a difference for prediction of future distribution shifts. [ABSTRACT FROM AUTHOR]

Species distribution models analyse how species use different types of habitats. Their spatial predictions are often used to prioritize areas for conservation. Individuals may, however, prefer settling in habitat types of low quality compared to other available habitats. This ecological trap phenomenon is usually studied in a small number of habitat patches and consequences at the landscape level are largely unknown. It is therefore often unclear whether the spatial pattern of habitat use is aligned with the behavioural decisions made by the individuals during habitat selection or reflects actual variation in the quality of different habitat types. As species distribution models analyse the pattern of occurrence in different habitats, there is a conservation interest in examining what their predictions mean in terms of habitat quality when ecological traps are operating. Previous work in Belgium showed that red‐backed shrikes Lanius collurio are more attracted to newly available clear‐cut habitat in plantation forests than to the traditionally used farmland habitat. We developed models with shrike distribution data and compared their predictions with spatial variation in shrike reproductive performance used as a proxy for habitat quality. Models accurately predicted shrike distribution and identified the preferred clear‐cut patches as the most frequently used habitat, but reproductive performance was lower in clear‐cut areas than in farmland. With human‐induced rapid environmental changes, organisms may indeed be attracted to low‐quality habitats and occupy them at high densities. Consequently, the predictions of statistical models based on occurrence records may not align with variation in significant population parameters for the maintenance of the species. When species expand their range to novel habitats, such models are useful to document the spatial distribution of the organisms, but data on population growth rates are worth collecting before using model predictions to guide the spatial prioritization of conservation actions. [ABSTRACT FROM AUTHOR]

Aim: We test whether urbanization drives biotic homogenization. We hypothesize that declines in abundance and species diversity of aerial insects are exacerbated by the urbanization‐driven loss of species with low habitat generalism, mobility and warm‐adaptedness. We predict this homogenization to be more pronounced for nocturnal taxa, and at wider scales for mobile taxa. Location: Belgium. Time period: Summers 2014–2015. Major taxa studied: Lepidoptera. Methods: We compare communities along urbanization gradients using a shared, replicated and nested sampling design, in which butterflies were counted within 81 grassland and macro‐moths light‐trapped in 12 woodland sites. We quantify taxonomic and functional community composition, the latter via community‐weighted means and variation of species‐specific traits related to specialization, mobility and thermophily. Using linear regression models, variables are analysed in relation to site‐specific urbanization values quantified at seven scales (50–3,200 m radii). At best‐fitting scales, we test for taxonomic homogenization. Results: With increasing urbanization, abundance, species richness and Shannon diversity severely declined, with butterfly and macro‐moth declines due to local‐ versus landscape‐scale urbanization (200 vs. 800–3,200 m radii, respectively). While taxonomic homogenization was absent for butterflies, urban macro‐moth communities displayed higher nestedness than non‐urban communities. Overall, communities showed mean shifts towards generalist, mobile and thermophilous species, displaying trait convergence too. These functional trait models consistently fit best with urbanization quantified at local scales (100–200 m radii) for butterfly communities, and at local to wider landscape scales (200–800 m radii) for macro‐moth communities. Main conclusions: Urban communities display functional homogenization that follows urbanization at scales linked to taxon‐specific mobility. Light pollution may explain why homogenization was more pronounced for the nocturnal taxon. We discuss that urbanization is likely to impact flying insect communities across the globe, but also that impacts on their ecosystem functions and services could be mitigated via multi‐scale implementation of urban green infrastructure. [ABSTRACT FROM AUTHOR]

Abstract: Urbanization involves a cocktail of human‐induced rapid environmental changes and is forecasted to gain further importance. Urban‐heat‐island effects result in increased metabolic costs expected to drive shifts towards smaller body sizes. However, urban environments are also characterized by strong habitat fragmentation, often selecting for dispersal phenotypes. Here, we investigate to what extent, and at which spatial scale(s), urbanization drives body size shifts in macro‐moths—an insect group characterized by positive size‐dispersal links—at both the community and intraspecific level. Using light and bait trapping as part of a replicated, spatially nested sampling design, we show that despite the observed urban warming of their woodland habitat, macro‐moth communities display considerable increases in community‐weighted mean body size because of stronger filtering against small species along urbanization gradients. Urbanization drives intraspecific shifts towards increased body size too, at least for a third of species analysed. These results indicate that urbanization drives shifts towards larger, and hence, more mobile species and individuals in order to mitigate low connectivity of ecological resources in urban settings. Macro‐moths are a key group within terrestrial ecosystems, and since body size is central to species interactions, such urbanization‐driven phenotypic change may impact urban ecosystem functioning, especially in terms of nocturnal pollination and food web dynamics. Although we show that urbanization's size‐biased filtering happens simultaneously and coherently at both the inter‐ and intraspecific level, we demonstrate that the impact at the community level is most pronounced at the 800 m radius scale, whereas species‐specific size increases happen at local and landscape scales (50–3,200 m radius), depending on the species. Hence, measures—such as creating and improving urban green infrastructure—to mitigate the effects of urbanization on body size will have to be implemented at multiple spatial scales in order to be most effective. [ABSTRACT FROM AUTHOR]

Butterflies are often considered as opportunistic nectar consumers that visit a range of flower species. The degree of specialisation in foraging behaviour and flower choice may, however, vary considerably at the inter-specific level, from highly specialised to generalist species. In generalist nectar use, there can be intra-specific variation in the availability and use of floral resources (diversity and abundance) among different populations. Knowing the preferences of nectar-feeding butterflies can increase the understanding of ecological relationships and resource use and help in developing better strategies for butterfly conservation., By means of behavioural tracking, we identified foraging patterns of Maniola jurtina butterflies in nectar-rich and nectar-poor grasslands. For both males and females, we showed significant preference for the brown knapweed Centaurea jacea and thistles ( Cirsium sp.) in nectar-rich, extensively managed grasslands. In the absence of these preferred species, as is typically the case in nectar-poor intensively managed sites, M. jurtina nectared on Trifolium pratense and Leucanthemum vulgare. Flower visits were on average shorter on T. pratense compared to C. jacea. These observational results were confirmed by a field experiment in which a wild flower nectar array with C. jacea and T. pratense was introduced., In extensively managed grasslands, foraging bouts were generally confined to patches of flowering plants and did not involve long flights between flower visits. In intensively managed meadows, butterflies performed longer flights, and ignored more flowers between two consecutive visits. Despite the variety of flower species visited, M. jurtina showed a significant preference for a few nectar sources in a context-dependent way. [ABSTRACT FROM AUTHOR]

Climate alteration is one of the most cited ecological consequences of urbanization. However, the magnitude of this impact is likely to vary with spatial scale. We investigated how this alteration affects the biological fitness of insects, which are especially sensitive to ambient conditions and well-suited organisms to study urbanization-related changes in phenotypic traits. We monitored temperature and relative air humidity in wooded sites characterized by different levels of urbanization in the surroundings. Using a split-brood design experiment, we investigated the effect of urbanization at the local (i.e., 200 × 200 m) and landscape (i.e., 3 × 3 km) scale on two key traits of biological fitness in two closely related butterfly species that differ in thermal sensitivity. In line with the Urban Heat Island concept, urbanization led to a 1°C increase in daytime temperature and an 8% decrease in daytime relative humidity at the local scale. The thermophilous species Lasiommata megera responded at the local scale: larval survival increased twofold in urban compared to rural sites. Urbanized sites tended to produce bigger adults, although this was the case for males only. In the woodland species Pararge aegeria, which has recently expanded its ecological niche, we did not observe such a response, neither at the local, nor at the landscape scale. These results demonstrate interspecific differences in urbanization-related phenotypic plasticity and larval survival. We discuss larval pre-adaptations in species of different ecological profiles to urban conditions. Our results also highlight the significance of considering fine-grained spatial scales in urban ecology. [ABSTRACT FROM AUTHOR]

ABSTRACT Given the veterinary and public health impact of vector-borne diseases, there is a clear need to assess the suitability of landscapes for the emergence and spread of these diseases. Current approaches for predicting disease risks neglect key features of the landscape as components of the functional habitat of vectors or hosts, and hence of the pathogen. Empirical-statistical methods do not explicitly incorporate biological mechanisms, whereas current mechanistic models are rarely spatially explicit; both methods ignore the way animals use the landscape (i.e. movement ecology). We argue that applying a functional concept for habitat, i.e. the resource-based habitat concept ( RBHC), can solve these issues. The RBHC offers a framework to identify systematically the different ecological resources that are necessary for the completion of the transmission cycle and to relate these resources to (combinations of) landscape features and other environmental factors. The potential of the RBHC as a framework for identifying suitable habitats for vector-borne pathogens is explored and illustrated with the case of bluetongue virus, a midge-transmitted virus affecting ruminants. The concept facilitates the study of functional habitats of the interacting species (vectors as well as hosts) and provides new insight into spatial and temporal variation in transmission opportunities and exposure that ultimately determine disease risks. It may help to identify knowledge gaps and control options arising from changes in the spatial configuration of key resources across the landscape. The RBHC framework may act as a bridge between existing mechanistic and statistical modelling approaches. [ABSTRACT FROM AUTHOR]

Recent anthropogenic eutrophication has meant that host plants of nettle-feeding insects became quasi-omnipresent in fertile regions of Western Europe. However, host plant resource quality - in terms of microclimate and nutritional value - may vary considerably between the 'original' forest habitat and 'recent' agricultural habitat. Here, we compared development in both environmental settings using a split-brood design, so as to explore to what extent larval survival and adult morphology in the nettle-feeding butterfly Aglais urticae are influenced by the anthropogenic environment. Nettles along field margins had higher C/N ratios and provided warmer microclimates to larvae. Larvae developed 20% faster and tended to improve their survival rates, on the agricultural land compared to woodland. Our split-brood approach indicated plastic responses within families, but also family effects in the phenotypic responses. Adult males and females had darker wing pigmentation in the drier and warmer agricultural environment, which contrasts with the thermal melanism hypothesis. Developmental plasticity in response to this microclimatically different and more variable habitat was associated with a broader phenotypic parameter space for the species. Both habitat expansion and developmental plasticity are likely contributors to the ecological and evolutionary success of these nettle-feeding insects in anthropogenic environments under high nitrogen load. [ABSTRACT FROM AUTHOR]

Climate warming affects the rate and timing of the development in ectothermic organisms. Short-living, ectothermic organisms (including many insects) showing thermal plasticity in life-cycle regulation could, for example, increase the number of generations per year under warmer conditions. However, changed phenology may challenge the way organisms in temperate climates deal with the available thermal time window at the end of summer. Although adaptive plasticity is widely assumed in multivoltine organisms, rapid environmental change could distort the quality of information given by environmental cues that organisms use to make developmental decisions. Developmental traps are scenarios in which rapid environmental change triggers organisms to pursue maladaptive developmental pathways. This occurs because organisms must rely upon current environmental cues to predict future environmental conditions and corresponds to a novel case of ecological or evolutionary traps. Examples of introduced, invasive species are congruent with this hypothesis. Based on preliminary experiments, we argue that the dramatic declines of the wall brown Lasiommata megera in northwestern Europe may be an example of a developmental trap. This formerly widespread, bivoltine (or even multivoltine) butterfly has become a conundrum to conservationist biologists. A split-brood field experiment with L. megera indeed suggests issues with life-cycle regulation decisions at the end of summer. In areas where the species went extinct recently, 100% of the individuals developed directly into a third generation without larval diapause, whereas only 42.5% did so in the areas where the species still occurs. Under unfavourable autumn conditions, the attempted third generation will result in high mortality and eventually a lost or 'suicidal' third generation in this insect with non-overlapping, discrete generations. We discuss the idea of a developmental trap within an integrated framework for assessing the vulnerability of species to climate change. [ABSTRACT FROM AUTHOR]

Aim Species distribution models often assume a changing climate (dynamic climate variables) but unchanged land use (static land use variables) to estimate future species distribution shifts. However, scenarios of projected land use change are available to calculate dynamic land use variables. Surprisingly, the importance of using dynamic instead of static land use variables when projecting potential future species distributions under climate change remains largely unexplored. We tested whether the joint inclusion of land use and climate change scenarios altered the projection of future species distribution compared with the classical approach assuming unchanged land use. Location Europe Methods We used land use and climate change scenarios to estimate the future distribution of a butterfly species ( Lycaena dispar) according to different perspectives of projected environmental change: (1) land use change (dynamic land use and static climate variables), (2) climate change (static land use and dynamic climate variables) and (3) global change (dynamic land use and climate variables). As the importance of land use variables is known to depend on the spatial resolution of the models, we built them across a range of resolutions (50 km, 10 km and 5 km) to examine the resolution-dependent relevance of using dynamic instead of static variables. Results For each resolution, the projected distribution changes were unaltered when using dynamic instead of static land use variables in the models. It was mainly due to the low thematic resolution of the land use change scenarios that include only few dynamic variables. Main conclusions Even at fine spatial resolution (5 km), the available land use change scenarios poorly represent habitat suitability for the species. Hence, they may be of limited support to estimate future species distributions. Instead of supporting the assumption of unchanged future land use, our results plea for an improvement of the thematic resolution of land use change scenarios. [ABSTRACT FROM AUTHOR]

Insect flight is a highly energy demanding type of locomotion. In butterflies, males may locate females by different behavioural tactics. The tactics correspond to different flight types that, in turn, are assumed to reflect different energetic costs. Costs need to be considered to fully understand the pay-offs of co-existing alternative tactics relative to the environmental context and the phenotypes of the individuals. We addressed the issue in the speckled wood Pararge aegeria, in which males either adopt a territorial wait-and-fight tactic (i.e. territorial perching) in a sunlit patch on the forest floor, or a fly-and-search tactic to locate females in a wider area of the forest (i.e. patrolling). Perching corresponds to high frequency of take-off flights and aerial combats with high levels of manoeuvrability and is assumed to be energetically more costly than longer, continuous flights at lower speed in patrollers. We tested the effect of different flight activity levels and of the behavioural tactics on lipid reserves and lipid use in males by laboratory and outdoor cage experiments. Low-activity males that had access to honey water were capable of synthesizing lipids; their lipid reserves increased with age. The effect disappeared in males that actively flew in the outdoor cages. Lipid reserves decreased significantly faster in territorial perching males compared to non-perching males, but resting metabolic rate did not differ between the alternative behavioural tactics. Territorial perching males had larger flight muscle ratio (i.e. thorax/body mass) than non-perching males. We discuss the evidence of the physiological costs of perching relative to the co-existence of perching and patrolling tactics. [ABSTRACT FROM AUTHOR]

1. Understanding the causes and consequences of dispersal remains a central topic in ecology and evolution. However, a mismatch exists between our empirical understanding of the complexity of dispersal and our representation of dispersal in models. While the empirical literature is replete with examples of condition dependence at the emigration, movement and settlement phases, models rarely incorporate realism or complexity to this degree. Nor do models often include the different costs associated with dispersal, which can themselves be linked to one or more of the three key phases. 2. Here, we propose that by explicitly accounting for emigration, movement and settlement (and the multiple costs associated with each) we can substantially improve our understanding of both the dispersal process itself and how dispersal traits trade off against other life-history characteristics. We explore some of these issues conceptually, before presenting illustrative results gained from a flexible individual-based model which incorporates considerable dispersal complexity. 3. These results emphasise the nonlinear interplay between the different dispersal stages. For example, we find that investment in movement ability (at a cost to fecundity) depends upon the propensity to emigrate (and vice versa). However, owing to selection acting at the metapopulation level as well as at the individual level, the relationship between the two is not straightforward. Importantly, the shape of the trade-off between movement ability and reproductive potential can strongly influence the joint evolution of dispersal parameters controlling the degree of investment in safer movement, the probability of emigration and the straightness of movement. 4. Our results highlight that the joint evolution of dispersal characteristics can have major implications for spatial population dynamics and we argue that, in addition to increasing our fundamental biological understanding, a new generation of dispersal modelling, which exploits recent empirical advances, can substantially improve our ability to predict and manage the response of species to environmental change. [ABSTRACT FROM AUTHOR]

Dispersal costs can be classified into energetic, time, risk and opportunity costs and may be levied directly or deferred during departure, transfer and settlement. They may equally be incurred during life stages before the actual dispersal event through investments in special morphologies. Because costs will eventually determine the performance of dispersing individuals and the evolution of dispersal, we here provide an extensive review on the different cost types that occur during dispersal in a wide array of organisms, ranging from micro-organisms to plants, invertebrates and vertebrates. In general, costs of transfer have been more widely documented in actively dispersing organisms, in contrast to a greater focus on costs during departure and settlement in plants and animals with a passive transfer phase. Costs related to the development of specific dispersal attributes appear to be much more prominent than previously accepted. Because costs induce trade-offs, they give rise to covariation between dispersal and other life-history traits at different scales of organismal organisation. The consequences of ( i) the presence and magnitude of different costs during different phases of the dispersal process, and ( ii) their internal organisation through covariation with other life-history traits, are synthesised with respect to potential consequences for species conservation and the need for development of a new generation of spatial simulation models. [ABSTRACT FROM AUTHOR]

There is a growing recognition for the significance of evolutionary thinking in ecology and conservation biology. However, ecology and conservation studies often work with species-specific, fixed traits that ignore intraspecific variation. The way the habitat of a species is considered is an example of typological thinking biased by human perception. Structural habitat units (e.g., land cover types) as perceived by humans may not represent functional habitat units for other organisms. Human activity may also interfere with the environmental information used by organisms. Therefore, the Umwelt-concept from ethology needs to be integrated in the way we think about habitat and habitat selection. It states that different organisms live in different perceptual worlds dealing with specific subsamples of the environment as a result of their evolutionary and developmental history. The resource-based habitat concept is a functional habitat model based on resource distributions (consumables and conditions) and individual movements. This behavioural approach takes into account aspects that relate to the perceptual world of organisms. This approach may offer new opportunities for conservation and may help avoid failures with habitat restoration. Perceptual ability may be subject to adaptive change, but it may also constrain organisms from showing adaptive behaviours in rapidly changing environments. [ABSTRACT FROM AUTHOR]

With global climate change, rainfall is becoming more variable. Predicting the responses of species to changing rainfall levels is difficult because, for example in herbivorous species, these effects may be mediated indirectly through changes in host plant quality. Furthermore, species responses may result from a simultaneous interaction between rainfall levels and other environmental variables such as anthropogenic land use or habitat quality. In this eco-evolutionary study, we examined how male and female Pararge aegeria (L.) from woodland and agricultural landscape populations were affected by the development on drought-stressed host plants. Compared with individuals from woodland landscapes, when reared on drought-stressed plants agricultural individuals had longer development times, reduced survival rates and lower adult body masses. Across both landscape types, growth on drought-stressed plants resulted in males and females with low forewing aspect ratios and in females with lower wing loading and reduced fecundity. Development on drought-stressed plants also had a landscape-specific effect on reproductive output; agricultural females laid eggs that had a significantly lower hatching success. Overall, our results highlight several potential mechanisms by which low water availability, via changes in host plant quality, may differentially influence P. aegeria populations relative to landscape structure. [ABSTRACT FROM AUTHOR]

Ecology Letters (2011) 14: 74-86 Abstract As dispersal plays a key role in gene flow among populations, its evolutionary dynamics under environmental changes is particularly important. The inter-dependency of dispersal with other life history traits may constrain dispersal evolution, and lead to the indirect selection of other traits as a by-product of this inter-dependency. Identifying the dispersal's relationships to other life-history traits will help to better understand the evolutionary dynamics of dispersal, and the consequences for species persistence and ecosystem functioning under global changes. Dispersal may be linked to other life-history traits as their respective evolutionary dynamics may be inter-dependent, or, because they are mechanistically related to each other. We identify traits that are predicted to co-vary with dispersal, and investigated the correlations that may constrain dispersal using published information on butterflies. Our quantitative analysis revealed that (1) dispersal directly correlated with demographic traits, mostly fecundity, whereas phylogenetic relationships among species had a negligible influence on this pattern, (2) gene flow and individual movements are correlated with ecological specialisation and body size, respectively and (3) routine movements only affected short-distance dispersal. Together, these results provide important insights into evolutionary dynamics under global environmental changes, and are directly applicable to biodiversity conservation. [ABSTRACT FROM AUTHOR]

Bergman and converse Bergman rules, amongst others, describe latitudinal variation in size of organisms, including flying ectotherms like butterflies. However, geographic clines in morphological traits of functional significance for flight performance and thermoregulation may also exist, although they have received less attention within a biogeographical context. Variation in flight-related morphology has often been studied relative to landscape structure. However, the extent to which landscape effects interact with latitudinal clines of phenotypic variation has rarely been tested. Here we address the effect of latitude, landscape type and the interaction effect on body size and flight-related morphology in the speckled wood butterfly Pararge aegeria. Male adult butterflies were collected from two replicate populations in each agricultural and woodland landscape types along a 700 km cline in six latitudinal zones. Overall size, adult body mass and wing area increased with latitude in line with Bergmann's rule. Forewing length, however, decreased with latitude. As predicted from thermoregulatory needs in ectotherms, the basal wing part was darker to the north. Latitudinal trends for flight-related morphological traits were opposite to predictions about flight endurance under cooler conditions that were observed in some non-lepidopteran insects, i.e. wing loading increased and wing aspect ratio decreased with latitude. Opposite trends can, however, be explained by other aspects of butterfly flight performance (i.e. mate-location behaviour). As predicted from differences in environmental buffering in woodland landscapes along the latitudinal gradient, significant landscape×latitude interaction effects indicated stronger latitudinal clines and stronger phenotypic variation for size and flight morphology in the agricultural landscape compared to the woodland landscape. In agreement with significant interaction effects, morphological differentiation increased with latitude and was higher between population pairs of agricultural landscape than between population pairs of woodland landscape. These results demonstrate that landscape, latitude and their interaction contribute to the understanding of the complex geographic variation in P. aegeria adult phenotypes across Europe. [ABSTRACT FROM AUTHOR]

In insects, spermatophore production represents a non-trivial cost to a male. Non-virgin males have been shown to produce small spermatophores at subsequent matings. Particularly in monandrous species, it may be an issue to receive a sufficiently large spermatophore at the first and typically only mating. Females of the monandrous Speckled wood butterfly Pararge aegeria (L.) produce fewer offspring after mating with a non-virgin male. After mating, females spend all their active time selecting oviposition sites and typically ignore other males. Here, we show that females did not discriminate between a virgin male and a recently mated male in our laboratory experiments. We demonstrate that the number of eupyrene sperm bundles relative to spermatophore mass differed with subsequent male matings. Males transferred a significantly smaller spermatophore after the first copulation, but the spermatophore mass did not decrease further with subsequent matings. However, the number of eupyrene sperm bundles decreased linearly. Therefore, there was proportionally more eupyrene sperm in the male's second spermatophore compared with the first and the later spermatophores. Such a pattern has been shown in polyandrous species. Hence, it suggests that differences in sperm allocation strategy between polyandrous and monandrous butterflies may be quantitative rather than qualitative. There was also a tendency for females that had mated with a recently mated male to have higher propensity to remate than did females that had mated with a virgin male. We discuss the results relative to the mating system in P. aegeria, including female remating opportunities in the field and male mate-locating behaviour. [ABSTRACT FROM AUTHOR]

Butterfly distribution and abundance is known to be influenced by temperature and rainfall. What is not clear, however, is how life history and flight morphological traits are affected by changes in local weather conditions. During the period 1989-1999, we explored the effects of ambient temperature and rainfall during larval development on adult phenotypic traits (body mass, forewing loading, forewing surface area and forewing length) in a Swedish population of the speckled wood butterfly Pararge aegeria. As different seasonal cohorts correspond to different developmental pathways (larval hibernating, pupal hibernating and directly developing), we analysed these morphological time series relative to developmental pathway. Phenotypic variation in response to the temperature and rainfall levels experienced during larval development differed in both magnitude and direction depending on the developmental pathway, and hence seasonal cohort, examined (i.e. there was a pathway-specific response). We suggest that through its developmental flexibility P. aegeria may be able to adjust to variation in weather conditions over time. Other less flexible species, however, may not be so fortunately buffered. To truly estimate the impact of climate change on biodiversity more fine-scale, local studies are required that examine the mechanisms underlying the response of species to climate change. [ABSTRACT FROM AUTHOR]

1. Insects locate mobile resources like prey items or mates using either sit-and-wait ('perching') or active ('patrolling') searching strategies. The sit-and-wait strategy can be accompanied by defending and monopolising a site through territorial behaviour. 2. The present study focuses on the territorial perching behaviour in males of the speckled wood butterfly ( Pararge aegeria L.). Recent studies suggested that the selection of territories (i.e. sunlit patches on the forest floor) is driven by structural characteristics of the site that affect male visual detection. However, given that adult butterflies are heliothermic organisms and that forests provide a diverse array of light environments, it seems likely that thermal aspects may also be used for territory selection. 3. We tested whether used and unused sunlit patches differed in thermal profile under field conditions in a Belgian woodland. We also used dummy butterflies to quantify variation in operative thoracic temperature and to calculate heating rates within (i.e. different vegetation structures) and between patches. 4. Sunlit patches occupied by a territorial male were larger, and were more frequently characterised by low vegetation structures compared with empty sunlit patches. It took longer to reach optimal thorax temperature (starting from a fixed suboptimal body temperature) in small patches compared with large patches. 5. We suggest that aspects of visual detection need to be combined with thermal aspects to fully understand territory selection in the speckled wood butterfly, as synergetic and/or trade-off effects of ambient temperature, solar radiation, and canopy/vegetation structure may be involved. [ABSTRACT FROM AUTHOR]

The European map butterfly ( Araschnia levana L.) is a striking example of seasonal plasticity. Individuals of the spring generation are reddish with a fritillary-like colour pattern, whereas the summer generation is black with a white dorsal stripe. Proximate factors explaining the development of the forms are well known, but ultimate explanations have not been tested experimentally yet. The reddish spring form is assumed to have a warning coloration, as found in other nymphalid butterflies that are unpalatable ( Aglais urticae). We tested for differential predation by a visually hunting predator ( Parus major) in a laboratory experiment using artificial butterflies designed to represent the spring and summer form. Birds were released individually in a flight cage where the alternative forms were presented. Summer forms were more frequently attacked than spring forms, which may point to some aversion against the reddish spring form. But there was also a strong effect of the interaction between seasonal form and type of substrate. Spring forms were much better protected from attacks on the brown substrate of dead leaves compared to the green substrate of nettle leaves. On the latter substrate, latency times before attacking spring forms were on average 2.5 times longer than for summer forms. Experiments with artificial butterflies simplify complex predator-prey interactions because they exclude potential taste or odour effects and they also exclude behavioural responses and interactions of the butterfly. However, our results based on static visual signals provide a promising first step to test the functional significance of this striking seasonal polyphenism. [ABSTRACT FROM AUTHOR]

In contrast to several organisms that have already shown range shifts to the north as a response to climate change, southern populations of relict species are trapped in isolated altitudinal habitats. Therefore, there is a growing interest to better understand their habitat use, with particular attention to the thermal aspects and associated significance for their habitat management. We address this issue by a study of larval habitat use relative to vegetation structure and microclimate in a glacial relict butterfly of peat bog ecosystems, using a functional, resource-based habitat approach. We analysed caterpillar presence and density relative to vegetation composition (reflecting gradients of humidity, temperature, and natural succession of the peat bog) and to the availability and quality of thermal refuges for caterpillars (i.e., structures provided by Sphagnum hummocks). We also tested caterpillar survival rates under different temperature and humidity treatments. We found that (1) Boloria aquilonaris was a specialist butterfly of early successional stages with very humid zones of peat bog, (2) the lack of Sphagnum hummocks reduced larval habitat suitability, and hence the population density, and (3) a reduction of the thermal buffering ability of Sphagnum hummocks was observed in less humid, degraded parts, or late-successional stages of peat bog. A larval rearing experiment showed a significant impact of temperature on caterpillar survival; survival being higher at lower temperature. Our field and laboratory results support the idea that the thermal environment exploited by caterpillars should be considered as a functional resource and included in a population-specific habitat definition. Appropriate management of the peat bog habitat of this glacial relict species should not exclusively focus on the larval and adult feeding resources, but also on the quality of thermal refuges provided by Sphagnum hummocks in humid zones of the peat bog, especially in the current critical context of climate warming. [ABSTRACT FROM AUTHOR]

As a result of increased habitat fragmentation in anthropogenic landscapes, flying insects may be required to travel over larger distances in search of resources such as suitable host plants for oviposition. The oögenesis–flight syndrome hypothesis predicts that physiological constraints caused by an overlap in the resources used by thoracic muscles during flight and during oögenesis (e.g. carbohydrates, lipids and water) result in a resource trade-off, with any resources used during flight no longer available for reproduction. Increased flight costs could therefore potentially result in a decrease in maternal provisioning of eggs. In the present study, the speckled wood butterfly Pararge aegeria (L.) is used to investigate whether increased flight during oviposition results in changes in maternal investment in eggs and whether this contributes to variation in the development of offspring in subsequent life stages. Forcing females to fly during oviposition directly influences egg size and embryonic development time, and indirectly influences (through changes in egg size) egg hatching success and larval development time. These effects are mediated through ‘selfish maternal effects’, with mothers forced to fly maximizing their fecundity at the expense of investment to individual egg size. The present study demonstrates that a change in maternal provisioning as a result of increased flight during oviposition has the potential to exert nongenetic cross-generational fitness effects in P. aegeria. This could have important consequences for population dynamics, particularly in fragmented anthropogenic landscapes. [ABSTRACT FROM AUTHOR]

Analyses of species' population losses typically show a dichotomy between strongly affected, rare, and localized species and apparently unaffected, common, and widespread species. We analyzed 16 years (1992–2007) of butterfly transect count data from The Netherlands in a reevaluation of the trends of common, widespread species. Fifty-five percent (11 of 20 species) of these species suffered severe declines in distribution and abundance. Overall, cumulative butterfly abundance declined by around 30%. Some of the species in decline used to be omnipresent in gardens and parks, and 2 of the species were previously considered agricultural pests. Based on their declines over the last 16 years, 2 of the 20 species (Lasiommata megera and Gonepteryx rhamni ) reached endangered status in The Netherlands under the IUCN (International Union for Conservation of Nature) population-decline criterion, and 2 species (Inachis io and Thymelicus lineola ) met vulnerable criterion. Butterflies in farmland, urban, and particularly woodland areas showed the largest decline in species abundance. The abundance of species associated with vegetation types found mainly in nature reserves (dunes, heathland, and, to a lesser extent, seminatural grassland) increased or remained stable. The decline of widespread species requires additional conservation strategies in the wider landscape. [ABSTRACT FROM AUTHOR]

The precise knowledge of ecological resources and conditions required by species threatened by rapidly changing environmental conditions is of prime importance for conservation biology. Transferability of this knowledge between species with similar ecological requirements is often assumed, but rarely tested. This is especially the case for glacial relict populations confined to climate-habitat traps from where they cannot move to rejoin areas with suitable environmental conditions. Using two glacial relict butterflies as model organisms, we first quantitatively define larval and adult resource-based habitat use of each species. Secondly, we test the transferability of ecological profiles (both habitat and ecological niche) between these two species that share both the same biotope and the same host plant. Our results show that both species have markedly different ecological requirements relating to differences in life history and behavioural traits (i.e. egg-laying strategies and mate-locating behaviour). Although the two species share many ecological features, they use different functional habitats within our study site. The high degree of interspecific niche overlap should indicate a high interspecific competition. However, we argue that their co-existence can be explained by the non-limiting abundance of some resources (e.g. host plants), by the partial separation in time of adult flight periods and by the territorial behaviour of one of the species. We discuss the following general messages: (1) functional habitat of a (threatened) species should be defined in a spatial context corresponding to individual station keeping, and (2) quick diagnosis based on similar ecological requirements may be misleading for the design of reliable conservation and restoration strategies. Detailed mechanistic and quantitative ecological understanding of resource-use and environmental tolerances across an organism's life cycle is essential for effective conservation in changing environments, like for glacial relict species. [ABSTRACT FROM AUTHOR]

1. Adaptive plasticity in flight morphology can be of great importance for organisms, in order to deal with changing environments. When different demands are imposed to this morphology, different responses to environmental changes can be expected. 2. The aim of this study is to examine whether males and females of Pararge aegeria, which show different flight behaviours, respond differently to larval food stress. 3. In a food-stress experiment, larvae of 35 families were reared on host plants subjected to a drought-stress treatment with three groups: a control group, a low-stress group and a high-stress group. 4. Individuals from stress treatments significantly differed in wing morphology; they had lower wing loadings, and stressed females tended to have more pointed wings than females of the control group. 5. The difference in phenotypic response to food stress between both sexes may indicate that males and females benefit from different changes in morphology. In females, an increase in dispersal capacity may entail fitness benefits, whereas male morphology is mainly shaped by mate-location strategy. [ABSTRACT FROM AUTHOR]

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In evolutionary time, varying environments may lead to different morphs as a result of genetic adaptation and divergence or phenotypic plasticity. Landscapes that differ in the extent of habitat fragmentation may provide different selection regimes for dispersal, but also for other ecological functions. Several studies on flying insects have shown differences in flight morphology between landscapes, but whether such differences result from plastic responses have rarely been tested. We did a reciprocal transplant experiment with offspring of speckled wood butterfly females ( Pararge aegeria) from three types of landscape differing in fragmentation: woodland landscape, landscape with woodland fragments and agricultural landscape with only hedgerows. Young caterpillars were allowed to grow individually on potted host grasses in small enclosures under the three landscape conditions (split-brood design). Mortality in caterpillars was much higher in agricultural landscape compared to the other landscapes. Additive to the effect of landscape of development, landscape of origin also affected mortality rate in a similar way. Flight morphology of the adults resulting from the experiment differed significantly with landscape. Independent of the landscape of origin, males and females that developed in agricultural landscape were the heaviest and had the greatest wing loadings. Females that developed in agricultural landscape had higher relative thorax mass (i.e. greater flight muscle allocation) in line with adaptive predictions on altered dispersal behaviour with type of landscape. In males, relative thorax mass did not respond significantly relative to landscape of development, but males originating from landscape with woodland fragments allocated more into their thorax compared to males from the other types. We found significant G×E interactions for total dry mass and wing loading. Our results suggest the existence of phenotypic plasticity in butterfly flight morphology associated with landscape structure. [ABSTRACT FROM AUTHOR]

Focuses on the concept of habitat. Description of the Venn diagram; Applicability of the metapopulation models; Complexity of resource distribution in spatial population models of butterflies.

1. Larvae from eggs of fifteen wild-caught speckled wood females were reared individually under common conditions (LD 18:6 h and 17 °C) in the laboratory. 2. Pupal colour (green or brown) and the following adult morphological variables that are known or assumed to be related to behavioural variation (thermoregulation, flight, crypsis) were studied: size, relative thorax mass, area of yellow patches on the dorsal forewing, size of submarginal eyespots on the dorsal hindwing, colour of the dorsal thorax, dorsal basal wing, and dorsal distal wing. 3. The results of the breeding experiment indicate significant differences in adult morphological traits among families, sexes, and pupal colour types. 4. All adult morphological variables (except spot size and thorax colouration) differed significantly among families, suggesting genetic variation underlying the phenotypic variation. Heritabilities for these features were intermediate (0.38) to high (> 1). 5. Apart from known aspects (e.g. size), novel aspects of the sexual dimorphism were found: females had paler thoraxes than males, which relates to higher abundance of fur on the thorax and hence to thermoregulatory differences. 6. Green pupae produced larger individuals with a larger relative thorax mass than brown pupae. Green pupae produced adults with a paler basal wing colour in females, but not in males. These relationships are novel and suggest a trade-off between juvenile and adult investment. [ABSTRACT FROM AUTHOR]

The habitat is the basic unit for developments in life history, population dynamics, landscape ecology and conservation of organisms. It is frequently treated as a particulate, invariant and homogeneous entity (a patch). Here we examine the implications of using this concept of habitat in butterfly biology. In doing so, we suggest the alternative approach of applying a functional resource-based concept of habitat. This recognises the fundamental requirements of organisms, consumables and utilities, the latter describing suitable environmental conditions as well as essential substrates. We argue that a resource-based concept is critical for butterfly conservation and call for the development of a resource database on butterfly biology . [ABSTRACT FROM AUTHOR]