NICOLAS, Jean-Hervé, o.p., Contemplation et vie contemplative

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

Development on drought-stressed host plants affects life history, flight morphology and reproductive output relative to landscape structure

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

Quantitative analysis of changes in movement behaviour within and outside habitat in a specialist butterfly

BACKGROUND: Dispersal between habitat patches is a key process in the functioning of (meta)populations. As distance between suitable habitats increases, the ongoing process of habitat fragmentation is expected to generate strong selection pressures on movement behaviour. This leads to an increase or decrease of dispersal according to its cost relative to landscape structure. To limit the cost of dispersal in an increasingly hostile matrix, we predict that organisms would adopt special dispersal behaviour between habitats, which are different from movements associated with resource searching in suitable habitats. RESULTS: Here we quantified the movement behaviour of the bog fritillary butterfly (Proclossiana eunomia) by (1) assessing perceptual range, the distance to which the habitat can be perceived, and (2) tracking and parameterizing movement behaviour within and outside habitat (parameters were move length and turning angles distributions). Results are three-fold. (1) Perceptual range was < 30 m. (2) Movements were significantly straighter in the matrix than within the habitat. (3) Correlated random walk adequately described movement behaviour for 70% of the observed movement paths within habitat and in the matrix. CONCLUSION: The perceptual range being lower than the distance between habitat patches in the study area, P. eunomia likely perceives these habitat networks as fragmented, and must locate suitable habitats while dispersing across the landscape matrix. Such a constraint means that dispersal entails costs, and that selection pressure should favour behaviours that limit these costs. Indeed, our finding that dispersal movements in the matrix are straighter than resource searching movements within habitat supports the prediction of simulation studies that adopting straight movements for dispersal reduces its costs in fragmented landscapes. Our results support the mounting evidence that dispersal in fragmented landscapes evolved towards the use of specific movement behaviour, different from explorative searching movements within habitat

Dissociative experiences in the general population in the Netherlands and Belgium: a study with the Dissociative Questionaire (DIS-Q)

p. 180-184This article describes the results of the first European study on the prevalence of dissociative experiences in the general population of Belgium (Flanders) and the Netherlands. Dissociative experiences were assessed with a new self-reporting dissociation questionnaire (DIS-Q). The DIS-Q has been administered to a representative sample of the Dutch and Flemish population (N=374). The results show that dissociative experiences are quite common in the general population, and that their frequency is declining with age. About 3 percent of the population (the majority men) reports serious dissociative phenomena, and 1 percent shows scores as high as patients with multiple personality disorder. These findings suggest that dissociative disorders are seriously under-diagnosed by mental health professionals

Variation in life history and flight morphological traits in Speckled Wood (Pararge aegeria) butterflies infected with a baculovirus.

Sub-lethal impacts are known to affect the insect-host relationship and have an important role in describing host dynamics. The impact of sub-lethal infections of pathogens on life history traits of affected hosts has been understudied in natural or semi-natural systems. The Speckled Wood (Pararge aegeria) is a satyrine butterfly that is common in temperate zones and has been extensively used as a model system for evolutionary ecology studies. It is known that the deployment of the immune system within this species, as with other invertebrates, is energetically costly and may result in trade-offs with fitness-related traits. In this study, we investigated the sub-lethal effect of exposure to Autographa californica multiple nucleopolyhedrovirus (AcMNPV) on life history and flight morphological traits of P. aegeria. Larvae were inoculated with increasing doses of AcMNPV and measurements made of life history and flight morphology traits. Generally, larvae exposed to virus took longer to develop to pupae and larval mass acquisition per day was significantly reduced in viral exposed larvae. However, viral exposed larvae were able to attain the same pupal mass and their duration as pupae was the same as controls. Forewing length, forewing aspect ratio, dry thorax mass and forewing loading were related to sex and bioassay differences but there was no evidence of any viral impact on these measures. Adult male butterflies had significantly less basal wing melanisation when exposed to virus compared to control males but there was no difference between females. Implications for population dynamics of P. aegeria are discussed

Flight-induced transgenerational maternal effects influence butterfly offspring performance during times of drought

Maternal condition can generate resource-related maternal effects through differential egg provisioning that can negatively affect offspring performance especially when offspring growth occurs in stressful or sub-optimal environments. Using the Speckled Wood butterfly, Pararge aegeria (L.) we tested the hypothesis that repeated periods of intensive flight during female oviposition affects egg provisioning and reduces offspring performance when larval development occurs under stressful conditions on drought stressed host plants. We investigated whether (after controlling for egg size) maternal age and flight treatment resulted in changes in egg provisioning and whether this contributed to variation in offspring traits across life stages. Age-related changes in maternal condition were found to generate resource-related maternal effects that influenced offspring traits across all life stages. Flight-induced changes in maternal egg provisioning were found to have direct consequences for offspring development in the egg and larval stages.. There were significant interactive effects between maternal age and flight on larval development and growth. Compared to offspring from forced flight mothers, offspring from control (no forced flight) mothers that hatched from eggs laid early in the oviposition period (i.e. by younger mothers) had shorter larval development times and heavier pupal masses, suggesting that offspring from mothers in relatively good condition may be able to buffer some of the costs associated with growth on drought stressed host plants. Our multi-factor study demonstrates the importance of considering the various, and often interacting, mechanisms by which maternal effects may influence offspring performance in stressful environments

Suitability and Transferability of the Resource-Based Habitat Concept: A Test With an Assemblage of Butterflies

A functional definition of the habitat-concept based on ecological resources incorporates three interconnected parameters: composition, configuration, and availability of the resources. The intersection of those parameters represents the functional habitat of a given population or species. Resource composition refers to the co-occurrence of the resources required by each individual to complete its life cycle. Resource configuration refers both to the way individual resources are spatially distributed within the habitat and the way all the resources are organized in the habitat space. Resource availability refers to the accessibility and procureability of resources. Variation in these variables is predicted to influence the demography of the population. To test the suitability of this definition and its transferability across landscapes, we first conducted a very detailed study on habitat and resource use of five butterfly species within a large nature reserve. Second, we conducted a larger-scale study, focusing on metapopulations of two species. We monitored demography for each species and tested whether its variation can be explained by (1) the vegetation type, (2) the vegetation composition or (3) the availability and configuration of the species-specific ecological resources. To confirm that resource availability and configuration reflect habitat quality, we also assessed their impacts on individual morphology. Whatever the investigated spatial scale, our results quantitatively demonstrate the overall better performance of the resource-based habitat approach compared to other most commonly used approaches. Our analysis allowed us to assess the relative importance of each ecological resource in terms of both their availability and organization relative to the species' abundance, demography and individual fitness measures. Resource availability did not play the predominant role in defining habitat quality as it was in most cases overruled by resource organization. Finally, we confirmed the between-population transferability of the habitat definition and quality estimates while adopting a resource-based habitat approach. Our study clearly demonstrates the suitability of the resource-based definition of the habitat. Therefore, we argue that this approach should be favored for species of conservation concern. Although most conclusions so far have emerged from butterfly studies, the resource-based definition of the habitat should also be ecologically relevant to many other organisms

Population Genetic Differences along a Latitudinal Cline between Original and Recently Colonized Habitat in a Butterfly

BACKGROUND: Past and current range or spatial expansions have important consequences on population genetic structure. Habitat-use expansion, i.e. changing habitat associations, may also influence genetic population parameters, but has been less studied. Here we examined the genetic population structure of a Palaeartic woodland butterfly Pararge aegeria (Nymphalidae) which has recently colonized agricultural landscapes in NW-Europe. Butterflies from woodland and agricultural landscapes differ in several phenotypic traits (including morphology, behavior and life history). We investigated whether phenotypic divergence is accompanied by genetic divergence between populations of different landscapes along a 700 km latitudinal gradient. METHODOLOGY/PRINCIPAL FINDINGS: Populations (23) along the latitudinal gradient in both landscape types were analyzed using microsatellite and allozyme markers. A general decrease in genetic diversity with latitude was detected, likely due to post-glacial colonization effects. Contrary to expectations, agricultural landscapes were not less diverse and no significant bottlenecks were detected. Nonetheless, a genetic signature of recent colonization is reflected in the absence of clinal genetic differentiation within the agricultural landscape, significantly lower gene flow between agricultural populations (3.494) than between woodland populations (4.183), and significantly higher genetic differentiation between agricultural (0.050) than woodland (0.034) pairwise comparisons, likely due to multiple founder events. Globally, the genetic data suggest multiple long distance dispersal/colonization events and subsequent high intra- and inter-landscape gene flow in this species. Phosphoglucomutase deviated from other enzymes and microsatellite markers, and hence may be under selection along the latitudinal gradient but not between landscape types. Phenotypic divergence was greater than genetic divergence, indicating directional selection on some flight morphology traits. MAIN CONCLUSIONS/SIGNIFICANCE: Clinal differentiation characterizes the population structure within the original woodland habitat. Genetic signatures of recent habitat expansion remain, notwithstanding high gene flow. After differentiation through drift was excluded, both latitude and landscape were significant factors inducing spatially variable phenotypic variation