Nature-Based Solutions in the EU: Innovating with nature to address social, economic and environmental challenges

Contemporary societies are facing a broad range of challenges, from pressures on human health and well-being to natural capital depletion, and the security of food, water and energy. These challenges are deeply intertwined with global processes, such as climate change and with local events such as natural disasters. The EU's research & innovation (R&I) policy is now seeking to address these challenges from a new perspective, with Nature-Based Solutions, and turn them into innovation opportunities that optimise the synergies between nature, society and the economy. Nature-Based Solutions can be an opportunity for innovation, and are here promoted by both policymakers and practitioners as a cost-effective way of creating a greener, more sustainable, and more competitive economy. Since 2013, the European Commission has devoted particular attention to Nature-Based Solutions through consultations and dialogues that sought to make the concept of these solutions more concrete and to define the concept's place within the spectrum of ecosystem-based approaches. In 2014, the Commission launched an expert group, which conducted further analysis, and made recommendations to help increase the use of Nature-Based Solutions and bring nature back into cities. In 2015, a survey was conducted on citizens' views and perceptions of 'Nature in Cities' to provide further insight for future work. Based on these elements and on results from running EU projects, the Commission has developed an R&I agenda for Nature-Based Solutions and has published targeted calls for proposals for large-scale demonstration projects in this field in 2016 and 2017. Additional R&I actions at EU level that promote systemic Nature-Based Solutions and their benefits to cities and territories are planned with the aim to improve the implementation capacity and evidence base for deploying Nature-Based Solutions and developing corresponding future markets. They are also expected to foster an interdisciplinary R&I and stakeholder community and the exchange of good practices in this field, as well as help shaping and implementing international R&I agendas on Nature-Based Solutions.

Conservation genetics of a threatened butterfly: comparison of allozymes, RAPDs and microsatellites

Background

Addressing genetic issues in the management of fragmented wild populations of threatened species is one of the most important challenges in conservation biology. Nowadays, a diverse array of molecular methods exists to assess genetic diversity and differentiation of wild populations such as allozymes, dominant markers and co-dominant markers. However it remains worthwhile i) to compare the genetic estimates obtained using those several markers in order to ii) test their relative utility, reliability and relevance and iii) the impact of these results for the design of species-specific conservation measures.

Results

Following the successful isolation of 15 microsatellites loci for the cranberry fritillary butterfly, Boloria aquilonaris, we analyzed the genetic diversity and structure of eight populations located in four different landscapes, at both the regional and the landscape scales. We confront results based on microsatellites to those obtained using allozymes and RAPDs on the same samples. Genetic population analyses using different molecular markers indicate that the B. aquilonaris populations are characterized by a weak genetic variation, likely due to low effective population size and low dispersal at the regional scale. This results in inbreeding in some populations, which may have detrimental consequences on their long term viability. However, gene flow within landscape is limited but not inexistent, with some long range movements resulting in low or no isolation by distance. Spatial structuring was detected among the most isolated populations.

Conclusions

The use of allozymes and RAPD are of very limited value to determine population structuring at small spatial (i.e. landscape) scales, microsatellites giving much higher estimate resolution. The use of RAPD data is also limited for evidencing inbreeding. However, coarse-grain spatial structure (i.e. regional scale), and gene flow estimates based on RAPD and microsatellites data gave congruent results. At a time with increasing development of new molecular methods and markers, dominant markers may still be worthwhile to consider in organisms for which no genomic information is available, and for which limited resources are available.

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.

Effects of individual and population parameters on reproductive success in three sexually deceptive orchid species

Reproductive success (RS) in orchids in general, and in non-rewarding species specifically, is extremely low. RS is pollinator and pollination limited in food deceptive orchids, but this has rarely been studied in sexually deceptive orchid species. Here, we tested the effects of several individual (plant height, inflorescence size, nearest neighbour distance and flower position) and population (patch geometry, population density and size) parameters on RS in three sexually deceptive Ophrys (Orchidaceae) species. Inter-specific differences were observed in RS of flowers situated in the upper versus the lower part of the inflorescence, likely due to species-specific pollinator behaviour. For all three species examined, RS increased with increasing plant height, inflorescence size and nearest neighbour distance. RS generally increased with decreasing population density and increasing patch elongation. Given these results, we postulate that pollinator availability, rather than pollinator learning, is the most limiting factor in successful reproduction for sexually deceptive orchids. Our results also suggest that olfactory 'display' (i.e. versus optical display), in terms of inflorescence size (and co-varying plant height), plays a key role in individual RS of sexually deceptive orchids. In this regard, several hypotheses are suggested and discussed.

Positive correlation between genetic diversity and fitness in a large, well-connected metapopulation

BACKGROUND

Theory predicts that lower dispersal, and associated gene flow, leads to decreased genetic diversity in small isolated populations, which generates adverse consequences for fitness, and subsequently for demography. Here we report for the first time this effect in a well-connected natural butterfly metapopulation with high population densities at the edge of its distribution range.

RESULTS

We demonstrate that: (1) lower genetic diversity was coupled to a sharp decrease in adult lifetime expectancy, a key component of individual fitness; (2) genetic diversity was positively correlated to the number of dispersing individuals (indicative of landscape functional connectivity) and adult population size; (3) parameters inferred from capture-recapture procedures (population size and dispersal events between patches) correlated much better with genetic diversity than estimates usually used as surrogates for population size (patch area and descriptors of habitat quality) and dispersal (structural connectivity index).

CONCLUSION

Our results suggest that dispersal is a very important factor maintaining genetic diversity. Even at a very local spatial scale in a metapopulation consisting of large high-density populations interconnected by considerable dispersal rates, genetic diversity can be decreased and directly affect the fitness of individuals. From a biodiversity conservation perspective, this study clearly shows the benefits of both in-depth demographic and genetic analyses. Accordingly, to ensure the long-term survival of populations, conservation actions should not be blindly based on patch area and structural isolation. This result may be especially pertinent for species at their range margins, particularly in this era of rapid environmental change.

Genetic population structure of the vulnerable bog fritillary butterfly

Populations of the bog fritillary butterfly Proclossiana eunomia (Lepidoptera, Nymphalidae) occur in patchy habitat in central and western Europe. P. eunomia is a vulnerable species in the Belgian Ardennes and the number of occupied sites has significantly decreased in this region since the 1960s. RAPD (random amplified polymorphic DNA) markers were used to study the consequences of habitat loss and fragmentation on the genetic population structure of this species. Gene diversity was lower in populations with smaller population sizes. Genetic subdivision was high (Fst=0.0887) considering the small spatial scale of this study (150 km2). The most geographically isolated population was also the most genetically differentiated one. The genetic population structure and genetic differentiation detected in this study were explained by (1) differences in altitude of the sampled locations and, (2) lower dispersal propensity and dispersal rate in fragmented landscapes versus continuous landscapes. Results from the RAPD analyses were compared with a previous allozyme based study on the same populations. The results of this study suggest that increased fragmentation has lead to a greater genetic differentiation between remaining P. eunomia populations.

Gene flow and functional connectivity in the natterjack toad

Functional connectivity is a key factor for the persistence of many specialist species in fragmented landscapes. However, connectivity estimates have rarely been validated by the observation of dispersal movements. In this study, we estimated functional connectivity of a real landscape by modelling dispersal for the endangered natterjack toad (Bufo calamita) using cost distance. Cost distance allows the evaluation of 'effective distances', which are distances corrected for the costs involved in moving between habitat patches in spatially explicit landscapes. We parameterized cost-distance models using the results of our previous experimental investigation of natterjack's movement behaviour. These model predictions (connectivity estimates from the GIS study) were then confronted to genetic-based dispersal rates between natterjack populations in the same landscape using Mantel tests. Dispersal rates between the populations were inferred from variation at six microsatellite loci. Based on these results, we conclude that matrix structure has a strong effect on dispersal rates. Moreover, we found that cost distances generated by habitat preferences explained dispersal rates better than did the Euclidian distances, or the connectivity estimate based on patch-specific resistances (patch viscosity). This study is a clear example of how landscape genetics can validate operational functional connectivity estimates.

Phylogeography of Aglais urticae (Lepidoptera) based on DNA sequences of the mitochondrial COI gene and control region

Mitochondrial DNA (mtDNA) sequences of the COI gene and the control region were used to examine the genetic population structure of Aglais urticae L. (Lepidoptera) over its entire geographic range, i.e., the Palaearctic. The phylogenetic relationships within and between A. urticae subspecies were determined and patterns of mtDNA divergence and ecological differentiation were compared. High gene flow together with a recent and sudden population expansion characterise the genetic population structure of this species. No geographically induced differentiation was observed, nor were subspecies identified as separate evolutionary units. The discrepancy between the genetic and ecological variation is most likely due to the slower rate of mtDNA evolution compared to ecological differentiation. The control region proved to be a less useful molecular marker for the population genetics and the phylogenetic reconstruction of closely related taxa in A. urticae than it has for other species. The extreme bias in adenine and thymine content (A+T=90.91%) probably renders this region highly susceptible to homoplasy, resulting in a less informative molecular marker.

The genetic structure of endangered populations in the Cranberry Fritillary, Boloria aquilonaris (Lepidoptera, Nymphalidae): RAPDs vs allozymes

The genetic population structure of the Cranberry Fritillary Boloria aquilonaris was studied using both RAPDs (random amplified polymorphic DNA) and allozymes. In Belgium, B. aquilonaris has a naturally fragmented distribution that has been accentuated due to human activity during the last century. The genetic population structure of this butterfly was analysed at the regional (several Ardenne uplands) and at the landscape level (several populations within an Ardenne upland). Both population genetic markers confirmed results from a previous CMR study at the landscape scale. At the regional scale however, important incongruences were observed between RAPDs and allozymes. The average gene diversity for the RAPD data was twice that of the allozyme data. The degree of population subdivision was also much greater for RAPDs than for allozymes. The UPGMA clusters produced by each of these markers differed significantly. We believe that, given the higher rate of mutation of RAPDs and the greater number of loci assayed by this method, RAPDs reveal a more accurate and recent population genetic structure than allozymes.

Spatial and temporal population genetic structure of the butterfly aglais urticae L. (Lepidoptera, nymphalidae)

The genetic diversity and the temporal and spatial genetic population structure of the butterfly Aglais urticae, a highly mobile species, were studied by allozyme electrophoresis. High levels of allozyme diversity were found. Most of the total genetic diversity occurred at the within-population scale rather than at the between-population scale. This variation could not be accounted for by Wright's model of 'isolation by distance'. No significant temporal variation was observed for those populations that were sampled in different years. A process combining high movement rate between neighbouring patches, long-distance migration and rare extinction/recolonization is suggested to explain the observed genetic structure. This hypothesis is favoured over an island model of population structure because migration in A. urticae is uniform neither with distance nor with time.