Showing papers by "Vincent Bretagnolle published in 2017"

The carry‐over effects of pollen shortage decrease the survival of honeybee colonies in farmlands

Abstract: 1. Many studies have reported honeybee colony losses in human-dominated landscapes. While bee floral food resources have been drastically reduced over past decades in humandominated landscapes, no field study has yet been undertaken to determine whether there is a carry-over effect between seasonal disruption in floral resource availability and high colony losses. 2. We investigated if a decline in the harvest of pollen by honeybees in spring affected managed honeybee colony dynamics (brood size, adult population and honey reserves) and health (Varroa mite loads and colony survival) throughout the beekeeping season. 3. A decline in pollen harvest was associated with a direct reduction in brood production, leading to a negative effect on the adult population size later in the season, and lower honey reserves before the onset of winter. Furthermore, the decline in pollen harvest negatively impacted the health of the colony, resulting in higher Varroa mite loads and higher seasonal and winter colony losses. 4. Early-warning signs of these carry-over effects were identified, showing that preferential investment in honey reserves instead of brood production early in the season increased the decline in pollen harvest and its associated carry-over effects. 5. Synthesis and applications. The results suggest that the decline in pollen harvest may have been overlooked as a cause of pollen shortage and associated bee colony losses. Strategies to avoid such losses in intensive farmland systems include (i) limiting or avoiding honey harvests in spring, (ii) monitoring colonies for early-warning signals of colony failure and (iii) increasing the amount of floral resources available through wise land-use management.

Predictive systems models can help elucidate bee declines driven by multiple combined stressors

Abstract: Bee declines are driven by multiple combined stresses, making it exceedingly difficult to identify experimentally the most critical threats to bees and their pollination services. We highlight here the too often ignored potential of mechanistic models in identifying critical stress combinations. Advanced bee models are now available as open access tools and offer an unprecedented opportunity for bee biologists to explore bee resilience tipping points in a variety of environmental contexts. We provide general guidelines on how to run bee models to help detect a priori critical stress combinations to be targeted in the field. This so-called funnel analysis should be performed in tight conjunction with the recent development of large-scale field monitoring programs for bee health surveillance.

Individual variation in behavioural responsiveness to humans leads to differences in breeding success and long-term population phenotypic changes.

Abstract: Whether human disturbance can lead to directional selection and phenotypic change in behaviour in species with limited behavioural plasticity is poorly understood in wild animal populations. Using a 19-year study on Montagu's harrier, we report a long-term increase in boldness towards humans during nest visits. The probability of females fleeing or being passive during nest visits decreased, while defence intensity steadily increased over the study period. These behavioural responses towards humans were significantly repeatable. The phenotypic composition of the breeding population changed throughout the study period (4-5 harrier generations), with a gradual disappearance of shy individuals, leading to a greater proportion of bolder ones and a more behaviourally homogeneous population. We further show that nest visit frequency increased nest failure probability and reduced productivity of shy females, but not of bold ones. Long-term research or conservation programmes needing nest visits can therefore lead to subtle but relevant population compositional changes that require further attention.

Spatiotemporal dynamics of the agricultural landscape mosaic drives distribution and abundance of dominant carabid beetles

Abstract: Agroecosystems are dynamic, with yearly changing proportions of crops. Explicit consideration of this temporal heterogeneity is required to decipher population and community patterns but remains poorly studied. We evaluated the impact on the activity-density of two dominant carabid species (Poecilus cupreus and Anchomenus dorsalis) of (1) local crop, current year landscape composition, and their interaction, and (2) inter-annual changes in landscape composition due to crop rotations. Carabids were sampled using pitfall-traps in 188 fields of winter cereals and oilseed rape in three agricultural areas of western France contrasting in their spatial heterogeneity. We summarized landscape composition in the current and previous years in a multi-scale perspective, using buffers of increasing size around sampling locations. Both species were more abundant in oilseed rape, and in landscapes with a higher proportion of oilseed rape in the previous year. P. cupreus abundance was negatively influenced by oilseed rape proportion in the current year landscape in winter cereals and positively by winter cereal proportion in oilseed rape. A. dorsalis was globally impacted at finer scales than P. cupreus. Resource concentration and dilution-concentration processes jointly appear to cause transient dynamics of population abundance and distribution among habitat patches. Inter-patch movements across years appear to be key drivers of carabids’ survival and distribution, in response to crop rotation. Therefore, the explicit consideration of the spatiotemporal dynamics of landscape composition can allow future studies to better evidence ecological processes behind observed species patterns and help developing new management strategies.

Influence of the surrounding landscape on the colonization rate of cereal aphids and phytovirus transmission in autumn

Abstract: Ecological control has often focused on factors enhancing control of pests by their natural enemies, while factors reducing the colonization rate of crops by pests have been comparatively neglected. We present an approach to assess landscape influence on the intensity of wheat colonization by a major crop pest, the aphid Rhopalosiphum padi. We used trays containing wheat seedlings to monitor field colonization by R. padi and barley yellow dwarf viruses’ transmission in two areas in France in autumn. We assessed the influence of landscape components likely affecting aphid colonization, i.e. maize and grasslands as source of migrants on the number of aphids landing per tray, as well as the host plant of origin and the viruliferous potential of migrants. During the survey, maize was the main source of migrants. Virus transmission was detected in a few cases (4 % positive assays). Colonization was increased by the presence of maize, but reduced by the presence of grasslands at the landscape scale considered here (i.e. at a radius of 1000 m). Our study contributes to a better understanding of disease dynamics in agricultural landscapes. By identifying features of the landscape that surrounds fields and affects these dynamics, growers can develop more efficient crop protection strategies relying on habitat manipulation and rational use of pesticides.

A circannual perspective on daily and total flight distances in a long-distance migratory raptor, the Montagu's harrier, Circus pygargus .

Abstract: Long-distance migrants are particularly recognized for the distances covered on migration, yet little is known about the distances they cover during the rest of the year. GPS-tracks of 29 Montagu's harriers from breeding areas in France, The Netherlands and Denmark showed that harriers fly between 35 653 and 88 049 km yr-1, of which on average only 28.5% is on migration. Mean daily distances during migration were 296 km d-1 in autumn and 252 km d-1 in spring. Surprisingly, males' daily distances during breeding (217 km d-1) were close to those during migration, whereas breeding females moved significantly less (101 km d-1) than males. In terms of flight distance, the breeding season seemed nearly as demanding as migration periods for males. During the six winter months, both sexes moved less (114 and 128 km d-1 for females and males, respectively) than during migration. Harriers therefore covered shorter daily distances during winter which might allow birds to compensate for the more demanding phases of migration and breeding.

Geographical generality of bird-habitat relationships depends on species traits

Abstract: Aim: The environmental filtering process is often considered as static in ecological studies. However, growing evidence shows that species-environment relationships vary in space and time. In this study, we assessed to what extent bird responses to landscape components can be geographically generalised and whether differences in response generality can be explained by traits. Location: France. Methods: We collected a large bird data set (1968 point counts over two years) with a standardised protocol in three agricultural regions with different levels of intensification in France. We modelled the relationships between the distribution of 26 bird species and three landscape components (percentage of woodland, hedgerow density and landscape heterogeneity) and assessed whether differences between regions in bird responses to landscape components (i.e., landscape-region interactions) can be explained by three species traits (habitat specialisation, diet and migration strategy). We also examined the response of total species richness. Results: We found that 16 species showed regional differences in their response at least for one of the three landscape variables. Importance of landscape-region interactions was significantly correlated with two species traits. Responses of specialist species to landscape components were geographically more constant than those of generalists. The geographical variability of responses was higher for migrants than for sedentary species. There were no significant relationships for the diet trait. Species richness responded positively to the three landscape metrics in a similar way in the three regions. Main conclusions: The results underline the need to take into account the spatial differences between species responses to habitats according to their traits when modelling species-habitat relationships at large scales. From a conservation point of view, we suggest that conservation measures could be generalised at a large scale for specialist species which are declining in agricultural landscapes.

Modelling unbiased dispersal kernels over continuous space by accounting for spatial heterogeneity in marking and observation efforts

Abstract: Although a key demographic trait determining the spatial dynamics of wild populations, dispersal is notoriously difficult to estimate in the field. Indeed, dispersal distances obtained from the monitoring of marked individuals typically lead to biased estimations of dispersal kernels as a consequence of (i) restricted spatial scale of the study areas compared to species potential dispersal and (ii) heterogeneity in marking and observation efforts and therefore in detection probability across space. Here, we propose a novel method to circumvent these issues that does not require data on observation effort per se, to correct for the variability in detection of marked individuals across space. Observed dispersal events were weighted by the distribution of departure points and an eroded spatial window approach was applied so as to deal with border effect. We conducted a set of simulations which indicated that our method was successful in correcting the effect of spatially heterogeneous detectability and produce unbiased dispersal kernels. We applied this method to a real dataset on the Montagu's harrier (>5,000 chicks tagged), providing c. 6,000 resightings collected in entire France by a network of 1,200 volunteers within a citizen-science programme. The median dispersal distance observed was 32 km (range: 0.1–627 km). Once corrected for spatial heterogeneity in marking and observation efforts and border effect, the modelled dispersal kernel indicated a median dispersal distance of 78–123 km depending on the spatial scale considered (constrained within French borders or not, respectively). Synthesis and applications: The current rise of citizen-science programmes is likely to stretch our estimate of the ecologically relevant spatial scale at which dispersal takes place for many taxa. Our method is particularly suited for such large-scale data that typically suffer from high spatial heterogeneity in marking and observation efforts and offers the possibility to derive unbiased dispersal kernels, a key component for modelling population dynamics and species distribution in a context of environmental change. Currently, our method assumes homogeneity in both habitat and dispersal behaviour across individuals. We discuss, however, how to relax these hypotheses to further investigate the effect of, e.g. local conspecific density or habitat quality on dispersal propensity.

Population expansion, current and past gene flow in Gould’s petrel: implications for conservation

Abstract: Seabird life-history traits such as long generation time, low annual fecundity and delayed sexual maturation make them more prone to population loss and consequently to extinction; petrels are indeed amongst the most threatened birds. Based on coalescence and multiloci inference this study examines the extent of genetic differentiation of a vulnerable New Caledonia (caledonica) and Australia (leucoptera) subspecies of Pterodroma leucoptera (Gould’s Petrel), and whether the genetic relationship between them results from the influence of past events like variation in sea level, or is dominated by contemporary gene flow. Sequences of two mitochondrial genes and five nuclear introns were obtained from 86 individuals from both populations. Haplotype networks were used to infer relationships between the haplotypes of both populations. The demographic history of the P. leucoptera complex was studied using neutrality tests and Extended Bayesian Skyline Plots. A weak population differentiation was revealed. The Extended Bayesian Skyline plot suggested a population expansion approximately 80,000 years before present (bp) for caledonica and 30,000 years bp for leucoptera. The split was dated to 30,000 years bp by means of multilocus inference through *BEAST. Despite genetic similarity of the two taxa, we advocate to consider them as independent units for conservation management, given their strong ecological distinctiveness (foraging distribution, winter distribution, breeding phenology and breeding distribution).

Towards better traceability of field sampling data

Abstract: Ensuring traceability of field experimental data or laboratory sampling data to conduct reproducible research is a challenge at the present time. Between the time when geolocalized specimens (biotic or abiotic) are taken, and the time the resulting data ends up in analysis published within a study, many manual operations take place and may generate errors. The French LTSER have joined forces at the national level to propose a solution as generic as possible to this problem of monitoring of the samples and the data associated with them. Compared to existing solutions (such as Laboratory Information Management Systems), we target a robust labeling solution adapted to outdoor working conditions, with the management of stocks and movements of samples. We designed and realized a prototype tested from end to end, using an open source software (https://github.com/Irstea/collec), cheap Zebra printers (mobile or not) and raspberries as devices. This solution provides sufficient flexibility for the wide variety of existing protocols. Its strength is the record of all contextual data associated with the samples, which constitute important parameters of the subsequent analyzes. At last, not only traceability is guaranteed, but also a gain of time and a rationalization of the storage of samples that will induce a return on investment.

Towards a semantic framework for exploiting heterogeneous environmental data

Abstract: This paper presents the 'Environment and landscape geo-knowledge' GEMINAT project which aims to build an infrastructure favouring the cross-analysis of spatio-temporal heterogeneous data sources recorded at the Chize environmental observatory since 1994. From a case study, we summarise the difficulties encountered by biologists and ecologists when maintaining and analysing collected environmental data, essentially the spatial organisation of the landscape, crop rotation, and wildlife data. We show how a framework which uses a spatio-temporal ontology as a semantic mediator can solve challenges related to the analysis and maintenance of these heterogeneous data.

Database Of Weeds In Cultivation Fields Of France And Uk, With Ecological And Biogeographical Information

Abstract: The database includes a list of 1577 weed plant taxa found in cultivated fields of France and UK, along with basic ecological and biogeographical information. The database is a CSV file in which the columns are separated with comma, and the decimal sign is ".". It can be imported in R with the command "tax.discoweed <- read.csv("tax.discoweed_18Dec2017_zenodo.csv", header=T, sep=",", dec=".", stringsAsFactors = F)" Taxonomic information is based on TaxRef v10 (Gargominy et al. 2016), - 'taxref10.CD_REF' = code of the accepted name of the taxon in TaxRef, - 'binome.discoweed' = corresponding latine name, - 'family' = family name (following APG III), - 'taxo' = taxonomic rank of the taxon, either 'binome' (species level) or 'infra' (infraspecific level), - 'binome.discoweed.noinfra' = latine name of the superior taxon at species level (different from 'binome.discoweed' for infrataxa), - 'taxref10.CD_REF.noinfra' = code of the accepted name of the superior taxon at species level. The presence of each taxon in one or several of the following data sources is reported: - Species list from a reference flora (observations in cultivated fields over the long term, without sampling protocol), * 'jauzein' = national and comprehensive flora in France (Jauzein 1995), - Species lists from plot-based inventories in cultivated fields, * 'za' = regional survey in 'Zone Atelier Plaine & Val de Sevre' in SW France (Gaba et al. 2010), * 'biovigilance' = national survey of cultivated fields in France (Biovigilance, Fried et al. 2008), * 'fse' = Farm Scale Evaluations in England and Scotland, UK (Perry, Rothery, Clark et al., 2003), * 'farmbio' = Farm4Bio survey, farms in south east and south west of England, UK (Holland et al., 2013) - Reference list of segetal species (species specialist of arable fields), * 'cambacedes' = reference list in France (Cambacedes et al. 2002) Life form information is extracted from Julve (2014) and provided in the column 'lifeform'. The classification follows a simplified Raunkiaer classification (therophyte, hemicryptophyte, geophyte, phanerophyte-chamaephyte and liana). Regularly biannual plants are included in hemicryptophytes, while plants that can be both annual and biannual are assigned to therophytes. Biogeographic zones are also extracted from Julve (2014) and provided in the column 'biogeo'. The main categories are 'atlantic', 'circumboreal', 'cosmopolitan, 'Eurasian', 'European', 'holarctic', 'introduced', 'Mediterranean', 'orophyte' and 'subtropical'. In some cases, a precision is included within brackets after the category name. For instance, 'introduced(North America)' indicates that the taxon is introduced from North America. In addition, some taxa are local endemics ('Aquitanian', 'Catalan', 'Corsican', 'corso-sard', 'ligure', 'Provencal'). A single taxon is classified 'arctic-alpine'. Red list status of weed taxa is derived for France and UK: - 'red.FR' is the status following the assessment of the French National Museum of Natural History (2012), - 'red.UK' is based on the Red List of vascular plants of Cheffings and Farrell (2005), last updated in 2006. The categories are coded following the IUCN nomenclature. A habitat index is provided in column 'module', derived from a network-based analysis of plant communities in open herbaceous vegetation in France (Divgrass database, Violle et al. 2015, Carboni et al. 2016). The main habitat categories of weeds are coded following the Divgrass classification, - 1 = Dry calcareous grasslands - 3 = Mesic grasslands - 5 = Ruderal and trampled grasslands - 9 = Mesophilous and nitrophilous fringes (hedgerows, forest edges...) Taxa belonging to other habitats in Divgrass are coded 99, while the taxa absent from Divgrass have a 'NA' value. Two indexes of ecological specialization are provided based on the frequency of weed taxa in different habitats of the Divgrass database. The indexes are network-based metrics proposed by Guimera and Amaral (2005), - c = coefficient of participation, i.e., the propensity of taxa to be present in diverse habitats, from 0 (specialist, present in a single habitat) to 1 (generalist equally represented in all habitats), - z = within-module degree, i.e., a standardized measure of the frequency of a taxon in its habitat; it is negatve when the taxon is less frequent than average in this habitat, and positive otherwise; the index scales as a number of standard deviations from the mean.

Applying ecology to the innovative design of sustainable agroecosystems

Abstract: Meeting the future challenges of the Anthropocene requires designing innovative and sustainable agroecosystems. Ecological knowledge is expected to be an important component of such endeavor. Drawing on recent design theories, we present a study of a French agroecosystems in which we assess the potential of using ecological knowledge in agroecosystem participatory design processes. We show that design processes generate various acceptable agroecosystem configurations and open management alternatives that were not initially identified by researchers. This research highlights that ecological science is critical for designing sustainable agroecosystems, because it orients the design process by identifying key ecological properties that must be maintained, while opening the range of management options stakeholders can explore. Infrastructures supporting participatory design processes, built on to ecology research centers, such as Long Term social-ecological Research sites, could become new cornerstones of technical and governance innovation for sustainable agroecosystems.

QR-CODE PROJECT : Towards better traceability of field sampling data

Abstract: Ensuring traceability of field experimental data or laboratory sampling data to conduct reproducible research is a challenge at the present time. Between the time when geolocalized specimens (biotic or abiotic) are taken, and the time the resulting data ends up in analysis published within a study, many manual operations take place and may generate errors. The French LTSER have joined forces at the national level to propose a solution as generic as possible to this problem of monitoring of the samples and the data associated with them. Compared to existing solutions (such as Laboratory Information Management Systems), we target a robust labeling solution adapted to outdoor working conditions, with the management of stocks and movements of samples. We designed and realized a prototype tested from end to end, using an open source software (https://github.com/Irstea/collec), cheap Zebra printers (mobile or not) and raspberries as devices. This solution provides sufficient flexibility for the wide variety of existing protocols. Its strength is the record of all contextual data associated with the samples, which constitute important parameters of the subsequent analyzes. At last, not only traceability is guaranteed, but also a gain of time and a rationalization of the storage of samples that will induce a return on investment.

The type of Rapa Shearwater Puffinus (newelli?) myrtae from the Austral Islands, Polynesia, with remarks on the morphological variation of the taxon

Abstract: Rapa Shearwater Puffinus (newelli?) myrtae is known solely from five specimens held in Tring and Paris museums, and from observations on the breeding islands. It has a potentially tiny breeding population that is apparently restricted currently to islets off Rapa (it formerly also bred on the main island of Rapa), as well as probably on Marotiri (south of Rapa), in the Austral Islands, Polynesia. Clear differences in morphology between the series in Paris and the holotype in Tring can be explained in terms of age-related variation, with the latter specimen being a juvenile. As a result, we describe adult plumage in detail for the first time. Genetic analysis confirmed that the Paris and Tring specimens can be unequivocally referred to the same taxon.

Système d’information spatiotemporel pour l’intégration et l’exploitation de données environnementales

Abstract: Cet article presente une solution open-source pour l’acquisition et l’exploitation de donnees environnementales heterogenes collectees sur la zone atelier Plaine et Val de Sevre. En presentant les systemes d’information geographique facilitant la gestion de differentes donnees de l’observatoire environnemental de Chize, notamment les bases de donnees sur l’assolement et l’avifaune, nous identifions les besoins d’analyse spatio-temporelle des experts biologistes et ecologues vis-a-vis de ces bases heterogenes. Nous montrons comment la mise en œuvre d’un framework base sur une ontologie spatio-temporelle peut resoudre les difficultes d’analyse et de maintenance qu’induisent ces systemes, amenes a de constantes evolutions de leurs modeles. En particulier, la demonstration de la faisabilite d’un tel systeme est faite, et nous testons sa capacite a repondre a des requetes complexes melant plusieurs sources de donnees et les dimensions spatiales et temporelles.