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Arctic Migrations Shape Global Meta‐Communities: Contrasting Insights From Species Occurrence, Abundance and Biomass
No full textInternational audienceAimSeasonally migratory species generate large movements of organisms and biomass between distant breeding and non-breeding grounds. However, our understanding of how migratory species shape global networks of interconnected communities (meta-communities) remains limited. Migratory links between communities can be measured in different ways (e.g., species occurrence, abundance or biomass), each providing complementary information by modulating the relative importance of species in meta-communities. We aim at investigating to what extent measuring migratory links using species occurrence, abundance or biomass can reveal alternative structures (i.e., topology) in a meta-community linking an Arctic breeding ground to remote non-breeding grounds.LocationWe use as a study case the High-Arctic vertebrate community of Bylot Island (Nunavut, Canada), along with ecoregions of North and South America, Europe and Africa.Time PeriodPresent.Major Taxa StudiedTerrestrial Arctic birds (30 species) and mammals (5 species).MethodsWe first consider species occurrence at the non-breeding grounds to define migratory links within the meta-community. Secondly, we measure the number of individuals and the amount of biomass travelling along those links. Finally, we compare the meta-community structure under each scenario using a migration network representation.ResultsPatterns of species occurrence, abundance and biomass reveal that temperate ecoregions of South and especially North America maintain strong ecological connections with the vertebrate community of Bylot Island. However, the structural role of species within the network can vary substantially depending on how migratory links are measured (i.e., contrasting topological anomalies). Using abundance or biomass to measure migratory links results in a finer partitioning of the network into modules compared to using species occurrence alone.Main ConclusionsWe highlight that using different metrics of migratory links reveals unique, yet complementary structural features of meta-communities. These findings contribute to assessing the vulnerability of communities to perturbations occurring in distant but connected environments through migration
Le prestre et les deus ribaus - Édité d'après le ms. BnF fr. 837
No full textLe prestre et les deus ribaus - Édité d'après le ms. BnF fr. 83
Le foteor - Édité d'après le ms. BnF fr. 19152
No full textLe foteor - Édité d'après le ms. BnF fr. 1915
Gonbaut - Édité et traduit d'après le ms. de la BM de Troyes 1511
No full textGonbaut - édité et traduit d'après le ms. de la BM de Troyes 151
Natural insurance as a green alternative for farmers? Empirical evidence for semi-natural habitats and methodological bias
No full textInternational audienceNatural insurance based on the provision of ecosystem services is a promising tool for the future of agriculture. However, empirical evidence of the role it can play is lacking, and its integration into standard insurance strategies – for example, the use of pesticides or market-based insurance – has been understudied. To begin to fill this gap, this study developed an original conceptual framework to estimate the insurance value provided by semi-natural habitats in a crop production context. The framework was then applied to a case study in western France, focusing on the value of natural pest control provided by grassland areas in the context of oilseed rape production. We evaluated the insurance role of grasslands for pest control and estimated this at a value of €50 per hectare. However, this estimation varied greatly according to the farmer’s risk-mitigation strategies considered. We found that omitting agricultural inputs (e.g. risk-mitigating inputs such as pesticides) overestimated the insurance value of grassland areas due to the substitution effect between different types of insurance tools. Despite this variation, the findings show that it is nonetheless always optimal for farmers to maintain grassland areas to manage risk. This study provides empirical evidence of the insurance role of semi-natural habitats in an agricultural production context and offers new arguments for the ecological intensification of agriculture
Hydrothermal physiology and vulnerability to climatic change: insight from European vipers
No full textInternational audienceClarifying physiological adaptations is crucial to understand species distribution and predict vulnerability to changing climatic conditions. Considering energy and water constraints jointly is necessary because these facets are intertwined in ectotherms. The genus Vipera is a diversified group of Palearctic snakes with parapatric distributions and contrasted climatic affinities. These species are active thermoregulators relying on basking to maintain their body temperature. While some species such as V. berus and V. seoanei are adapted to cold and wet environments, other species have intermediate (temperate-oceanic) affinities (V. aspis), and some such as V. latastei and V. ammodytes inhabit warm and semi-arid climates. We studied physiological traits related to energy and water balance in these five species to better understand species' vulnerability to climate change. First, using open-flow respirometry we quantified standard metabolic rate (SMR) and evaporative water loss (TEWL) at three temperatures (15 • C, 25 • C and 33 • C). Cold-and wet-adapted species exhibited higher metabolic rates and evaporative water loss, reflecting adaptations to colder, wetter environments, while warm-and dry-adapted species showed lower rates. Second, we used these data to investigate their physiological responses to extreme climatic events (ECE). Simulated responses to summer heat spells revealed a major increase in energy expenditure and water loss rates across species. However, the effect was more prominent in cold-and wetadapted species. This study underscores the physiological constraints that cold and wet-adapted species face during extreme climate events, providing insights into the vulnerabilities of ectotherms to ongoing environmental changes
Long-term salinity exposure reveals site-specific physiological and behavioural responses in coastal and inland toads
No full textInternational audienceSalinization is a global phenomenon affecting many coastal and inland water bodies at unprecedented rates, and having multiple consequences for wildlife, mostly due to the high metabolic cost of osmoregulation. Most research on salinity effects has focused on juvenile life stages and short-term exposures. In this study, we evaluated the impact of chronic exposure (7 months) to environmental salinity (0, 2 or 4 g l−1) in adult individuals of a widespread amphibian species, the spined toad (Bufo spinosus), originating either from coastal (salt-exposed) or inland (naive to salinity) environments. Coastal and inland individuals, irrespective of their experimental exposure to salinity, differed post-experimental exposure in telomere length, cutaneous permeability, defensiveness and foraging behaviours, but unexpectedly not in triiodothyronine and testosterone levels, and mass-specific metabolic rate. As pre-exposure data were unavailable for some of these traits (metabolic rate, cutaneous permeability and behaviour), these differences may reflect either intrinsic population-level variation or population-specific responses to treatment. Coastal individuals exhibited compensatory growth in freshwater, suggesting differential energy allocation. Chronic exposure to moderate salinity increased osmolality and triiodothyronine levels while reducing growth and preferred temperature. Interestingly, defensiveness and thermal preference were more affected by exposure to salinity in coastal individuals. Despite their saline environment, these toads also showed higher skin permeability to water flux, potentially facilitating water uptake to counter salinity stress. Our study demonstrates that salinization can have negative effects on critical traits of adult anurans, and emphasizes the importance of increasing research effort on the impact of salinity on wildlife including both experimental and long-term field studies
Genetic and transcriptomic analysis of a Saccharina latissima segregating F2 family detects groups of individuals with different responses to temperature stress
No full textInternational audienceSaccharina latissima is an important species for the emerging seaweed aquaculture industry in the northern Atlantic. In this study, genotype and phenotype data for a segregating F2 family was used to generate a highdensity genetic map for S. latissima and to identify temperature-stress-related quantitative trait loci (QTLs). A temperature stress experiment detected distinct phenotypic classes with different stress responses within the F2 family and these phenotypic classes were shown to exhibit different transcriptomic responses to heat stress. The existence of heat tolerant, resilient and sensitive individuals within this segregating family indicates that it should be possible to breed temperature tolerant strains of S. latissima. This conclusion was supported by the identification of three QTLs that influenced recovery after temperature stress. The results of this study and the resources generated, in particular the high-density genetic map, represent an important foundation for future S. latissima breeding programs.</div
Habitat availability is insufficient to explain regional variations in white stork breeding habitat preference
No full textInternational audienceUnderstanding species-habitat associations is key for making predictions of species distributions of relevance to ecology and conservation. Regional differences in species habitat preferences can hinder the transferability of habitat models in space and time, but our ability to account for these differences will depend on the mechanisms underlying them (differences in habitat availability, genetics, culture). Here, we modelled the large-scale breeding distribution of an expanding species, the white stork Ciconia ciconia in France, applying machine-learning algorithms to an extensive dataset of the distribution of nests spanning the whole country. Specifically, we assessed the transferability of the models across different geographic zones and contrasted the modelled nesting habitat preferences of the species across these zones. Finally, we assessed whether local differences in model transferability were related to habitat availability in each zone. Our models generally had good calibration performances, but were not equally transferable to all zones. Additionally, environmental variables did not have the same effects in the different zones, with particularly striking differences between Alsace and the rest of France. This included a certain preference for urban areas in Alsace -absent from other zones -that was consistent with their tendency to nesting on buildings in that zone. Differences in habitat availability between Alsace and the rest of France, as well as connectivity within the French white stork metapopulation appeared to be insufficient to explain the lack of transferability of models to this zone, suggesting some possible local historical and cultural effects on habitat selection.</div
