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15 juin 2018

The economics of fishing the high seas [Science Advances]

While the ecological impacts of fishing the waters beyond national jurisdiction (the “high seas”) have been widely studied, the economic rationale is more difficult to ascertain because of scarce data on the costs and revenues of the fleets that fish there. Newly compiled satellite data and machine learning now allow us to track individual fishing vessels on the high seas in near real time. These technological advances help us quantify high-seas fishing effort, costs, and benefits, and assess whether, where, and when high-seas fishing makes economic sense. We characterize the global high-seas fishing fleet and report the economic benefits of fishing the high seas globally, nationally, and at the scale of individual fleets.(...)

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12 juin 2018

Matrix Models of Hierarchical Demography : Linking Group- and Population-Level Dynamics in Cooperative Breeders [The American Naturalist]

Keywords : matrix models, population dynamics, hierarchical demography, social species, cooperative breeders, Allee effects.

For highly social species, population dynamics depend on hierarchical demography that links local processes, group dynamics, and population growth. Here, we describe a stage-structured matrix model of hierarchical demography, which provides a framework for understanding social influences on population change. Our approach accounts for dispersal and affords insight into population dynamics at multiple scales. The method has close parallels to integral projection models but focuses on a discrete characteristic (group size). Using detailed long-term records for meerkats (Suricata suricatta), we apply our model to explore patterns of local density dependence and implications of group size for group and population growth.(...)

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11 juin 2018

Captivity and exposure to the emerging fungal pathogen Batrachochytrium salamandrivorans are linked to perturbation and dysbiosis of the amphibian skin microbiome [BioRxiv]

The emerging fungal pathogen, Batrachochytrium salamandrivorans (Bsal) is responsible for the catastrophic decline of European salamanders and poses a threat to amphibians globally. The amphibian skin microbiome is strongly associated with disease outcome for several host-pathogen systems, yet its role in Bsal infection remains unresolved. In addition, many in-vivo Bsal studies to date have relied on specimens that have been kept in captivity for long periods without considering the influence of environment on the microbiome and how this may impact the host response to pathogen exposure. We characterised the impact of captivity and exposure to Bsal on the skin bacterial and fungal communities of two co-occurring European newt species, the smooth newt (Lissotriton vulgaris) and the great-crested newt (Triturus cristatus).(...)

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8 juin 2018

Matching consumer feeding behaviours and resource traits : a fourth‐corner problem in food‐web theory [Ecology Letters]

Keywords : community structure, dimensionality, ecological networks, latent variables

For decades, food web theory has proposed phenomenological models for the underlying structure of ecological networks. Generally, these models rely on latent niche variables that match the feeding behaviour of consumers with their resource traits. In this paper, we used a comprehensive database to evaluate different hypotheses on the best dependency structure of trait‐matching patterns between consumers and resource traits. We found that consumer feeding behaviours had complex interactions with resource traits ; however, few dimensions (i.e. latent variables) could reproduce the trait‐matching patterns. We discuss our findings in the light of three food web models designed to reproduce the multidimensionality of food web data ; additionally, we discuss how using species traits clarify food webs beyond species pairwise interactions and enable studies to infer ecological generality at larger scales, despite potential taxonomic differences, variations in ecological conditions and differences in species abundance between communities.

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7 juin 2018

Environment and host as large-scale controls of ectomycorrhizal fungi [Nature]

Keywords : forest ecology, fungal ecology, macroecology, microbial ecology, plant symbiosis

Explaining the large-scale diversity of soil organisms that drive biogeochemical processes—and their responses to environmental change—is critical. However, identifying consistent drivers of belowground diversity and abundance for some soil organisms at large spatial scales remains problematic. Here we investigate a major guild, the ectomycorrhizal fungi, across European forests at a spatial scale and resolution that is—to our knowledge—unprecedented, to explore key biotic and abiotic predictors of ectomycorrhizal diversity and to identify dominant responses and thresholds for change across complex environmental gradients. We show the effect of 38 host, environment, climate and geographical variables on ectomycorrhizal diversity, and define thresholds of community change for key variables. We quantify host specificity and reveal plasticity in functional traits involved in soil foraging across gradients. We conclude that environmental and host factors explain most of the variation in ectomycorrhizal diversity, that the environmental thresholds used as major ecosystem assessment tools need adjustment and that the importance of belowground specificity and plasticity has previously been underappreciated.

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