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13 juillet 2018

Dynamics of Gut Microbiota Diversity During the Early Development of an Avian Host : Evidence From a Cross-Foster Experiment [Frontiers in Microbiology]

Joël White

Despite the increasing knowledge on the processes involved in the acquisition and development of the gut microbiota in model organisms, the factors influencing early microbiota successions in natural populations remain poorly understood. In particular, little is known on the role of the rearing environment in the establishment of the gut microbiota in wild birds. Here, we examined the influence of the nesting environment on the gut microbiota of Great tits (Parus major) by performing a partial cross-fostering experiment during the intermediate stage of nestling development. We found that the cloacal microbiota of great tit nestlings underwent substantial changes between 8 and 15 days of age, with a strong decrease in diversity, an increase in the relative abundance of Firmicutes and a shift in the functional features of the community. Second, the nesting environment significantly influenced community composition, with a divergence among separated true siblings and a convergence among foster siblings. Third, larger shifts in both microbiota diversity and composition correlated with lower nestling body condition.(...)

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13 juillet 2018

Overcoming the Data Crisis in Biodiversity Conservation [TREE - Opinion]

Diagnosing the conservation status of many species is hampered by insufficient data. Modern computer-intensive fitting methods make it possible to merge mechanistic models and population data on well-studied indicator species, extending the inferences we can make about their data-limited relatives.
Historically, assessments have used data from one population or species to create ad hoc proxy values for the life-history traits of relatives, but with modern Bayesian models we can share information in a standardized, coherent way.
Advances in understanding community ecology and life-history evolution can be incorporated into these models as priors, extending statistical power even when data are sparse.
These advances offer new possibilities for the rigorous assessment and protection of populations and species that previously have suffered from policy gaps created by insufficient data.(...)

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13 juillet 2018

Fern genomes elucidate land plant evolution and cyanobacterial symbioses [Nature Plants]

Ferns are the closest sister group to all seed plants, yet little is known about their genomes other than that they are generally colossal. Here, we report on the genomes of Azolla filiculoides and Salvinia cucullata (Salviniales) and present evidence for episodic whole-genome duplication in ferns—one at the base of ‘core leptosporangiates’ and one specific to Azolla. One fern-specific gene that we identified, recently shown to confer high insect resistance, seems to have been derived from bacteria through horizontal gene transfer. Azolla coexists in a unique symbiosis with N2-fixing cyanobacteria, and we demonstrate a clear pattern of cospeciation between the two partners. Furthermore, the Azolla genome lacks genes that are common to arbuscular mycorrhizal and root nodule symbioses, and we identify several putative transporter genes specific to Azolla–cyanobacterial symbiosis. These genomic resources will help in exploring the biotechnological potential of Azolla and address fundamental questions in the evolution of plant life.

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13 juillet 2018

Spatial and temporal variation in fish community structure and diversity in the largest tropical flood‐pulse system of South‐East Asia [Ecology of Freshwater Fish]

Peng Bun Ngor, Gaël Grenouillet, Sovan Lek

The Tonle Sap River and Lake (TSRL) is South‐East Asia’s largest tropical flood pulse with a flow‐reversal system that supports one of the world’s largest freshwater fisheries. However, among the world’s tropical floodplains, the resources of the TSRL have received little ecological research. Here, we described the spatiotemporal TSRL fish diversity and community variation using daily records from 2012 to 2015 on fish abundance from six sites covering the TSRL system. We found that high fish diversity occurred in sites located in the middle of Tonle Sap Lake, and the lowest diversity was observed in the southern section. The spatial abundance distribution patterns displayed a river–lake gradient, with three fish assemblages that were clustered based on their composition similarities and were characterised by 96 indicator species.(...)

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9 juillet 2018

An inverse latitudinal gradient in speciation rate for marine fishes [Nature]

Far more species of organisms are found in the tropics than in temperate and polar regions, but the evolutionary and ecological causes of this pattern remain controversial. Tropical marine fish communities are much more diverse than cold-water fish communities found at higher latitudes, and several explanations for this latitudinal diversity gradient propose that warm reef environments serve as evolutionary ‘hotspots’ for species formation. Here we test the relationship between latitude, species richness and speciation rate across marine fishes. We assembled a time-calibrated phylogeny of all ray-finned fishes (31,526 tips, of which 11,638 had genetic data) and used this framework to describe the spatial dynamics of speciation in the marine realm.(...)

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