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6 juillet 2018

Drosophila melanogaster establishes a species-specific mutualistic interaction with stable gut-colonizing bacteria [Plos Biology]

Subject Areas : Drosophila melanogaster, gut bacteria, bacteria, Lactobacillus, crops, ribosomal RNA, adults, Drosophila

Animals live together with diverse bacteria that can impact their biology. In Drosophila melanogaster, gut-associated bacterial communities are relatively simple in composition but also have a strong impact on host development and physiology. It is generally assumed that gut bacteria in D. melanogaster are transient and their constant ingestion with food is required to maintain their presence in the gut. Here, we identify bacterial species from wild-caught D. melanogaster that stably associate with the host independently of continuous inoculation. Moreover, we show that specific Acetobacter wild isolates can proliferate in the gut. We further demonstrate that the interaction between D. melanogaster and the wild isolated Acetobacter thailandicus is mutually beneficial and that the stability of the gut association is key to this mutualism.(...)

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6 juillet 2018

Environmental context and differences between native and invasive observed niches of Batrachochytrium salamandrivorans affect invasion risk assessments in the Western Palaearctic [Diversity and Distributions]

Keywords : biological invasion, chytrid, emerging infectious disease, partial niche filling, salamander

Aim
Identifying hosts and regions susceptible to invasion by an emerged pathogen is vital to inform early risk assessments. We here show how differences between a pathogen’s native and invasive observed niche and their underlying environments affect this process, using the recent emergence of Batrachochytrium salamandrivorans (Bsal) as a critical, empirical example.
Location
Palaearctic.
Methods
To quantify observed niches, we first gathered occurrences from the native Asian and invasive European distribution of Bsal. Through ordination in PCA‐bound environmental space, we then applied overlap tests to compare native and invasive Bsal niches with those of 56 putative Western Palaearctic host species. At last, we ensembled bivariate niche models (ESMs) for each Bsal niche to assess how differences in observed niches influenced suitability predictions.(...)

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5 juillet 2018

Community assembly and diversification in a species‐rich radiation of island weevils (Coleoptera : Cratopini) [Journal of Biogeography]

Christophe Thébaud

Aim
To test a prediction derived from island biogeographical theory that in situ speciation should make an increasingly important contribution to community assembly as islands age. This prediction is tested on estimated biogeographical histories from Mauritius (approximately 9 Myr) and Reunion (approximately 5 Myr). We additionally investigate the evolutionary dynamics of insect flight loss, as the loss of flight in island lineages can influence patterns of diversification.
Location
Mascarene Islands ; Southwest Indian Ocean.
Taxon
Weevils.
Methods
Up to five individuals of each taxonomically described species sampled within each sampling site were sequenced for the mitochondrial gene Cytochrome Oxidase II to delimit operational taxonomic units (OTUs). OTUs were further sequenced for the nuclear genes Arginine Kinase, Histone 3 and ribosomal 28s, to reconstruct the phylogenetic history of the group. Timings of colonization and in situ speciation events were estimated with beast2.(...)

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5 juillet 2018

Multilocus phylogenetics in a widespread African anuran lineage (Brevicipitidae : Breviceps) reveals patterns of diversity reflecting geoclimatic change [Journal of Biogeography]

Keywords : climate fluctuation model, cryptic species, distribution modelling, Great Escarpment, landscape barrier model, Miocene, rain frogs

Aim
To investigate models assessing the influence of geomorphology and climatic shifts on species diversification in sub‐Saharan Africa by reconstructing the pattern and timing of phylogenetic relationships of rain frogs (Brevicipitidae : Breviceps).
Location
Sub‐Saharan Africa, south of the Congo Basin.
Methods
Multilocus sequence data were generated for near complete species‐level sampling of the genus Breviceps. Phylogenetic relationships were inferred via Bayesian inference and maximum likelihood analyses on both concatenated and single‐gene datasets. Network analyses identified locus‐specific reticulate relationships among taxa. Bayesian methods were used to infer dates of divergence among Breviceps lineages, and niche modelling was used to identify possible adaptive divergence.(...)

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5 juillet 2018

The value of environmental DNA biobanking for long-term biomonitoring [Nature Ecology & Evolution - Correspondence]

To the Editor — ‘Environmental DNA’ (eDNA) metabarcoding has transformed scientists’ ability to measure the diversity of multicellular life. eDNA purified from substrates such as soil or water contains DNA fragments originating from organisms present in that environment1. Determining the sequences of a select subset of these DNA fragments (‘eDNA metabarcodes’) enables taxonomic identification of the organisms from which they derive. Recent advancements in high-throughput DNA sequencing and associated technologies have improved the effectiveness of eDNA metabarcoding. This has stimulated a rapid diversification of its application to a variety of substrates and groups of target organisms (Fig. 1).

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