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13 juillet 2018

Morphological novelty emerges from pre-existing phenotypic plasticity [Nature Ecology & Evolution]

Plasticity-first evolution (PFE) posits that novel features arise when selection refines pre-existing phenotypic plasticity into an adaptive phenotype. However, PFE is controversial because few tests have been conducted in natural populations. Here we present evidence that PFE fostered the origin of an evolutionary novelty that allowed certain amphibians to invade a new niche—a distinctive carnivore morph. We compared morphology, gene expression and growth of three species of spadefoot toad tadpoles when reared on alternative diets : Scaphiopus holbrookii, which (like most frogs) never produce carnivores ; Spea multiplicata, which sometimes produce carnivores, but only through diet-induced plasticity ; and Spea bombifrons, which often produce carnivores regardless of diet. Consistent with PFE, we found diet-induced plasticity—in morphology and gene expression—in Sc. holbrookii, adaptive refinement of this plasticity in Sp. multiplicata, and further refinement of the carnivore phenotype in Sp. bombifrons. Generally, phenotypic plasticity might play a significant, if underappreciated, role in evolutionary innovation.

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13 juillet 2018

The Genome Sequences of 90 Mushrooms [Scientific Reports]

Macrofungus is defined as the fungus that grows an observable sporocarp. The sporocarps of many species are commonly called mushrooms and consumed by people all around the world as food and/or medicine. Most macrofungi belong to the divisions Basidiomycetes and Ascomycetes, which are estimated to contain more than 80,000 species in total. We report the draft genome assemblies of macrofungi (83 Basidiomycetes species and 7 Ascomycetes species) based on Illumina sequencing. The genome sizes of these species ranged from 27.4 Mb (Hygrophorus russula) to 202.2 MB (Chroogomphus rutilus). The numbers of protein-coding genes were predicted in the range of 9,511 (Hygrophorus russula) to 52,289 (Craterellus lutescens). This study provides the largest genomic dataset for macrofungi species. This resource will facilitate the artificial cultivation of edible mushrooms and the discovery of novel drug candidates.

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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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