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20 juin 2018

Global hidden harvest of freshwater fish revealed by household surveys [PNAS]

Experts have long believed that fish catches from rivers and lakes are underreported, which leads to lack of appreciation for their contribution to global food security. Rather than focusing on landing data, we backcalculated harvests using surveys of household consumption of freshwater fish. Data from 548,000 households across 42 countries reveal that freshwater catches are likely to be ∼65% higher than officially reported. These hidden harvests are concentrated in low-income countries where they represent the equivalent of the total annual animal protein consumption of 36.9 million people. Long-term underreporting of inland fisheries masks their critical role in feeding the world’s poor and complicates using catch statistics to evaluate the impact of overharvest and ecosystem degradation.

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20 juin 2018

The genomic basis of colour pattern polymorphism in the harlequin ladybird [BioRxiv]

Many animal species are comprised of discrete phenotypic forms. Understanding the genetic mechanisms generating and maintaining such phenotypic variation within species is essential to comprehending morphological diversity. A common and conspicuous example of discrete phenotypic variation in natural populations of insects is the occurrence of different colour patterns, which has motivated a rich body of ecological and genetic research. The occurrence of dark, i.e. melanic, forms, displaying discrete colour patterns, is found across multiple taxa, but the underlying genomic basis remains poorly characterized. In numerous ladybird species (Coccinellidae), the spatial arrangement of black and orange patches on adult elytra varies wildly within species, forming strikingly different complex colour patterns. In the harlequin ladybird Harmonia axyridis, more than 200 distinct colour forms have been described, which classic genetic studies suggest result from allelic variation at a single, unknown, locus. Here, we combined whole-genome sequencing, population genomics, gene expression and functional analyses, to establish that the gene pannier controls melanic pattern polymorphism in H. axyridis.(...)

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18 juin 2018

What is cumulative cultural evolution ? [Proceedings of the Royal Society B - Biological Sciences]

Keyword : animal culture, cultural evolution, cumulative culture, innovation, social learning

In recent years, the phenomenon of cumulative cultural evolution (CCE) has become the focus of major research interest in biology, psychology and anthropology. Some researchers argue that CCE is unique to humans and underlies our extraordinary evolutionary success as a species. Others claim to have found CCE in non-human species. Yet others remain sceptical that CCE is even important for explaining human behavioural diversity and complexity. These debates are hampered by multiple and often ambiguous definitions of CCE. Here, we review how researchers define, use and test CCE. We identify a core set of criteria for CCE which are both necessary and sufficient, and may be found in non-human species.(...)

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18 juin 2018

Metapopulation stability in branching river networks [PNAS]

Keywords : dendritic ecological network, portfolio effect, dispersal, streamspatially structured population

Metapopulation stability is a critical ecological property. Although ecosystem size has been considered as a fundamental driver of metapopulation stability, current theories developed in simplified landscapes may not be appropriate for complex branching ecosystems, such as rivers. Here, we show that a scale-independent characteristic of fractal river networks, branching complexity (measured as branching probability), stabilizes watershed metapopulations. We theoretically revealed that a strong association between branching complexity and metapopulation stability is a consequence of purely probabilistic processes. Furthermore, the stabilizing effect of branching complexity was consistently observed in metapopulations of four ecologically distinct riverine fishes. Hence, branching complexity may be a ubiquitous agent of metapopulation stability in branching ecosystems. The loss of such complexity may undermine resilience of metapopulations.

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15 juin 2018

Regulation between personality traits : individual social tendencies modulate whether boldness and leadership are correlated [Proceedings of the Royal Society B - Biological Sciences]

Keywords : personality, boldness, sociability, conformity, leadership, decision-making

Although consistent behavioural differences between individuals (i.e. personality variation) are now well established in animals, these differences are not always expressed when individuals interact in social groups. This can be key in important social dynamics such as leadership, which is often positively related to personality traits such as boldness. Individuals consistently differ in how social they are (their sociability), so if other axes of personality variation, such as boldness, can be suppressed during social interactions, this suppression should be stronger in more sociable individuals. We measured boldness (latency to leave a refuge when alone) and sociability (time spent with a conspecific) in three-spined sticklebacks (Gasterosteus aculeatus) and tested the boldness–leadership association in pairs of these fish.(...)

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