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7 mars 2017

Bumblebees can discriminate between scent-marks deposited by conspecifics [Scientif Reports]

Keywords : animal behaviour, behavioural ecology

Bumblebees secrete a substance from their tarsi wherever they land, which can be detected by conspecifics. These secretions are referred to as scent-marks, which bumblebees are able to use as social cues. Although it has been found that bumblebees can detect and associate scent-marks with rewarding or unrewarding flowers, their ability at discriminating between scent-marks from bumblebees of differing relatedness is unknown. We performed three separate experiments with bumblebees (Bombus terrestris), where they were repeatedly exposed to rewarding and unrewarding artificial flowers simultaneously.(...)

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5 mars 2017

Information Certainty Determines Social and Private Information Use in Ants [Nature]

Keywords : animal behaviour, behavioural ecology, entomology, social evolution

Decision-making in uncertain environments requires animals to evaluate, contrast and integrate various information sources to choose appropriate actions. In consensus-making groups, quorum responses are commonly used to combine private and social information, leading to both robust and flexible decisions. Here we show that in house-hunting ant colonies, individuals fine-tune the parameters of their quorum responses depending on their private knowledge : informed ants evaluating a familiar new nest rely relatively more on social than private information when the certainty of their private information is low, and vice versa. This indicates that the ants follow a highly sophisticated ‘copy-when-uncertain’ social learning strategy similar to that observed in a few vertebrate species. Using simulations, we further show that this strategy improves colony performance during emigrations and confers well-informed individuals more weight in the decision process, thus representing a novel mechanism for the emergence of leadership in collective decision-making.

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5 mars 2017

Precipitation drives global variation in natural selection [Science]

Climate change has the potential to affect the ecology and evolution of every species on Earth. Although the ecological consequences of climate change are increasingly well documented, the effects of climate on the key evolutionary process driving adaptation—natural selection—are largely unknown. We report that aspects of precipitation and potential evapotranspiration, along with the North Atlantic Oscillation, predicted variation in selection across plant and animal populations throughout many terrestrial biomes, whereas temperature explained little variation. By showing that selection was influenced by climate variation, our results indicate that climate change may cause widespread alterations in selection regimes, potentially shifting evolutionary trajectories at a global scale.

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3 mars 2017

The theory of island biogeography applies to ectomycorrhizal fungi in subalpine tree “islands” at a fine scale [Ecosphere]

Keywords : distance decay, ectomycorrhizal (ECM) fungi, Illumina MiSeq, island biogeography, next generation sequencing (NGS), Pinus albicaulis, Pinus contorta, taxa–area relationship, Yosemite National Park

The theory of island biogeography, which predicts that species richness is a function of island size and distance from the mainland, is well tested with macro-fauna and flora. Yet, in many ways, microbes are more appropriate for testing this and other ecological theories due to their small size and short generation times that translate to an ease of replication. We used a natural experimental system of isolated “host islands” to test the generality of the theory of island biogeography. Specifically, we tested whether ectomycorrhizal fungal (EMF) richness increased with tree size and decreased with distance from forest in a subalpine basin in Yosemite National Park for two congeneric pine species, Pinus albicaulis and Pinus contorta.(...)

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2 mars 2017

Using species distribution models to locate animal aggregations : a case study with Hippodamia undecimnotata (Schneider) overwintering aggregation sites [Ecological Entomology]

Eline Susset, Alexandra Magro, Jean-Louis Hemptinne

1. The protection of animals’ aggregation sites is increasingly seen as a key conservation strategy. However, to efficiently protect aggregation sites, they need to be accurately located. Species distribution models (SDMs) are an important tool in biological conservation to predict spatial distribution of species and they are used here to predict the distribution of the aggregation sites of a ladybird (Coleoptera : Coccinellidae) species.
2. Hippodamia undecimnotata forms spectacular overwintering aggregations at the same locations every year across southern and eastern Europe. In this study, an SDM was developed and its performance tested for H. undecimnotata aggregations in southwest France. Moreover, the study looked at how environmental variables correlate with ladybirds’ abundance in the aggregation sites.(...)

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