Affichage des résultats 1001 à 1020 sur 1590 au total
Chemical risk assessment is, to date, predominantly focussed on “single species – single compound” toxicity testing of short-lived species. This approach cannot practically be used to assess all possible wildlife-pollutant combinations, and particularly falls short when assessing risk for species with life histories that do not suit laboratory experimentation. Long-lived species such as sea turtles and crocodiles are one example. In this seminar, we will present ongoing work on the exposure and accumulation of organic pollutants in sea turtles and crocodiles, and the application of computer models that integrate ecology, physiology and ecotoxicology as a basis for risk assessment for such long-lived species.
The distributions of the Trans-Himalayan large herbivores are fragmented, engendering a spatial heterogeneity in their species-richness. We capitalised on this natural-experiment situation to understand the niche dynamics of herbivores in relation to the number of sympatric species. We used the blue sheep Pseudois nayaur, a relatively widely distributed mountain ungulate, as a model species to address the issue. We selected three discrete valleys in three protected areas with almost similar environmental features but varying wild ungulate species richness, and studied the species' diet and habitat utilization in them. Habitat variables were observed in the field and microhistological faecal analysis was carried out to determine the habitat and diet widths of the animal in the three areas with different ungulate species richness. The habitat- and diet-niche widths were determined using the Shannon's H' Index. The results showed that habitat width of blue sheep has a negative relationship with the number of sympatric species. However, contrary to our expectation, there was a hump-shaped relationship between blue sheep's diet width and the sympatric species richness, with the diet width being narrower in areas of allopatry as well as in areas with greater number of sympatric species, and the widest diet spectrum in areas with moderate species richness. We suspect that the narrow diet width in allopatry is out of choice, while it is out of necessity in areas with greater number of sympatric species due to resource partitioning. We suggest that interactions with sympatric species lead to niche adjustment of mountain ungulates, and underscore the importance of including biotic interactions in species distribution models, which have often been neglected.
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Animals often show substantial variation in dispersal behaviour and resident individuals are more likely to inbreed. At least part of the variation in dispersal behaviour may be phenotype-dependent, potentially leading to non-random inbreeding with respect to a particular phenotype. Here we show that non-random inbreeding in structured populations can have important implications for estimates of the effect of inbreeding (inbreeding depression). We do this using a long-term individual-based data set for a population of Eurasian dippers (Cinclus cinclus), a bird species living exclusively along streams and rivers. Extensive pedigree data show that close inbreeding is relatively common in this species. However, inbreeding birds are not a random subsample of the population but are smaller on average. Given the significant heritability of body size, inbred individuals are smaller due to both additive genetic and inbreeding effects. Importantly, the effects of inbreeding are overestimated if additive genetic effects are not accounted for. We show how estimating the effects of inbreeding within an animal model framework removes this bias, highlighting the importance of integrating quantitative genetics and animal behaviour when measuring the effects of inbreeding in the wild.
L'ouvrage “Demographic Methods across the Tree of Life” co-édité par Rob Salguero-Gomez (Université d'Oxford) et Marlène Gamelon (LBBE) et impliquant des chercheurs du LBBE peut désormais être commandé en ligne.
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.«Telling metabolic stories to explore metabolomics data: A case study on the Yeast response to cadmium exposure» Cecilia Coimbra Klein et«Sénescence et sélection sexuelle chez les populations naturelles de vertébrés» Jean-Francois Lemaitre
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.
Deux équipes présentent des résultats ou des questions qui leurs sont propres afin de favoriser de nouvelles discussions au sein du laboratoire.