Carnicer J., Brotons L., Sol D., Jordano P. (2007) Community-based processes behind species richness gradients: Contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity. Global Ecology and Biogeography. 16: 709-719.EnllaçDoi: 10.1111/j.1466-8238.2007.00324.x
Aim: To consider the role of local colonization and extinction rates in explaining the generation and maintenance of species richness gradients at the regional scale. Location: A Mediterranean biome (oak forests, deciduous forests, shrublands, pinewoods, firwoods, alpine heathlands, crops) in Catalonia, Spain. Methods: We analysed the relative importance of direct and indirect effects of community size in explaining species richness gradients. Direct sampling effects of community size on species richness are predicted by Hubbell's neutral theory of biodiversity and biogeography. The greater the number of individuals in a locality, the greater the number of species expected by random direct sampling effects. Indirect effects are predicted by the abundance-extinction hypothesis, which states that in more productive sites increased population densities and reduced extinction rates may lead to high species richness. The study system was an altitudinal gradient of forest bird species richness. Results: We found significant support for the existence of both direct and indirect effects of community size in species richness. Thus, both the neutral and the abundance-extinction hypotheses were supported for the altitudinal species richness gradient of forest birds in Catalonia. However, these mechanisms seem to drive variation in species richness only in low-productivity areas; in high-productivity areas, species richness was uncorrelated with community size and productivity measures. Main conclusions: Our results support the existence of a geographical mosaic of community-based processes behind species richness gradients, with contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity. © 2007 The Authors © 2007 Blackwell Publishing Ltd.
Morand-Ferron J, Sol D, Lefebvre L (2007) Kleptoparasitism in birds: Brain or brawn? Anim. Behav. 74: 1725-1734
Morand-Ferron J., Sol D., Lefebvre L. (2007) Food stealing in birds: brain or brawn?. Animal Behaviour. 74: 1725-1734.EnllaçDoi: 10.1016/j.anbehav.2007.04.031
Kleptoparasitism, the stealing of food items already procured by others, is a widespread foraging strategy in animals, yet the reasons why some taxa have evolved this strategy and others have not remain unresolved. It has been hypothesized that kleptoparasitism should be more profitable, and hence have more often evolved, in lineages featuring certain characteristics, such as a large body mass, an enlarged brain or a dependence on vertebrate prey. Alternatively, the evolution of kleptoparasitism could have been facilitated in certain ecological contexts, such as open habitats or mixed-species foraging groups. Here, we test these hypotheses for the evolution of food stealing with a comparative analysis in birds, using information on 856 field reports of interspecific kleptoparasitism from all over the world. In multivariate analyses controlling for common ancestry, the probability that a family uses kleptoparasitism was positively associated with residual size of the brain, habitat openness and the presence of vertebrate prey in the diet, but showed no association with body size or participation in mixed-species foraging groups. The conclusion that kleptoparasitism is associated more closely with cognition than with aggression is further supported by the finding that kleptoparasites have a larger residual brain size than their respective hosts, while their body size is not significantly larger. By emphasizing the central role of cognitive abilities in avian kleptoparasitism, our results offer a novel perception of avian food stealing, which in the past was primarily seen in terms of 'brawn' rather than 'brains'. © 2007 The Association for the Study of Animal Behaviour.
Réale D., Reader S.M., Sol D., McDougall P.T., Dingemanse N.J. (2007) Integrating animal temperament within ecology and evolution. Biological Reviews. 82: 291-318.EnllaçDoi: 10.1111/j.1469-185X.2007.00010.x
Temperament describes the idea that individual behavioural differences are repeatable over time and across situations. This common phenomenon covers numerous traits, such as aggressiveness, avoidance of novelty, willingness to take risks, exploration, and sociality. The study of temperament is central to animal psychology, behavioural genetics, pharmacology, and animal husbandry, but relatively few studies have examined the ecology and evolution of temperament traits. This situation is surprising, given that temperament is likely to exert an important influence on many aspects of animal ecology and evolution, and that individual variation in temperament appears to be pervasive amongst animal species. Possible explanations for this neglect of temperament include a perceived irrelevance, an insufficient understanding of the link between temperament traits and fitness, and a lack of coherence in terminology with similar traits often given different names, or different traits given the same name. We propose that temperament can and should be studied within an evolutionary ecology framework and provide a terminology that could be used as a working tool for ecological studies of temperament. Our terminology includes five major temperament trait categories: shyness-boldness, exploration- avoidance, activity, sociability and aggressiveness. This terminology does not make inferences regarding underlying dispositions or psychological processes, which may have restrained ecologists and evolutionary biologists from working on these traits. We present extensive literature reviews that demonstrate that temperament traits are heritable, and linked to fitness and to several other traits of importance to ecology and evolution. Furthermore, we describe ecologically relevant measurement methods and point to several ecological and evolutionary topics that would benefit from considering temperament, such as phenotypic plasticity, conservation biology, population sampling, and invasion biology. © 2007 Cambridge Philosophical Society.
Sol D., Székely T., Liker A., Lefebvre L. (2007) Big-brained birds survive better in nature.. Proceedings. Biological sciences / The Royal Society. 274: 763-769.EnllaçDoi: 10.1098/rspb.2006.3765
Big brains are hypothesized to enhance survival of animals by facilitating flexible cognitive responses that buffer individuals against environmental stresses. Although this theory receives partial support from the finding that brain size limits the capacity of animals to behaviourally respond to environmental challenges, the hypothesis that large brains are associated with reduced mortality has never been empirically tested. Using extensive information on avian adult mortality from natural populations, we show here that species with larger brains, relative to their body size, experience lower mortality than species with smaller brains, supporting the general importance of the cognitive buffer hypothesis in the evolution of large brains.
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