Ducatez S., Sayol F., Sol D., Lefebvre L. (2018) Are Urban Vertebrates City Specialists, Artificial Habitat Exploiters, or Environmental Generalists?. Integrative and comparative biology. 58: 929-938.LinkDoi: 10.1093/icb/icy101
Although urbanization is a major threat to biodiversity, some species are able to thrive in cities. This might be because they have specific adaptations to urban conditions, because they are able to cope with artificial habitats in general or because they are generalists that can live in a wide range of conditions. We use the latest version of the IUCN database to distinguish these possibilities in 25,985 species of the four classes of terrestrial vertebrates with the help of phylogenetically controlled methods. We first compare species occurrence in cities with that of the five other artificial habitats recognized by the IUCN and use principal components analyses to ask which of these most resembles cities. We then test whether urban species have a wider habitat breadth than species occurring in other, non-urban, artificial habitats, as well as species that occur only in natural habitats. Our results suggest that the proportion of terrestrial vertebrates that occur in urban environments is small and that, among the species that do occur in cities, the great majority also occur in other artificial habitats. Our data also show that the presence of terrestrial vertebrates in urban habitats is skewed in favor of habitat generalists. In birds and mammals, species occurrence in urban areas is most similar to that of rural gardens, while in reptiles and amphibians, urban areas most resemble pasture and arable land. Our study suggests that cities are likely not unique, as is often thought, and may resemble other types of artificial environments, which urban exploiters can adapt to because of their wide habitat breadth.
Sayol F., Lefebvre L., Sol D. (2016) Relative brain size and its relation with the associative pallium in birds. Brain, Behavior and Evolution. 87: 69-77.LinkDoi: 10.1159/000444670
Despite growing interest in the evolution of enlarged brains, the biological significance of brain size variation remains controversial. Much of the controversy is over the extent to which brain structures have evolved independently of each other (mosaic evolution) or in a coordinated way (concerted evolution). If larger brains have evolved by the increase of different brain regions in different species, it follows that comparisons of the whole brain might be biologically meaningless. Such an argument has been used to criticize comparative attempts to explain the existing variation in whole-brain size among species. Here, we show that pallium areas associated with domain-general cognition represent a large fraction of the entire brain, are disproportionally larger in large-brained birds and accurately predict variation in the whole brain when allometric effects are appropriately accounted for. While this does not question the importance of mosaic evolution, it suggests that examining specialized, small areas of the brain is not very helpful for understanding why some birds have evolved such large brains. Instead, the size of the whole brain reflects consistent variation in associative pallium areas and hence is functionally meaningful for comparative analyses. © 2016 S. Karger AG, Basel.
Sol D., Sayol F., Ducatez S., Lefebvre L. (2016) The life-history basis of behavioural innovations. Philosophical Transactions of the Royal Society B: Biological Sciences. 371: 0-0.LinkDoi: 10.1098/rstb.2015.0187
The evolutionary origin of innovativeness remains puzzling because innovating means responding to novel or unusual problems and hence is unlikely to be selected by itself. A plausible alternative is considering innovativeness as a co-opted product of traits that have evolved for other functions yet together predispose individuals to solve problems by adopting novel behaviours. However, this raises the question of why these adaptations should evolve together in an animal. Here, we develop the argument that the adaptations enabling animals to innovate evolve together because they are jointly part of a life-history strategy for coping with environmental changes. In support of this claim, we present comparative evidence showing that in birds, (i) innovative propensity is linked to life histories that prioritize future over current reproduction, (ii) the link is in part explained by differences in brain size, and (iii) innovative propensity and life-history traits may evolve together in generalist species that frequently expose themselves to novel or unusual conditions. Combined with previous evidence, these findings suggest that innovativeness is not a specialized adaptation but more likely part of a broader general adaptive system to cope with changes in the environment. © 2016 The Author(s) Published by the Royal Society. All rights reserved.
Lefebvre L., Reader S.M., Sol D. (2013) Innovating innovation rate and its relationship with brains, ecology and general intelligence. Brain, Behavior and Evolution. 81: 143-145.LinkDoi: 10.1159/000348485
[No abstract available]
Lefebvre L., Sol D. (2008) Brains, lifestyles and cognition: Are there general trends?. Brain, Behavior and Evolution. 72: 135-144.LinkDoi: 10.1159/000151473
Comparative and experimental approaches to cognition in different animal taxa suggest some degree of convergent evolution. Similar cognitive trends associated with similar lifestyles (sociality, generalism, new habitats) are seen in taxa that are phylogenetically distant and possess remarkably different brains. Many cognitive measures show positive intercorrelations at the inter-individual and inter-taxon level, suggesting some degree of general intelligence. Ecological principles like the unpredictability of resources in space and time may drive different types of cognition (e.g., social and non-social) in the same direction. Taxa that rank high on comparative counts of cognition in the field are usually the ones that succeed well in experimental tests, with the exception of avian imitation. From apes to birds, fish and beetles, a few common principles appear to have influenced the evolution of brains and cognition in widely divergent taxa. Copyright © 2008 S. Karger AG.
Sol D., Bacher S., Reader S.M., Lefebvre L. (2008) Brain size predicts the success of mammal species introduced into novel environments. American Naturalist. 172: 0-0.LinkDoi: 10.1086/588304
Large brains, relative to body size, can confer advantages to individuals in the form of behavioral flexibility. Such enhanced behavioral flexibility is predicted to carry fitness benefits to individuals facing novel or altered environmental conditions, a theory known as the brain size-environmental change hypothesis. Here, we provide the first empirical link between brain size and survival in novel environments in mammals, the largest-brained animals on Earth. Using a global database documenting the outcome of more than 400 introduction events, we show that mammal species with larger brains, relative to their body mass, tend to be more successful than species with smaller brains at establishing themselves when introduced to novel environments, when both taxonomic and regional autocorrelations are accounted for. This finding is robust to the effect of other factors known to influence establishment success, including introduction effort and habitat generalism. Our results replicate similar findings in birds, increasing the generality of evidence for the idea that enlarged brains can provide a survival advantage in novel environments. © 2008 by The University of Chicago.
Morand-Ferron J., Sol D., Lefebvre L. (2007) Food stealing in birds: brain or brawn?. Animal Behaviour. 74: 1725-1734.LinkDoi: 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.
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.LinkDoi: 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.
Lefebvre L., Marino L., Sol D., Lemieux-Lefebvre S., Arshad S. (2006) Erratum: Large brains and lengthened life history periods in odontocetes (Brain, Behavior and Evolution (2006) 68, (218-228)). Brain, Behavior and Evolution. 68: 228-0.LinkDoi: 10.1159/000096902
Lefebvre L., Marino L., Sol D., Lemieux-Lefebvre S., Arshad S. (2006) Large brains and lengthened life history periods in odontocetes. Brain, Behavior and Evolution. 68: 218-228.LinkDoi: 10.1159/000094359
Previous work on primates and birds suggests that large brains require longer periods of juvenile growth, leading to reproductive constraints due to delayed maturation. However, longevity is often extended in large-brained species, possibly compensating for delayed maturation. We examined the relationship between brain size and life history periods in cetaceans, a large-brained mammalian order that has been largely ignored. We looked at males and females of twenty-five species of Odontocetes, using independent contrasts and multiple regressions to disentangle possible phylogenetic effects and inter-correlations among life history traits. We corrected all variables for body size allometry and separated life span into adult and juvenile periods. For females and both sexes combined, gestation, time to sexual maturity, time as an adult and life span were all positively associated with residual brain size in simple regressions; in multiple regressions, maximum life span and time as an adult were the best predictors of brain size. Males showed few significant trends. Our results suggest that brain size has co-evolved with extended life history periods in Odontocetes, as it has in primates and birds, and that a lengthened adult period could have been an important component of encephalization in cetaceans. Copyright © 2006 S. Karger AG.
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