Carnicer J., Brotons L., Sol D., De Cáceres M. (2008) Random sampling, abundance-extinction dynamics and niche-filtering immigration constraints explain the generation of species richness gradients. Global Ecology and Biogeography. 17: 352-362.EnllaçDoi: 10.1111/j.1466-8238.2007.00380.x
Aim: The paradigm that species' patterns of distribution, abundance and coexistence are the result of adaptations of the species to their niches has recently been challenged by evidence that similar patterns may be generated by simple random processes. We argue here that a better understanding of macroecological patterns requires an integration of both ecological and neutral stochastic approaches. We demonstrate the utility of such an integrative approach by testing the sampling hypothesis in a species-energy relationship of forest bird species. Location: A Mediterranean biome in Catalonia, Spain. Methods: To test the sampling hypothesis we designed a metacommunity model that reproduces the stochastic sampling from a regional pool to predict local species richness variation. Four conceptually different sampling procedures were evaluated. Results: We showed that stochastic sampling processes predicted a substantial part (over 40%) of the observed variation in species richness, but left considerable variation unexplained. This remaining variation in species richness may be better understood as the result of alternative ecological processes. First, the sampling model explained more variation in species richness when the probability that a species colonises a new locality was assumed to increase with its niche width, suggesting that ecological differences between species matter when it comes to explaining macroecological patterns. Second, extinction risk was significantly lower for species inhabiting high-energy regions, suggesting that abundance-extinction processes play a significant role in shaping species richness patterns. Main conclusions: We conclude that species-energy relationships may not simply be understood as a result of either ecological or random sampling processes, but more likely as a combination of both. © 2008 The Authors Journal compilation © 2008 Blackwell Publishing Ltd.
Price T, Sol D (2008) Genetics of Colonizing Species. American Naturalist 172: S1-S3.
Sol D (2008) Revisiting the cognitive buffer hypothesis for the evolution of large brains. Biology Letters doi:10.1098/rsbl.2008.0621.
Sol D, Price TD (2008) Brain size and body size diversification in birds. American Naturalist 172: 170-177.
Hulme P.E., Bacher S., Kenis M., Klotz S., Kühn I., Minchin D., Nentwig W., Olenin S., Panov V., Pergl J., Pyšek P., Roques A., Sol D., Solarz W., Vilà M. (2008) Grasping at the routes of biological invasions: A framework for integrating pathways into policy. Journal of Applied Ecology. 45: 403-414.EnllaçDoi: 10.1111/j.1365-2664.2007.01442.x
1. Pathways describe the processes that result in the introduction of alien species from one location to another. A framework is proposed to facilitate the comparative analysis of invasion pathways by a wide range of taxa in both terrestrial and aquatic ecosystems. Comparisons with a range of data helped identify existing gaps in current knowledge of pathways and highlight the limitations of existing legislation to manage introductions of alien species. The scheme aims for universality but uses the European Union as a case study for the regulatory perspectives. 2. Alien species may arrive and enter a new region through three broad mechanisms: importation of a commodity, arrival of a transport vector, and/or natural spread from a neighbouring region where the species is itself alien. These three mechanisms result in six principal pathways: release, escape, contaminant, stowaway, corridor and unaided. 3. Alien species transported as commodities may be introduced as a deliberate release or as an escape from captivity. Many species are not intentionally transported but arrive as a contaminant of a commodity, for example pathogens and pests. Stowaways are directly associated with human transport but arrive independently of a specific commodity, for example organisms transported in ballast water, cargo and airfreight. The corridor pathway highlights the role transport infrastructures play in the introduction of alien species. The unaided pathway describes situations where natural spread results in alien species arriving into a new region from a donor region where it is also alien. 4. Vertebrate pathways tend to be characterized as deliberate releases, invertebrates as contaminants and plants as escapes. Pathogenic micro-organisms and fungi are generally introduced as contaminants of their hosts. The corridor and unaided pathways are often ignored in pathway assessments but warrant further detailed consideration. 5. Synthesis and applications. Intentional releases and escapes should be straightforward to monitor and regulate but, in practice, developing legislation has proved difficult. New introductions continue to occur through contaminant, stowaway, corridor and unaided pathways. These pathways represent special challenges for management and legislation. The present framework should enable these trends to be monitored more clearly and hopefully lead to the development of appropriate regulations or codes of practice to stem the number of future introductions. © 2007 The Authors.
Lefebvre L., Sol D. (2008) Brains, lifestyles and cognition: Are there general trends?. Brain, Behavior and Evolution. 72: 135-144.EnllaçDoi: 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. (2008) Artificial selection, naturalization, and fitness: Darwin's pigeons revisited. Biological Journal of the Linnean Society. 93: 657-665.EnllaçDoi: 10.1111/j.1095-8312.2008.00957.x
Central in biology is the view that the commonly observed association between the phenotype and the ecology of organisms is the result of the process of natural selection. There are numerous examples where the current and/or past ecological pressures in which a trait presumably arose have been demonstrated. Less well documented, however, are cases where a species that has artificially been moved from its adaptive peak is seen to return to its ancestral state when exposed to the ancient selective regime. One of the few suggested cases is that of the feral pigeon (Columba livia), the free-living descends from domesticated, artificially selected rock pigeons. Contemporary feral pigeons are significantly closer in morphology to wild rock pigeons than to their more direct domestic ancestors, suggesting that natural selection has been reconstituting their wild phenotype. Because they still preserve some characters engendered through artificial selection during their ancestral period of domesticity, notably a tarsus that is disproportionally long for a terrestrial pigeon of its size, feral pigeons provide a rare opportunity to test whether natural selection is the process behind the reconstitution of the wild phenotype. In the present study, it is shown that feral pigeons with tarsi that depart the most from the wild phenotype appear to have limitations in the use of some food resources and, as a result, experience lower survival fitness. These findings support the view that natural selection is reconstituting the wild phenotype in feral pigeons. The possibility nonetheless remains that this process will never be fully completed. © 2008 The Linnean Society of London.
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.EnllaçDoi: 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.
Sol D., Vilà M., Kühn I. (2008) The comparative analysis of historical alien introductions. Biological Invasions. 10: 1119-1129.EnllaçDoi: 10.1007/s10530-007-9189-7
The comparative analysis of past introductions has become a major approach in investigating the rules governing invasions, yet their utility to understand the invasion process is not exempt of problems. The relevance of some of these problems has not yet been fully appreciated, but it has now become clear that not taking them into account may lead to invalid conclusions. Taking examples of the plants' and birds' literature, this paper reviews these difficulties by discussing the comparative analysis of region invasibility. The difficulties include biased information toward successful introductions, confounded effects of many explanatory variables, statistical non-independence of introduction events and taxonomic levels, and inappropriate definition of the units of study. Provided that there is good information on introduction events at the appropriate spatial scale, reliable results may be obtained by using modelling techniques that control for the effects of introduction effort and species properties while dealing with spatial and phylogenetic non-independence of introduction events. In conclusion, although important progress can be made in understanding the factors behind invasibility of regions by the comparative analysis of the past introductions, this will only be possible by acknowledging the existence of biases and confounding effects in historical introductions and by using appropriate methods to deal with them. © Springer Science+Business Media B.V. 2007.
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