Competition, niche opportunities and the successful invasion of natural habitats

Vall-llosera, M., Llimona, F., de Cáceres, M., Sales, S., Sol, D. (2016) Competition, niche opportunities and the successful invasion of natural habitats. Biological Invasions. : 1-12.
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Doi: 10.1007/s10530-016-1246-7

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A framework for estimating niche metrics using the resemblance between qualitative resources

de Cáceres M., Sol D., Lapiedra O., Legendre P. (2011) A framework for estimating niche metrics using the resemblance between qualitative resources. Oikos. 120: 1341-1350.
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Doi: 10.1111/j.1600-0706.2011.19679.x

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Despite the central importance of the niche concept for the ecological theory, current methods to quantify the species niche from qualitative resources, such as food or habitat types, remain insufficiently developed. Classically, information theory and diversity measures have formed the toolbox used for calculating resource niche metrics on species preference data for a set of qualitative resources. We provide a comprehensive framework that extends these classical approaches by incorporating the resemblance between resources into the calculation of resource niche metrics. This does not only allow estimation of the niche centre, breadth, overlap and displacement with greater accuracy, but also makes the estimates less influenced by the way the resources are subdivided. In addition, all niche metrics can be calculated while taking into account the variation in resource availability, and confidence intervals can be obtained by bootstrapping. We illustrate the utility of the framework with an analysis of dietary preferences in feral pigeons Columba livia. © 2011 The Authors. Oikos © 2011 Nordic Society Oikos.

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Random sampling, abundance-extinction dynamics and niche-filtering immigration constraints explain the generation of species richness gradients

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.
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Doi: 10.1111/j.1466-8238.2007.00380.x

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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.

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