Improved empirical tests of area-heterogeneity tradeoffs

Carnicer J., Brotons L., Herrando S., Sol D. (2013) Improved empirical tests of area-heterogeneity tradeoffs. Proceedings of the National Academy of Sciences of the United States of America. 110: 0-0.
Enlace
Doi: 10.1073/pnas.1222681110

Resumen:

[No abstract available]

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Addressing a critique of the TEASI framework for invasive species risk assessment

Leung B., Roura-Pascual N., Bacher S., Heikkila J., Brotons L., Burgman M.A., Dehnen-Schmutz K., Essl F., Hulme P.E., Richardson D.M., Sol D., Vila M. (2013) Addressing a critique of the TEASI framework for invasive species risk assessment. Ecology Letters. 16: 1415-14.
Enlace
Doi: 10.1111/ele.12172

Resumen:

We address criticism that the Transport, Establishment, Abundance, Spread, Impact (TEASI) framework does not facilitate objective mapping of risk assessment methods nor defines best practice. We explain why TEASI is appropriate for mapping, despite inherent challenges, and how TEASI offers considerations for best practices, rather than suggesting one best practice. © 2013 John Wiley & Sons Ltd/CNRS.

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TEASIng apart alien species risk assessments: A framework for best practices

Leung B., Roura-Pascual N., Bacher S., Heikkilä J., Brotons L., Burgman M.A., Dehnen-Schmutz K., Essl F., Hulme P.E., Richardson D.M., Sol D., Vilà M. (2012) TEASIng apart alien species risk assessments: A framework for best practices. Ecology Letters. 15: 1475-1493.
Enlace
Doi: 10.1111/ele.12003

Resumen:

Some alien species cause substantial impacts, yet most are innocuous. Given limited resources, forecasting risks from alien species will help prioritise management. Given that risk assessment (RA) approaches vary widely, a synthesis is timely to highlight best practices. We reviewed quantitative and scoring RAs, integrating > 300 publications into arguably the most rigorous quantitative RA framework currently existing, and mapping each study onto our framework, which combines Transport, Establishment, Abundance, Spread and Impact (TEASI). Quantitative models generally measured single risk components (78% of studies), often focusing on Establishment alone (79%). Although dominant in academia, quantitative RAs are underused in policy, and should be made more accessible. Accommodating heterogeneous limited data, combining across risk components, and developing generalised RAs across species, space and time without requiring new models for each species may increase attractiveness for policy applications. Comparatively, scoring approaches covered more risk components (50% examined > 3 components), with Impact being the most common component (87%), and have been widely applied in policy (> 57%), but primarily employed expert opinion. Our framework provides guidance for questions asked, combining scores and other improvements. Our risk framework need not be completely parameterised to be informative, but instead identifies opportunities for improvement in alien species RA. © 2012 Blackwell Publishing Ltd/CNRS.

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Prominent role of invasive species in avian biodiversity loss

Clavero M., Brotons L., Pons P., Sol D. (2009) Prominent role of invasive species in avian biodiversity loss. Biological Conservation. 142: 2043-2049.
Enlace
Doi: 10.1016/j.biocon.2009.03.034

Resumen:

The rise of extinction rates associated with human activities has led to a growing interest in identifying extinction-prone taxa and extinction-promoting drivers. Previous work has identified habitat alterations and invasive species as the major drivers of recent bird extinctions. Here, we extend this work to ask how these human-driven impacts differentially affect extinction-prone taxa, and if any specific driver promotes taxonomic homogenization of avifauna. Like most previous studies, our analysis is based on global information of extinction drivers affecting threatened and extinct bird species from the IUCN Red List. Unlike previous studies, we employ a multivariate statistical framework that allows us to identify the main gradients of variation in extinction drivers. By using these gradients, we show that bird families with the highest extinction risk are primarily associated with threats posed by invasive species, once species richness and phylogeny are taken into account. As expected, the negative impact of invasive species was higher on island species, but our results also showed that it was particularly high in those species with small distribution ranges. On the other hand, mainland species and island species with large ranges tended to be affected by habitat destruction. Thus the impacts of invasive species promote the process of taxonomic homogenization among islands and between islands and continents. Consequently, introduced species may increase biotic homogenization not only directly, as generally believed, but also indirectly through their disproportional impact on endemic species imperilment. © 2009 Elsevier Ltd. All rights reserved.

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

Resumen:

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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Community-based processes behind species richness gradients: Contrasting abundance-extinction dynamics and sampling effects in areas of low and high productivity

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.
Enlace
Doi: 10.1111/j.1466-8238.2007.00324.x

Resumen:

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.

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