Invasive potential of common carp (*Cyprinus carpio*) and Nile tilapia (*Oreochromis niloticus*) in American freshwater systems

Nonnative fish introductions disrupt ecosystem processes and can drive native species to local extinction. Two of the most widespread, introduced species are the common carp (Cyprinus carpio) from Eurasia and the Nile tilapia (Oreochromis niloticus) from Africa. In North and South America, these introductions stem from aquaculture facilities, as well as historical introductions for recreational angling. An emergent field of ecological niche modeling provides robust predictions of the geographic potential of alien species to better understand their capacity to become established at broad scales. We used this modeling approach to produce spatially explicit predictions of the invasive potential of common carp and Nile tilapia in the Americas. Model predictions were tested using occurrence data for established populations in their native area and in the Americas. Results indicated that predictive power of niche models was high. Distributional potential of common carp in the Americas covers most temperate regions and high mountain tropical aquatic systems, whereas that of Nile tilapia is focused in the tropics and coast areas. The consequences of the potential establishment of these exotic species can be profound on native aquatic faunas, particularly on highly diverse regions such as the Amazon Basin and central Mexico. Résumé : Les introductions de poissons non indigènes perturbent les processus écosystémiques et peuvent causer l’extinction locale d’espèces indigènes. Deux des espèces les plus généralement introduites sont la carpe commune (Cyprinus carpio) d’Eurasie et le tilapia du Nil (Oreochromis niloticus) d’Afrique. En Amérique du Nord et du Sud, ces introductions proviennent des établissements d’aquaculture, ainsi que des empoissonnements passés pour la pêche sportive. Un domaine en émergence de la modélisation des niches écologiques permet de faire des prédictions robustes sur le potentiel géographique d’espèces exotiques et ainsi de comprendre leur capacité à s’établir sur de larges espaces géographiques. Cette approche de modélisation nous a permis de faire des prédictions explicites du point de vue spatial concernant le potentiel d’invasion de la carpe commune et du tilapia du Nil dans les Amériques. Nous avons testé les prédictions du modèle à l’aide de données de présence de populations établies dans leur aire d’origine et dans les Amériques. Les résultats montrent que le pouvoir prédictif des modèles de niches sont élevés. Le potentiel de répartition géographique de la carpe commune dans les Amériques englobe la plupart des régions tempérées et les écosystèmes aquatiques tropicaux de haute montagne; en revanche, le tilapia du Nil se concentre surtout dans les tropiques et les régions côtières. L’établissement potentiel des ces espèces exotiques peut avoir de graves conséquences sur les faunes aquatiques indigènes, particulièrement dans les régions de forte diversité, telles que le bassin de l’Amazone et le centre du Mexique. [Traduit par la Rédaction

Diferenciais salariais inter-regionais, interindustriais e efeitos fixos individuais: uma análise a partir de Minas Gerais

The aim of this paper is to examine whether the inter-regional and inter-industry wage differentials in Brazil persist after controlling for the non-observable workers characteristics that are fixed over time. We use data from Raismigra (Labor Ministry) to follow workers that were formally employed in Minas Gerais industry between 1999 and 2001 using a panel data approach. The main results show that the inter-regional and inter-industry wage differentials persist after controlling for individual-specific fixed effects, but lose importance.Este artigo tem como objetivo identificar se os diferenciais de salário entre os trabalhadores de diferentes regiões do Brasil e de diversos ramos industriais persistem após o controle pelas características não-observáveis destes indivíduos, que são fixas ao longo do tempo. Para atingir este objetivo, usamos a base de dados da Raismigra (MTE) para acompanhar os trabalhadores que estavam formalmente empregados na indústria de transformação de Minas Gerais entre 1999 e 2001, usando a abordagem de dados em painel. Os principais resultados obtidos indicam que os diferenciais de salário entre regiões e entre ramos de atividade persistem após o controle pela heterogeneidade dos trabalhadores, mas sua importância diminui significativamente

Restricted-Range Fishes and the Conservation of Brazilian Freshwaters

Background: Freshwaters are the most threatened ecosystems on earth. Although recent assessments provide data on global priority regions for freshwater conservation, local scale priorities remain unknown. Refining the scale of global biodiversity assessments (both at terrestrial and freshwater realms) and translating these into conservation priorities on the ground remains a major challenge to biodiversity science, and depends directly on species occurrence data of high taxonomic and geographic resolution. Brazil harbors the richest freshwater ichthyofauna in the world, but knowledge on endemic areas and conservation in Brazilian rivers is still scarce. Methodology/Principal Findings: Using data on environmental threats and revised species distribution data we detect and delineate 540 small watershed areas harboring 819 restricted-range fishes in Brazil. Many of these areas are already highly threatened, as 159 (29%) watersheds have lost more than 70% of their original vegetation cover, and only 141 (26%) show significant overlap with formally protected areas or indigenous lands. We detected 220 (40%) critical watersheds overlapping hydroelectric dams or showing both poor formal protection and widespread habitat loss; these sites harbor 344 endemic fish species that may face extinction if no conservation action is in place in the near future. Conclusions/Significance: We provide the first analysis of site-scale conservation priorities in the richest freshwater ecosystems of the globe. Our results corroborate the hypothesis that freshwater biodiversity has been neglected in former conservation assessments. The study provides a simple and straightforward method for detecting freshwater priority areas based on endemism and threat, and represents a starting point for integrating freshwater and terrestrial conservation in representative and biogeographically consistent site-scale conservation strategies, that may be scaled-up following naturally linked drainage systems. Proper management (e. g. forestry code enforcement, landscape planning) and conservation (e. g. formal protection) of the 540 watersheds detected herein will be decisive in avoiding species extinction in the richest aquatic ecosystems on the planet.Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Gordon and Betty Moore Foundatio