Beaver-mediated methane emission: The effects of population growth in Eurasia and the Americas

Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH(4)) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH(4) emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH(4) emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18–0.80 Tg CH(4) year(−1) (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500–42 000 km(2) of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH(4) emissions. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13280-014-0575-y) contains supplementary material, which is available to authorized users

Phylogeography of Cnesterodon decemmaculatus (Cyprinodontiformes: poeciilidae) in Southern Pampas, Argentina: ancient versus recent patterns in freshwater fishes

The Southern Pampean Area includes the southernmost limit of the Brazilian subregion and represents an interesting model to study how evolution of the landscape has affected the distribution of freshwater fishes in time and space. The hydrogeographic pattern of the region results from a combination of factors including climatic and sea level changes occurred since the Miocene and extending into the Quaternary. The hydrologic basins of this region are isolated, and have a similar ichthyological composition among them. Here we use a phylogeographic approach to infer how paleoclimatic changes affected the distribution of genetic variation in the populations of freshwater fishes. We analyzed the control region of mtDNA of Cnesterodon decemmaculatus and compared it with published data for the species Jenynsia multidentata and Corydoras paleatus in the same area. Cnesterodon decemmaculatus showed two main haplotypes with scarce divergence and wide geographical distribution within the area. The low divergence found between the Cnesterodon decemmaculatus haplotypes and the results obtained in the demographic analyses could suggest that the presence of this species in the area have a recent demographic history. These results are in contrast with the pattern reported for Jenynsia multidentata and Corydoras paleatus, where data suggest an ancient history in the area. The incongruence in the observed phylogeographical patterns could be due to the different ecological requirements of each species, and to the various responses of them to the environmental conditions resulting from geologic and paleoclimatic changes occurred in the region during the Late Quaternary.Fil: Bruno, María Cecilia. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Genética; ArgentinaFil: Mapelli, Fernando Javier. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Mar del Plata. Facultad de Ciencias Exactas y Naturales. Departamento de Biología. Laboratorio de Ecofisiología; ArgentinaFil: Casciotta, Jorge Rafael. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Almirón, Adriana Edith. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Departamento Científico Zoología Vertebrados; ArgentinaFil: Lizarralde, Marta Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; Argentin