Scorched mussels (Brachidontes spp., Bivalvia: Mytilidae) from the tropical and warm-temperate southwestern Atlantic: the role of the Amazon River in their speciation

Antitropicality is a distribution pattern where closely related taxa are separated by an intertropical latitudinal gap. Two potential examples include Brachidontes darwinianus (south eastern Brazil to Uruguay), considered by some authors as a synonym of B. exustus (Gulf of Mexico and the Caribbean), and B. solisianus, distributed along the Brazilian coast with dubious records north of the intertropical zone. Using two nuclear (18S and 28S rDNA) and one mitochondrial gene (mtDNA COI), we aimed to elucidate the phylogeographic and phylogenetic relationships among the scorched mussels present in the warm-temperate region of the southwest Atlantic. We evaluated a divergence process mediated by the tropical zone over alternative phylogeographic hypotheses. Brachidontes solisianus was closely related to B. exustus I, a species with which it exhibits an antitropical distribution. Their divergence time was approximately 2.6 Ma, consistent with the intensification of Amazon River flow. Brachidontes darwinianus, an estuarine species is shown here not to be related to this B. exustus complex. We suspect ancestral forms may have dispersed from the Caribbean to the Atlantic coast via the Trans-Amazonian seaway (Miocene). The third species, B rodriguezii is presumed to have a long history in the region with related fossil forms going back to the Miocene. Although scorched mussels are very similar in appearance, their evolutionary histories are very different, involving major historical contingencies as the formation of the Amazon River, the Panama Isthmus, and the last marine transgressio

Abundance of Culicoides (Diptera, Ceratopogonidae) species in salt marshes of the Patos Lagoon estuary, Rio Grande do Sul, Brazil: influence of climatic variables

Made available in DSpace on 2015-04-06T17:18:21Z (GMT). No. of bitstreams: 2 daiane_carrascoetal_IOC-2014.pdf: 753127 bytes, checksum: 97b54d409fc51f89325f14dfaaf4f7ad (MD5) license.txt: 1914 bytes, checksum: 7d48279ffeed55da8dfe2f8e81f3b81f (MD5) Previous issue date: 2014Universidade Federal do Rio Grande. Instituto de Oceanografia. Programa de Graduação em Oceanografia Biológica.Fundação Oswaldo Cruz. Instituto Oswaldo Cruz.Universidade Federal do Rio Grande. Instituto de Oceanografia.Marismas são áreas intermareais com vegetação dominada por gramíneas, juncos e ciperáceas, onde vários dípteros ocorrem devido à abundância de substratos para o seu desenvolvimento. Culicoides são comuns nesse tipo de habitat e são conhecidos pelo incômodo que causam ao homem e aos animais domésticos. O objetivo do trabalho foi investigar as relações existentes entre a variabilidade temporal das espécies de Culicoides nas marismas e as variáveis climáticas. As coletas foram efetuadas na Ilha da Torotama (31°53’33”S; 052°14’33”W), na Ilha da Pólvora (32°02’01’’S; 052°10’45”W) e no Molhe Oeste da Barra de Rio Grande (32°10’65”S; 052°08’52”W), de setembro de 2008 a setembro de 2010. Foram utilizadas duas armadilhas malaises instaladas em cada área. As interações entre a flutuação populacional das espécies de Culicoides e as variáveis ambientais foram investigadas através da correlação de Spearman e pela análise de correlação canônica. As três espécies coletadas no estudo foram Culicoides insignis Lutz, Culicoides venezuelensis Ortis e Misa e Culicoides caridei Brethes. C. insignis foi coletada durante todo o período amostral; C. venezuelensis esteve associada a períodos de El Niño e C. caridei de La Niña. As variáveis condicionantes na variabilidade temporal das espécies foram umidade e temperatura ambiente, precipitação e velocidade do vento.Salt marshes are intertidal areas with vegetation dominated by grasses, rushes and sedges, where many Diptera occur due to the abundance of substrates available for their development. Culicoides are common in such habitats and are known for being a nuisance to man and domestic animals. This study aimed to investigate the relationships between temporal variability in Culicoides species in salt marshes and climate variables. Samples were collected on Torotama Island (31°53’33”S; 052°14’33”W), Pólvora Island (32°02’01’’S; 052°10’45”W) and the West Breakwater of the Rio Grande (32°10’65”S; 052°08’52”W) from September 2008 to September 2010. Two malaise traps were set in each area. Interactions between the temporal fluctuations in Culicoides species populations and environmental variables were assessed using Spearman correlation and canonical correlation analysis. The three species sampled in this study were Culicoides insignis Lutz, Culicoides venezuelensis Ortis and Misa, and Culicoides caridei Brethes. C. insignis was found throughout the sampling period; C. venezuelensis was associated with El Niño periods, and C. caridei was associated with La Niña periods. The variables humidity, temperature, precipitation and wind speed influenced the species’ temporal variations