Potamodromous migrations in the Magdalena River basin: bimodal reproductive patterns in neotropical rivers.

Magdalena River basin potamodromous fishes have two annual reproductive seasons: the subienda in the first half of the year and the mitaca in the second. Both upstream migrations are c. 30-45 days long; after that, with the onset of the rainy season, fishes spawn and remain in the river (resident individuals) or start a downstream movement (the bajanza) to return to the Magdalena floodplain lakes (nursery, shelter and feeding grounds). Due to their particular gonad development the bocachico Prochilodus magdalenae and probably the comelón Leporinus muyscorum are physiologically able to undertake two annual basin migrations. In the presence of dams or hydropower structures, fishes are able to find alternative migration routes. Some species should be re-classified in their migratory behaviour.

Local and global spatio-temporal dynamics of HIV-1 subtype F1.

Previous studies have attempted to explore the origin of the F1 subtype, but the precise origin of the Romanian and South American F1 variants remains controversial. As the F1 subtype is the most frequent non-B variant among Europeans residing in Italy, the aim of this study was to estimate its phylogeography in order to reconstruct its origin and route of dispersion. The phylogeographical analyses, which were made using the Bayesian Markov Chain Monte Carlo approach and BEAST software, revealed two significant clades: the first included all of the Romanian strains together with a few Italian and four African isolates; the second encompassed all of the South American sequences and the large majority of Italian variants. By putting the African reference sequences into two discrete groups based on specific countries, phylogeographic analysis indicated that the F1 epidemic originated in Cameroon/Democratic Republic of Congo in the early 1940s, and was exported to South America 10 years later. Subsequently, the F1 virus spread to Angola and, from there, was exported to Romania in the early 1960s. It reached Italy in the 1970s from South America and Romania. The South American and Romanian variants of F1 have different African countries of origin and different temporal spreads. The South American variant seems to be characterized by multiple introduction events, whereas the Romanian strain probably spread as a result of a single entry. Two different pathways from South America and Romania led the F1 variant to Italy in the 1970s.