Historical biogeography of cynolebiasine annual killifishes inferred from dispersal–vicariance analysis
To analyse the biogeographical events responsible for the present distribution of cynolebiasine killifishes (Teleostei: Rivulidae: Cynolebiasini), a diversified and widespread Neotropical group of annual fishes threatened with extinction. Location
South America, focusing on the main river basins draining the Brazilian Shield and adjacent zones. Methods
Phylogenetic analysis of 214 morphological characters of 102 cynolebiasine species usingtnt, in conjunction with dispersal–vicariance analysis (diva) based on the distribution of cynolebiasine species among 16 areas of endemism. Results
The basal cynolebiasine node is hypothesized to be derived from an old vicariance event occurring just after the separation of South America from Africa, when the terrains at the passive margin of the South American plate were isolated from the remaining interior areas. This would have been followed by geodispersal events caused by river-capturing episodes from the adjacent upland river basins to the coastal region. Optimal ancestral reconstructions suggest that the diversification of the tribe Cynolebiasini in north-eastern South America was first caused by vicariance events in the Paranã–Urucuia–São Francisco area, followed by dispersal from the São Francisco to the Northeastern Brazil area. The latter dispersal event occurred simultaneously in two different cynolebiasine clades, possibly as a result of a temporary connection of the São Francisco area before the uplift of the Borborema Plateau during the Miocene. The diversity of cynolebiasines inhabiting the Paraguay area is hypothesized to be derived from two processes: an older vicariance event (about 30 Ma) separating Paraguay from southern Amazonian areas (Guaporé–Xingu–Araguaia–Tocantins), and a series of more recent dispersal and vicariance events (about 15–11 Ma) caused by successive marine transgressions, which permitted alternating biotic exchange and isolation in the Paraguay, La Plata, Negro and Patos areas. Main conclusions
divaindicates there to have been a series of vicariance events congruent with tectonic episodes in South America, but the present distribution of cynolebiasines has also been shaped by a series of dispersal events. The effects of the combined action of dispersal and vicariance events were more conspicuous in the Eastern Brazil and Paraguay areas, thus generating reticulate biogeographical scenarios.
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