Population structure of guppies in north-eastern Venezuela, the area of putative incipient speciation
Magdalena Herdegen1*, Heather J Alexander2,3, Wiesław Babik1, Jesús Mavárez4,5, Felix Breden6 and Jacek Radwan7
Background: Geographic barriers to gene flow and divergence among populations in sexual traits are two
important causes of genetic isolation which may lead to speciation. Genetic isolation may be facilitated if these two mechanisms act synergistically. The guppy from the Cumaná region (within the Cariaco drainage) of eastern Venezuela has been previously described as a case of incipient speciation driven by sexual selection, significantly
differentiated in sexual colouration and body shape from the common guppy, Poecilia reticulata. The latter occurs
widely in northern Venezuela, including the south-eastern side of Cordillera de la Costa, where it inhabits streams belonging to the San Juan drainage. Here, we present molecular and morphological analyses of Differentiation among guppy populations in the Cariaco and San Juan drainages. Our analyses are based on a 953 bp long mtDNA fragment, a set of 15 microsatellites (519 fish from 20 populations), and four phenotypic traits.