The effect of Parana-Paraguay river as a geographic barrier for passerines: Cyclarhis gujanensis as a study case.

KOPUCHIAN, C.; CAMPAGNA L.; CABANNE S.; TUBARO, P. L.

Lima

Congreso; IX Congreso de Ornitología Neotropical; 2011

Corbidi

The hypothesis of speciation enhanced by riverine barriers states that big rivers could represent geographic barriers for gene flow in different organisms, leading to species differentiation. This hypothesis was first proposed for the Amazon Rainforest, the area that holds the largest rivers in the Neotropics. The basin El Plata also has big rivers that could act as gene flow barriers, being in this way important in the evolution of the organisms in the region. Particularly, this was previously suggested for the Parana-Paraguay system in base of the detection of different morphological subspecies at both sides of the river, as is the case for Cyclarhis gujanensis (eastern C. g. ochreocephala and western C. g. virescens). As the first attempt to test if the Paraná River could represent a barrier to gene flow in Passerines, the objective of this study was to analyze the genetic divergence of populations of this two subspecies of C. gujanensis. We have found a deep intraspecific genetic variation in mitochondrial genes between subspecies, reaching values of 11.34% for COI and 6.6% for Cytochrome b. Parsimony analysis recovered individuals from different subspecies as two distinct monophyletic groups. A geographic structure concordant with these results would indicate that the intergradation area between virescens and ochreocephala would be eastward from the Parana channel. In this context, we discuss the possibility that the intergradation zone could match the Paraná River paleochannel, which could have been a geographic barrier for this species in the past.Cyclarhis gujanensis (eastern C. g. ochreocephala and western C. g. virescens). As the first attempt to test if the Paraná River could represent a barrier to gene flow in Passerines, the objective of this study was to analyze the genetic divergence of populations of this two subspecies of C. gujanensis. We have found a deep intraspecific genetic variation in mitochondrial genes between subspecies, reaching values of 11.34% for COI and 6.6% for Cytochrome b. Parsimony analysis recovered individuals from different subspecies as two distinct monophyletic groups. A geographic structure concordant with these results would indicate that the intergradation area between virescens and ochreocephala would be eastward from the Parana channel. In this context, we discuss the possibility that the intergradation zone could match the Paraná River paleochannel, which could have been a geographic barrier for this species in the past.