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Floodplain lakes and associated wetlands in tropical dry climates are controlled by pronounced and severe seasonal hydrologic fluctuations. We examined the plant community response to a bimodal flooding pattern in the Zapatosa Floodplain Lake Complex (ZFLC), Northern Colombia. We measured floristic and quantitative change in four sampling periods emphasizing seasonal differences in plant abundance and life-form structure. Of 79 species identified in the lake complex, 52 were used to characterize eight community types via classification and ordination procedures. Results showed that community structure does not change significantly during the flooding/receding stages. But maximum drawdown phase significantly disrupts the aquatic community structure and the exposed shorelines become colonized by ruderal terrestrial plants. Early rainfalls at the beginning of the wet season are emphasized as an important feature of plant regeneration and community development. The general strategy of the ZFLC vegetation can be framed into the flood pulse concept of river-floodplain systems. Thus, plant communities are mainly responding to disturbances and destruction events imposed by extreme water level fluctuations. Rev. Biol. Trop. 62 (3): 1073-1097. Epub 2014 September 01.

Brycon henni es una especie nativa de la cuenca del río Magdalena, Colombia, donde es fuertemente explotada, por lo cual en este trabajo se estudió la variabilidad genética y estructura poblacional en individuos provenientes de la cuenca media de los ríos Nare y Guatapé, Antioquia. Se recolectaron 195 ejemplares y se les extrajo ADN genómico total del tejido muscular y/o sanguíneo. Se evaluaron 14 cebadores para la técnica RAPD (Random Amplifyed Polimorphic DNA), siendo cuatro de ellos polimórficos, los cuales generaron 66 fragmentos diferentes (63% polimorfismo). Por medio de un análisis de varianza molecular (AMOVA), se determinó la estructuración poblacional para todos los sitios evaluados y la cuenca del río Nare ( ΦST =0.297 y ΦST =0.163, respectivamente). Las distancias genéticas de Nei mostraron que todas las poblaciones diferían entre sí y que la mayor diferenciación genética se dio para las poblaciones del río Guatapé y la quebrada El Cardal. Un test de Mantel mostró correlación entre las distancias genéticas y geográficas (ambas cuencas, r=0.431; cuenca del río Nare, r=0.377). Esto sugiere aislamiento por distancia y separación de grupos genéticos producidos por los embalses sobre los ríos Nare y Guatapé, lo cual puede tener implicaciones relevantes en la conservación de la variabilidad genética de las poblaciones naturales de esta especie en el oriente antioqueño.Genetic variability of Brycon henni (Characiformes: Characidae) in the middle basin of Nare and Guatapé rivers, Magdalena River system, Colombia. Brycon henni is a native species in Magdalena´s River basin, and because of its cultural and economic importance, is strongly overexploited. This study aimed to describe the genetic variability and population structure of this species from Nare and Guatapé rivers basins. A total of 195 individuals were collected and DNA extractions were obtained from muscle and blood tissue. Fourteen primers were evaluated with the RAPD technique, being four of them polymorphic, and produced 66 different fragments (63% polymorphism). Besides, using the molecular variance (AMOVA) analysis, the population structure was described for all sites ( ΦST=0.297, ΦST=0.163; Nare and Guatapé river basins, respectively), and suggested the importance of the migratory behaviour of the species in the genetic differentiation. Genetic distances among sampled sites showed that most of the genetic differentiation occurred between sites Guatapé and El Cardal with respect to the others. A Mantel Test demonstrated a correlation between genetic and geographic distances (r=0.431 both of the basins evaluated; r=0.377, Nare river middle basin), and suggested isolation by distance. The outcomes obtained in this study have valuable implications in species conservation and the genetic variability of natural populations of B. henni, and should be complemented with morphological analyses. Rev. Biol. Trop. 59 (1): 269-282. Epub 2011 March 01.

Floodplain lakes and associated wetlands in tropical dry climates are controlled by pronounced and severe seasonal hydrologic fluctuations. We examined the plant community response to a bimodal flooding pattern in the Zapatosa Floodplain Lake Complex (ZFLC), Northern Colombia. We measured floristic and quantitative change in four sampling periods emphasizing seasonal differences in plant abundance and life-form structure. Of 79 species identified in the lake complex, 52 were used to characterize eight community types via classification and ordination procedures. Results showed that community structure does not change significantly during the flooding/receding stages. But maximum drawdown phase significantly disrupts the aquatic community structure and the exposed shorelines become colonized by ruderal terrestrial plants. Early rainfalls at the beginning of the wet season are emphasized as an important feature of plant regeneration and community development. The general strategy of the ZFLC vegetation can be framed into the flood pulse concept of river-floodplain systems. Thus, plant communities are mainly responding to disturbances and destruction events imposed by extreme water level fluctuations. [ABSTRACT FROM AUTHOR]

Brycon henni is a native species in Magdalena's River basin, and because of its cultural and economic importance, is strongly overexploited. This study aimed to describe the genetic variability and population structure of this species from Nare and Guatapé rivers basins. A total of 195 individuals were collected and DNA extractions were obtained from muscle and blood tissue. Fourteen primers were evaluated with the RAPD technique, being four of them polymorphic, and produced 66 different fragments (63% polymorphism). Besides, using the molecular variance (AMOVA) analysis, the population structure was described for all sites (ΦST=0.297, ΦST=0.163; Nare and Guatapé river basins, respec- respectively), and suggested the importance of the migratory behaviour of the species in the genetic differentiation. Genetic distances among sampled sites showed that most of the genetic differentiation occurred between sites Guatapé and El Cardal with respect to the others. A Mantel Test demonstrated a correlation between genetic and geographic distances (r=0.431 both of the basins evaluated; r=0.377, Nare river middle basin), and suggested isolation by distance. The outcomes obtained in this study have valuable implications in species conservation and the genetic variability of natural populations of B. henni, and should be complemented with morphological analyses. Rev. Biol. Trop. 59 (1): 269-282. Epub 2011 March 01. [ABSTRACT FROM AUTHOR]