Movimento e estruturação genética de duas espécies de peixes de um riacho costeiro de Mata Atlântica, Marica RJ

Abstract

Understand how a dispersion and a population structure are interrelated and the issue of common interest among ecologists and population geneticists. In this work, there is no behavior of movement of Astyanax hastatus and Geophagus brasiliensis in Rio Ubatiba, RJ, influencing the genetic structuring of the populations, so that G. brasiliensis, due to its territorialistic behavior, less movement accomplishment, presents a lesser general Context and some degree of genetic structuring, while A. hastatus, because it is a more active species, presents a greater gene flow along the river, thus presenting a panmitic population. To test this hypothesis we evaluated the intensity of the movement of each species using the capture, marking and recapture (CMR) technique of the fish, as well as determining the genetic structuring level for both species through a mitochondrial marker (D-loop). For CMR, despite the low number of recaptured tagged individuals, the results show that A. hastatus moves more and at distances greater than G. brasiliensis, thus possessing a greater amount of movement and a larger area of life. A. hastatus presented greater genetic diversity in relation to G. brasiliensis, this result is associated to a greater dispersion capacity and other characteristics of the biology of A. hastatus, such as pelagic spawning and broader distribution. The genetic structure verified through the Fst index suggests that A. hastatus represents a panmítica unit, whereas, G. brasiliensis presents genetic structuring between the most upstream point and the others, being attributed to the distance isolation, due to the characteristics as territorialist behavior , parental care and restricted movement. In the Ubatiba River, regardless of any inherent pattern in the history of basin colonization, the biological characteristics of the species (sedentary habit and non sedentary habit) are suggested as determining factors of the levels of diversity and genetic structuring observed for these species