Genetic variability of the Amazon River prawn Macrobrachium amazonicum (Decapoda, Caridea, Palaemonidae)

The freshwater prawn Macrobrachium amazonicum is widely distributed in South America, and occupies habitats with a wide range of salinities. Several investigations have revealed the existence of wide intraspecific variability among different populations, although the understanding of this variability is still fragmentary and incomplete. We compared and characterized inland and coastal populations of M. amazonicum from Brazil, using molecular data (16S and COI mtDNA) to describe the degree of variability, structure, and relationships among them. Genetic divergence rates among populations showed variability at the intraspecific level. All the analyses evidenced significant genetic divergence among populations, structuring them in three groups: I-inland waters of the Amazonian Hydrographic Region (HR); II-Parana/Paraguay HR; and III-coastal systems of northern and northeastern Brazil. Phylogenetic reconstructions revealed that the populations form a single monophyletic clade, which supports their characterization as a single species. Clade I was a sister clade of that formed by clades II and III, which were themselves sister clades. Populations from Sertaozinho/Miguelopolis and Avare, introduced into the state of Sao Paulo, may have originated from natural populations in the states of Mato Grosso do Sul and Para, respectively. Geographical isolation probably contributed to the observed variation, and if this isolation continues. M. amazonicum may undergo speciation within its broad geographical distribution. The sequences obtained here can be used as name-tags for population identification, and the DNA barcodes are useful to identify the origin of specimens used in different freshwater-prawn cultures or introduced populations of unknown origin.

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[CNPq 134460/07-3]

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[471794/2006-6]

Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)[473050/2007-2]

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[02/08178-9]

Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)[05/50651-1]

CAPES/(DAAD) Deutscher Akademischer Austausch Dienst, Germany[315/09]

CAPES[02630/09-5]