Genetic variability of the Amazon River prawn Macrobrachium amazonicum

structure 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 ex-istence of wide intraspecific variability among different popu-lations, 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 de-gree 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 Hydrographi