ABSTRACT
Populational genetic differentiations in marine fishes have been demonstrated using nuclear and mitochondrial DNA markers and allozymes. In spite of the important role of fish in the marine environment, where they are important members of the community acting on its structure through processes of predation, competition, and territoriality, little is known about the genetic evolutionary processes leading to such diversity. Understanding the processes of speciation is one of the aspects derived from the genetic studies in marine fishes, which only have begun to be investigated more thoroughly. In a general way, the majority of marine fish hybrids are extremely rare in nature and are probably the result of unusual circumstances. Primitive and common karyotypes, composed only by acrocentric elements, allow for determining and even quantifying rearrangements in perciform karyotypes. Among all fish orders, the Perciformes constitute a potentially useful model in understanding the genetic structure of marine populations, as well as the establishment of their evolutionary patterns.
