Mapas genéticos en acuicultura

Resumo

Genetic mapping represents a first level of the structural genomic analysis. It enables to establish a diagram of the chromosomes of a speciesshowing the relative position of anonymous and functional genetic elements,including genes. Genetic maps represent a first approach for identifying andisolating mutants or relevant genes, and lastly to ascertain their molecularand functional properties. They are essential for animal and plant produc-tion to find out the genetic basis of diseases and other productive traits. Inaddition, linkage analysis provides the framework maps which are essentialas reference for developing and completing physical maps and genomicprojects. The relationship between physical and genetic maps is not alwayslinear due to the existence of multiple cross-overs and to the variation ofchiasma probability along chromosomes. Different mapping functions havebeen proposed to solve this problem, with different assumptions about thelevel of chromosomal interference. In this context, localizing centromeresappears as a relevant task, since they reduce cross-over probability in their vicinity. In aquatic organisms, locating centromeres is accomplished throughhalf-tetrad analysis using diploid gynogenetic progenies. Additionally, thisanalysis provides a powerful tool to associate mutants or genetic markers tolinkage groups, to evaluate the existence of linkage between pairs of markers,or to obtain a detailed picture of cross-over pattern across chromosomesthrough joint segregation analysis. Knowledge of the rates of recombinationdependent on sex, chromosomal region or family has substantial practicalsignificance for experimental design and genomic analysis in the speciesof interest. In this paper, we present a review of the main methodologicalaspects involved in map construction, with particular emphasis in availabledata from aquatic organisms. In the same way, the main applications ofgenetic mapping in evolutionary and applied studies for production impro-vement of aquaculture are presented.