Progress on the genetics of reproductive performance in penaeid shrimp

A typical feature of penaeid shrimp larval production is that a small proportion of females with multiple spawns contribute to the production of the majority of nauplii. There is no evidence for deterioration in the condition of females and in offspring quality over consecutive spawning in a single generation. Multiple spawning capacity is genetically determined and can be a target in selection programs. Predictive phenotypic traits for selection of multiple spawners might be an important tool to increase larval production. Some of these traits already tested for their inheritance include latency to first spawn, number of spawns, fecundity, egg size, egg vitellin, egg acylglycerides, and egg proteins content, and body weight in mature females; and oocyte diameter and ovary maturity in subadult females. The present review focuses on the recent developments on the genetics of reproduction in shrimp, and on presenting what is known of some of the candidate genes involved in the multiple spawning capacities in shrimp: vitellogenin and sinus gland hormones (for which a peptide homology and phylogenetic analyses are included) and some of the enzymes involved in the biosynthetic pathway of non-peptide hormones. Finally, we present advances in the use of quantitative trait loci identification and gene expression technologies – microarrays – on the study of reproductive performance in other organisms, technologies that are expected to advance our understanding of shrimp reproduction in the future as denser genetic linkage maps and sufficient EST markers become available.