PROSPECTS FOR THE APPLICATION OF BASIC RESEARCH IN FISH MORPHOLOGY, PHYSIOLOGY AND GENOMICS FOR UNDERSTANDING XND INFLUENCING THE DOMESTICATION PROCESS IN AQUACULTURE SPECIES

摘要

The domestication process can be defined as the net change in traits that occur over time in wild populations exposed to the captive environment. Domestication involves both epigenetic and genetic mechanisms. Many aquaculture traits exhibit developmental plasticity in which the environmental conditions experienced by gametes and/or embryos have persistent effects on the adult phenotype. For example, embryonic temperature affects growth rate and muscle fibre number in various fish species (Johnston etal., 2003a; Johnston, 2006; Macqueen et al, 2008). Oocytes and spermatozoa contribute genetic and epigenetic factors that determine the success and outcome of early embryogenesis. Epigenetic factors include the centrosome, chromatin, and DNA methylationstate all of which directly or indirectly affect gene expression in the developing embryo. Development to the mid-blastula transition is entirely dependent on mRNAs and regulatory microRNAs transmitted in the egg yolk and sperm. Thus any divergence in hatchery conditions from those in the natural environment for either the broodstock or embryos can potentially result in significant differences in phenotype between wild and captive populations. Not only does this affect larval viability, but the phenotypes arising from developmental plasticity may themselves show different responses to selection (see Crispo, 2007 for a discussion) and are therefore an important source of evolutionary novelty during domestication. Many traits important to aquaculture and their developmental expression are subject to local adaptation between populations (Verspoor, 1997) and in such cases the source of the founder population is likely to have a very significant impact on the domestication process.