Advances in the molecular analysis of fish population structure

The characteristics of high population and species biodiversity, taken toge ther with the major anthropogenic threats arising from exploitation, introd uctions and habitat alterations, have ensured that fishes have received maj or attention from molecular biologists in the study of wild populations. Fo remost among the various challenges has been the development of techniques to estimate population discreteness and associated patterns of dispersal an d gene flow, so-called stock structure analysis. Here, we review some recen t developments in molecular technology, especially microsatellite analysis, and consider critically how such markers can be employed to estimate genet ic differentiation in species exhibiting high mobility in open waters. Comp arisons are made between microsatellites and other genetic markers (protein and DNA) in their ability to detect population structuring. Particular emp hasis is placed on the need to design sampling programmes that rake account of aspects of the biology of the species under study, and the scale and na ture of sample collection. Recent novel applications of PCR-based technolog y in the analysis of population structure are considered including the dete ction of microgeographic differentiation, the analysis of historical fish p opulations using recovered DNA, and the molecular characterization of allel ic variants among populations in relation to function.