ABSTRACT
Since the late 1960s, allozyrne polyrnorphisms have been extensively used as genetic markers to address various population and aquaculture genetics problems in a wide range of organisms (Murphy et al. 1996), and they continue to be widely used today. However, beginning in the late 1980s, methods for the detection and analysis of nuclear DNA genetic markers have revolutionized genetic and population studies in many biological disciplines. These newer markers often overcame the more severe limitations of allozyrne markers. For instance, the need for relatively large fresh or freshly frozen tissue samples meant that non-lethal sampling was generally not possible. Also, the comparatively low level of polyrnorphisms revealed by individual allozyrne loci and the absolute number of loci available for analysis prevented many questions from being answered or even explored. For the past decade, DNA-based molecular techniques and variations of already established techniques have been developed at a rapid rate and these techniques are becoming widely adopted in many research areas. This in tum has led to rapid advances in analytical and statistical tools to address the new and fortuitous problem of dealing with the large amount of information generated by these DNA-based techniques (Luikart and England 1999).
