Potential sources of error in parentage assessment of turbot (Scophthalmus maximus) using microsatellite loci

We evaluated essential parameters (mutation rate, null alleles and Mendelian inheritance) as well as theoretical vs. empirical power of 12 microsatellite loci for parentage determination in turbot (Scophthalmus maximus) by analysing the actual broodstock of a turbot farm and 176 full-sib families. In accordance with their high polymorphism, the theoretical expectations for parentage exclusion of these loci and of the six most polymorphic ones were always above 0.99. All parent-offspring incompatible pairs and mistaken full-sibs were, identified with both sets of 12 and 6 loci, which accords with theoretical expectations. These sets also resolved the finding of the true parents when possible. Exceptional parent-offspring incompatibilities showing a single mismatch were a consequence of nul I alleles and mutational events. The estimation of the average mutation rate for the 12 loci over 13,464 gametes analyzed was 6.7 x 10(-4). Null alleles were consistently found at a frequency close to 0.05 in the locus Sma3-129INRA, which suggests caution for pedigree tracing with this locus. The remaining 11 loci did not show evidences of null alleles after analysing a large set of appropriate family crosses. segregation in the four largest families evidenced a Mendelian model of inheritance for the loci tested. Our results suggest that this set of loci, and specially the six most polymorphic ones, constitute a suitable tool for parentage assignment and broodstock management in turbot culture. This large body of data constitutes a contribution to parentage analysis by providing actual frequency distributions of exclusionary power for different parentage relationships. (C) 2004 Elsevier B.V. All rights reserved.