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wild RBS genetic material. Once genetic baselines are established, Dexter NFHTC will have a <br />better estimate of genetic diversity of the refugium broodstock which will guide future broodstock <br />development. <br />Methods used to monitor gene pool maintenance <br />The molecular ecology program at Dexter NFHTC will initiate a long-term program of <br />genetic assessment of RBS broodfish and production fish in order to achieve our objectives <br />(Allendorf and Phelps 1981; O'Reilly and Wright 1995). The genetic character of the wild and <br />captive populations will be monitored based on the results of a genetic survey of broodstocks <br />currently held at captive propagation facilities. A suite of microsatellite markers will be used to <br />produce a genotype of each individual broodfish. This information will be used to assess and <br />monitor the refugium stocks, and identify any changes in genetic character (Allendorf and Phelps <br />1981). <br />To accomplish the objectives outlined here, Dexter NFHTC will use microsatellite <br />markers, as the most sensitive method for detecting genetic variation discovered to date. Genetic <br />markers, when used to define the status and character of a population, should be reliable, <br />reproducible, preferably codominant and highly variable. Vertebrate microsatellite loci average <br />8.7 alleles per locus (Blouin et al. 1996; Estoup et al. 1998) and are selectively neutral. <br />Microsatellites are codominant markers, so population structure, levels of heterozygosity, and <br />relatedness are easily measured (Gertsch et al. 1995; Paxton et al. 1996). Microsatellites are short <br />motifs of 2-6 bases that are repeated within a given segment of DNA. The number of repeats <br />appear to be under evolutionary constraint and rarely more than 30 (Goldstein and Pollock 1997). <br />Much controversy has been generated in recent years concerning the use of neutral genetic <br />markers, such as microsatellites, as a statistical surrogate for overall genetic variability, and the <br />assumption that heterozygosity at neutral loci may imply overall fitness (Waples 1991b; Hansson <br />23