INTERSPECIFIC GENETIC MAP AND BREEDING PROGRAM FOR TILAPIA

¹ Department of Animal Science, University of California, One Shields Avenue, Davis, CA 95616-8521 USA

² Department of Aquaculture, A.R.O., The Volcani Center, Bet-Dagan, Israel 50250

³ Department of Fisheries and Wildlife Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061-0321 USA

⁴ Through June 30, 1999: Department of Food Engineering and Biotechnology Technion University, Haifa 32000, Israel

⁵ Dept of Aquaculture, Faculty of Fisheries, Kasetsart University, Chatuchak, Bangkok 10900 Thailand

A program aiming at breeding new, synthetic populations of tilapia specifically adapted to temperate climates and saline environments was designed to exploit the ease of producing interspecific hybrids among tilapias. Systematic interspecific crossing of tilapia species was carried out to produce a synthetic stock of tilapia (an `artificial center of origin,' or ACO) upon which to select broodstock adapted to colder temperatures and higher salinity. The ACO involved four tilapiine species: Oreochromis niloticus (wild-type and red strains), O. aureus, O. mossambicus, and Sarotherodon galilaeus. Starting with parental species, 2-way crosses (2WC; F₁ and F₂), 3-way crosses (3WC) and 4-way crosses (4WC) were produced. The ACO contains wide genetic diversity and opportunities for genes to recombine and interact with genes originating from other species in the gene pool, combinations and interactions which are impossible in any of the pure species. Two linkage maps have been completed from one [Om x (Oa x ROn] 3WC family. The map of the Om female has 62 markers (13 microsatellites, 49 AFLPs) divided into 14 linkage groups covering 514 cM. The male was an F₁ hybrid (Oa x ROn), and therefore has many more heterozygous loci than the pure species female. Because of this, the male map has 214 markers (60 microsatellites, 154 AFLPs) divided into 24 linkage groups covering 1642 cM.