Plant & Animal Genomes XV Conference

January 13-17, 2007
Town & Country Convention Center
San Diego, CA

A Mass Spawn Of Lion-Paw Scallop (Nodipecten subnodosus): Genetic Contribution Of Spawners To The Progeny And Allelic Inheritance

Jessica L Petersen¹ , Ana M Ibarra² , Bernie P May¹

¹  Genomic Variation Laboratory, University of California Davis, One Shields Ave, Davis, CA 95616 USA

²  Centro de Investigaciones Biológicas del Noroeste, LaPaz, B.C.S. Mexico

Aquaculture of the lion-paw scallop along the Baja California Peninsula, Mexico, is increasing. Most spat production for aquaculture is performed through induced mass spawns, where millions of offspring are produced by only a few spawners. As functional hermaphrodites, self-fertilization is possible, and unless all spawners contribute equally to the progeny, the effective population size may be reduced. Inbreeding could decrease the fitness of the hatchery stock and impact natural populations if introgression were to occur. Microsatellite genotyping of six parents and 374, seven-month old mass spawn progeny revealed that 51 percent of the progeny were full siblings, with four of fifteen possible out-cross families unrepresented. Each spawner contributed between 1.4 and 38.9 percent to the progeny. The number of offspring per spawner, and family distribution was significantly different than that expected if the progeny represented an equal and random association of gametes. A total of seven null alleles were identified within five of the loci examined. Analyses of allelic inheritance in the two largest families revealed random segregation at four variable loci of one parent in one cross but non-random segregation for the same individual in the other cross. It is unknown whether these results reflect pre/post-zygotic selection or a maternal/paternal effect. These data illustrate the need to improve current spawning procedures to maximize the number of individuals contributing to the spawn. If mass spawning continues, the possibility of culturing sterile, triploid scallops should be considered as a means to eliminate any opportunity for out-crossing with natural populations.