Inbreeding depression and maternal effects on early performance of Pacific abalone

Effects of inbreeding and maternity on early performance were studied in the Pacific abalone Haliotis discus hannai using two sets of 2 x 2 factorial crosses involving sister-brother mating. Parents from three full-sib families produced from two wild abalone populations (Japan and China) were used for the study. Metamorphic success and larval growth in four inbred (F = 0.25) and four outbred families were evaluated to 20 d postfertilization. In set I, inbreeding depression was 8.65% for metamorphic success, and - 1.06, 3.25, and 4.98% for larval size at days 6, 10, and 20, respectively. In set II, inbreeding depression was 39.3% for metamorphic success, and 1.92, 4.99, and 3.37% for size at days 6, 10, and 20, respectively. Additionally, there were significant maternal effects on metamorphosis and larval size on day 6 (P < 0.01) in set I, which became insignificant at days 10 and 20. Maternal effects were absent in set II. The results of this study suggest that inbreeding at F = 0.25 significantly affects larval growth and greatly reduces metamorphic success in the Pacific abalone.