Abstract

Pacific abalone (Haliotis discus hannai) and Californian red abalone (Haliotis rufescens) are easily distinguished by their shell and epipodial characteristics. A few individuals of H. rufescens were discovered to have epipodial coloration similar to that of H. discus hannai suggesting that they may have been hybrids of the two species, because hybridization of these species has been informally reported from local hatcheries. The present Study uses molecular genetic methods to determine whether the rarely colored variants represented hybrids between the two species. Two hundred RAPD primers were tested with PCR on two DNA pools of eight individuals of each species. Primers that showed different amplification profiles between species were tested on 27 randomly sampled individuals of each species to check the existence of polymorphisms. Two primers differentiate both species. Primer 356 amplified an approximately 450 bp and 460 bp specifies-DNA fragments in H. discus hannai that were not present in red abalone, whereas primer 368 amplified a 750 bp, 850 bp, 860 bp, and 1,190 bp specific-DNA fragments in H. rufescens that were not present in H. discus hannai. The amplification pattern of the DNA of individuals with ambiguous morphology for both primers was characteristic of red abalone. The results strongly suggested that the specimens with unusual epipodial coloration were not hybrids, but rather, phenotypic variants of H. rufescens. Future studies should focus on the cause of the variation of epipodium color in H. rufescens, which could be either genetic polymorphism or phenotypic plasticity.