Artificial interspecific hybridization of two giant clams, Tridacna squamosa and Tridacna crocea, in the south China sea

Interspecific hybridization has been used as an important tool for genetic manipulation in mollusks, with the aim to produce a new species with desirable traits from both the parental species. A two by two factorial cross between sympatric giant clam species, the fluted giant clam, Tridacna squamosa (S) and the boring clam, Tridacan crocea (C), yielded hybrids that were fast growing (characteristic of the S) and had brightly colored mantles (characteristic of C). Reciprocal hybrids (SC and CS) were obtained by the acceptable level of fertilization and hatching rate compared to these of two parental species, and the survival rate of the hybrids was significantly higher than that of the parental species. Yearling hybrids exhibited fully developed gonads and normal gametogenesis when sexually mature. Relative to CC, CS and SC also showed significant growth advantages in shell length and wet weight. The shell morphology of the hybrids was mainly dictated by maternal effect, while mantle coloration was dictated by paternal effect for SC progeny and parental effect for CS progeny. Our results revealed that reciprocal hybrids exhibited great growth heterosis and survival advantage (compared to C), as well as better mantle colors. Thus, these hybrids have great potential for application in the aquarium market and aquaculture industries across the globe.