Development and characteristics of artificial interspecific hybridization between Tridacna maxima and T. crocea

Interspecific hybridization has demonstrated its effectiveness in genetic modification, with the goal of developing novel species that inherits beneficial characteristics from each parent. In the present study, a 2 × 2 factorial hybridization was conducted for the first time, creating four groups: T. maxima ♀ × T. maxima ♂ (MM), T. crocea ♀ × T. crocea ♂ (CC), T. maxima ♀ × T. crocea ♂(MC), and T. crocea ♀ × T. maxima ♂ (CM). The fertilization and hatching rates of the MC and CM hybrids were similar to those of the intraspecific crosses, achieving satisfactory levels. Compared to CC, MC and CM hybrids also displayed notable growth advantages in shell length and survival rate during juvenile period. Notably, the MC and CM hybrids exhibited substantially faster growth rates compared to the parental giant clams after larval stage, with the highest survival rate (24.47 ± 1.51 %) in these groups at one year old. Moreover, the shell length of the hybrid juveniles significantly exceeded that of the progeny of the two parental species from day 30–360. The shell shape of hybrid offspring was mainly influenced by the maternal parent, whereas the mantle color in MC offspring was influenced by both parents. Like the progenies of pure parents, both hybrids developed normal gonads and were capable of gamete production. All these results indicated that hybrid offspring displayed higher survival rates, faster growth rates, and enhanced mantle colors compared to their parental giant clams. As a result, these hybrids offer great promise for the aquarium trade and aquaculture sectors. • Interspecific hybridization between Tridacna maxima and Tridacna crocea was successfully induced in captivity. • Capillary electrophoresis successfully confirmed the hybrids. • The hybrid offspring show considerable heterosis in terms of growth, survival and mantle color. • The hybrids had delayed gonadal development, but gamete morphology and function were normal.