Phenotypic trait ofCrassostrea hongkongensis♀×C. angulata♂ hybrids in southern China

Abstract

The Hong Kong oyster (Crassostrea hongkongensis) and the Portuguese oyster (Crassostrea angulata) are important aquaculture species in southern China. To understand the potential feasibility of hybridization between the two species, two-bytwo factorial cross-experiments were conducted in Shenzhen (Guangdong province). An asymmetry in fertilization was revealed: C. hongkongensis eggs could be fertilized by C. angulata sperm, but the reciprocal cross was not possible. The fertilization and hatching success in the C. hongkongensis females 9 C. angulata males (HA) cross was lower than the two intraspecific crosses. Moreover, hybrid larvae had a slower growth rate than those from parental progenies due to genome incompatibility. However, the size of the spat and adult growth were greater than those of the two parental progeny, with obvious heterosis during the grow-out stage. The survival advantage of hybrids was examined at all times. The surprising finding was that all hybrids were completely fertile, meaning they could produce normal and functional gametes. Genetic analysis by molecular markers was applied to confirm that the HA spat were true hybrids. Our results revealed that the interspecific hybridization between C. hongkongensis and C. angulata is completely successful in one direction. Furthermore, hybrids are viable, fast growing and completely fertile, which provides a promising method for the genetic improvement of oysters as a new aquaculture stock in southern China.

A comparative study of the survival, growth and gonad development of the diploid and triploid Hong Kong oyster, Crassostrea hongkongensis (Lam & Morton 2003)

“…There are several recent papers addressing various questions regarding cross‐breeding of Hong Kong oyster with other oysters (Zhang et al . , ; Huo, Wang, Yan & Gaffney ; Zhang, Zhang, Li, Su, Guan, Xiao, Li & Yu ; Zhang, Zhang, Li, Wang, Yan & Yu ,b; Zhang, Zhang, Li, Xiao, Xiang, Wang, Yan & Yu ). However, in spite of its high economic value, there is limited information available about triploidy in C .…”

Growth performance and biochemical composition of the oysters Crassostrea sikamea , Crassostrea angulata and their hybrids in southern China

“…Positive heterosis in both growth and survival in hybrid oysters has only been reported in few cases. Such heterosis in hybrids has been observed in crosses between oysters C. hongkongensis × C. angulata (Zhang et al., ).…”

“…Similarly naturally occurring fertile hybrid between C. gigas and C. sikamea has also been observed (Camara et al., ). Previous reports (Yao et al., ; Zhang et al., ) indicate that hybrids in the Crassostrea genus were completely fertile, with the exception C. hongkongensis and C. gigas crosses (Zhang et al., ). These findings suggest that genomic introgression between different oyster species is possible.…”

“…Viability of the aquaculture animal is a very important performance trait which is primarily affected by environmental conditions (Zhang et al., ). In this study, hybrids spats initially showed lower growth and higher mortality as compared to the progenies from intraspecific crosses.…”

“…Among molluscs, such hybridization studies have been mainly focused on oysters, scallops and abalones. Some interspecific hybrids have found commercial utility due to their improved growth rate, survival rate, food conversion and stress resistance (Cruz & Gallardo‐Escárate, ; Wang et al., ; Zhang et al., ). Xu, Li, Wang and Zhang () studied the larval stage of the interspecific hybrids between C. angulata and C. sikamea .…”