Characterization of triploid hybrid groupers from interspecies hybridization (Epinephelus coioides♀ ×Epinephelus lanceolatus♂)

Abstract

Interspecies hybridization is widely used in aquaculture as a beneficial strategy. Diploid and triploid hybrids have been detected from the interspecies hybridization of Epinephelus coioides ♀ 9 Epinephelus lanceolatus ♂. This is the first report of triploidization through hybridization in grouper. Confirmation has been obtained through flow cytometry, karyotyping and erythrocyte nuclei measurement. The chromosome numbers of E. coioides, E. lanceolatus, diploid hybrid grouper are 48 and triploid hybrid grouper are 72. Measurements of erythrocyte nuclei indicate that triploid fish have a larger nuclear surface than the diploid groupers, and the average ratio of triploid to diploid surface area is 1.59. During the first 1.5 years, triploid hybrid groupers grow faster than diploid hybrid groupers or either parent species. The average growth rate of triploid hybrids is 1.61 times greater than that of diploid hybrids at 6 months of age and 1.43 times greater at 18 months of age. The triploid hybrid groupers are inferior in gonadal development, with no primary-growth-stage oocytes appearing in the gonads at 18 months of age.Morphological studies indicate that triploid hybrid groupers have distinctive differences in snout length, eye diameter, body trunk shape, and tail shape development compared with diploid hybrid groupers. Triploid hybrid groupers have an advantage in growth ability, and artificial breeding of triploid groupers might be of great potential use in the grouper aquaculture industry.

A review of grouper (Family Serranidae: Subfamily Epinephelinae) aquaculture from a sustainability science perspective

“…However, it was not clear whether gonadal development in diploid E. coioides × E. lanceolatus hybrids could reach sexual maturity and produce viable offspring (Huang et al . ). Attempts in Indonesia to back cross hybrid grouper with one of their parental species have reportedly been unsuccessful (Suko Ismi, pers.…”

“…Recently, Huang et al . () found that between 7% and 15% of hybrid ( E. coioides × E. lanceolatus ) groupers are triploid. The triploid fish grew 1.6 times as fast as the diploid hybrids to 6 months of age, and 1.4 times as fast to 18 months of age (Huang et al .…”

Comparison of Gonadal Development in Diploid and Triploid Hybrid Groupers, Epinephelus coioides♀ × Epinephelus lanceolatus♂

“…In our previous study, we showed that hybrid progenies (referred to as orange‐giant groupers) could be successfully produced via the crossing of female E. coioides and male E. lanceolatus . Both diploid and triploid hybrid groupers were isolated through flow cytometry detection, and karyotyping and erythrocyte nuclei measurement (Huang et al ). Compared with their parental species, we found that the diploid and triploid hybrid groupers exhibited an advantage in growth performance, indicating that the established hybrid groupers present great potential for application in the grouper aquaculture industry (Huang et al ).…”

“…Both diploid and triploid hybrid groupers were isolated through flow cytometry detection, and karyotyping and erythrocyte nuclei measurement (Huang et al ). Compared with their parental species, we found that the diploid and triploid hybrid groupers exhibited an advantage in growth performance, indicating that the established hybrid groupers present great potential for application in the grouper aquaculture industry (Huang et al ). However, the reproductive function of hybrids generated through interspecies hybridization may be severely affected.…”

“…However, the reproductive function of hybrids generated through interspecies hybridization may be severely affected. The gonadal development of triploid hybrids appeared to be impeded, with no primary‐growth‐stage oocytes being observed in the gonads of 18‐mo‐old triploid hybrids, while the gonads of diploid hybrids and their parental species at the same age were in the primary‐growth oocyte stage (Huang et al ). As we examined only the gonadal status of 18‐mo‐old hybrids, whether the gonads of diploid and triploid hybrids undergo normal development with age is still unclear.…”