Study of hybrid and backcross abalone populations uncovers trait separation and their thermal resistance capacity

Hybridization and backcrossing are classical breeding methods that can effectively improve the genetic characteristics of organisms through heterosis. The hybrid abalone (Haliotis discus hannai ♀ × H. fulgens ♂, DF) and backcrosses are cultured on a large scale due to their high survival rates under heat stress in summer. The thermal resistance of purebreds, hybrid F1 and backcross populations were evaluated through Arrhenius break temperature (ABT) of cardiac performance in this study. The results showed that the hybrid F1 had the best thermal resistance, and the ABT gradually decreased with the increase in recurring number. In addition, a growth experiment of DD × DF (H. discus hannai ♀ × DF ♂) populations showed that DD × DF-Y (presence of black spots in the visceral mass of DD × DF) grew faster than DD × DF-N (absence of spots in the visceral mass of DD × DF) (p < 0.05), but the ABT of DD × DF-Y was lower than that of DD × DF-N (p < 0.05). The results suggest that the presence or absence of black spots in the visceral mass could be used as a breeding trait for the thermal resistance and growth of backcross abalone. This study provides basic data for further study of the response of abalone to heat stress for the healthy and sustainable development of the abalone industry.