Survival performance at early developmental stages was significantly lower in diploid and triploid hybrids than that of the control S.aurata groups with triploid hybrids having aparticularly high larval mortality. At early developmental stages the reciprocal hybrid female P.major×male S.aurata had a survival similar to that of its direct hybrid female S.aurata×male P.major(our unpublished data).Poor survival at the early developmental stages has been observed in experiments with intergeneric hybridization in other sparidae species of commercial interest, as well as in salmonids .furthermore,reported complete mortality by the yolk-sac larval stage in the reciprocal hybrid between female P.major(our unpublished data). Poor survival at the early developmental stages has been observed in experiments with intergeneric hybridization in other sparidae species of commercial interest, as well as in salmonids. Furthermore, reported complete mortality by the yolk-sac larval stage in the reciprocal hybrid between female P.pagrus and male S.aurata, and considered this cross as genetically lethal. This is not surprising as our intergeneric hybridization experiments with other sparidae species were also not consistently successful. For instance in the hybrid between female S.aurata and male Acanthopagrus bifasciatus, we observed total mortality of offspring beyond day 30 after hatching despite a high fertilization rate at the beginning of egg incubation. On the other hand, kraljevic and dulcic observed relatively low mortality rates from hatching to day 30 among intergeneric reciprocal hybrids obtained by artificial insemination of P.major and Dentex dentex. In our growout trials, the overall survival rates tended to be the highest for S.aurata, lower for P.major, almost intermediate in hybrid female S.aurata×male P.major(hybrid A) and the lowest for triploid hybrids. The lowest mortality rates(0%) in juvenile stages of S.aurata have also been indicated in hybridization experiments of paspatis et al.
At the same time survival observed in juvenile stages(experiment 3/94, part I) of hybrid female P.major×male S.aurata(hybrid B) was similar to that of the parental species in juvenile stages Under our rearing conditions the cause of fish mortality is likely to be multifaceted, although a disease diagnosis showed that a marine ciliate parasite Cryptocaryon irritans ()made a major contribution to the mortality variation.
Survival performance at early developmental stages was significantly lower in diploid and triploid hybrids than that of the control S.aurata groups with triploid hybrids having aparticularly high larval mortality. At early developmental stages the reciprocal hybrid female P.major×male S.aurata had a survival similar to that of its direct hybrid female S.aurata×male P.major(our unpublished data).Poor survival at the early developmental stages has been observed in experiments with intergeneric hybridization in other sparidae species of commercial interest, as well as in salmonids .furthermore,reported complete mortality by the yolk-sac larval stage in the reciprocal hybrid between female P.major(our unpublished data). Poor survival at the early developmental stages has been observed in experiments with intergeneric hybridization in other sparidae species of commercial interest, as well as in salmonids. Furthermore, reported complete mortality by the yolk-sac larval stage in the reciprocal hybrid between female P.pagrus and male S.aurata, and considered this cross as genetically lethal. This is not surprising as our intergeneric hybridization experiments with other sparidae species were also not consistently successful. For instance in the hybrid between female S.aurata and male Acanthopagrus bifasciatus, we observed total mortality of offspring beyond day 30 after hatching despite a high fertilization rate at the beginning of egg incubation. On the other hand, kraljevic and dulcic observed relatively low mortality rates from hatching to day 30 among intergeneric reciprocal hybrids obtained by artificial insemination of P.major and Dentex dentex. In our growout trials, the overall survival rates tended to be the highest for S.aurata, lower for P.major, almost intermediate in hybrid female S.aurata×male P.major(hybrid A) and the lowest for triploid hybrids. The lowest mortality rates(0%) in juvenile stages of S.aurata have also been indicated in hybridization experiments of paspatis et al.
At the same time survival observed in juvenile stages(experiment 3/94, part I) of hybrid female P.major×male S.aurata(hybrid B) was similar to that of the parental species in juvenile stages Under our rearing conditions the cause of fish mortality is likely to be multifaceted, although a disease diagnosis showed that a marine ciliate parasite Cryptocaryon irritans ()made a major contribution to the mortality variation.
การแปล กรุณารอสักครู่..