Full-Sib Mating Can Reduce Deleterious Effects Associated With Residual Sperm Inheritance In Gynogenotes

Fertilization of Oreochromis aureus eggs with UV-irradiated sperm from the closely related species O. niloticus, followed by diploidy restoration, produced offspring with lower embryo viability and higher skeletal deformation rates than siblings generated with sperm from a genetically distant species (Tilapia zillii). Results showed that: (a) deleterious effects due to O. niloticus sperm accu- mulate in gynogenetic fish over generations; (b) such effects are eliminated when using T. zillii sperm to fertilize eggs from gynogenetic mothers produced by full-sib matings. These results sug- gest that: (a) deleterious effects are associated with residual male DNA fragments which may be passed on to descendent offspring; (b) such fragments are significantly purged following full-sib mating. These findings suggest that biparental reproduction may play an important role in the con- trol of genome integrality by purging supernumerary chromosome fragments