Sex troie adult
An increase in transgene frequency is often assumed to be unlikely because transgenic organisms typically have some viability disadvantage.Reduced viability is assumed to be common because transgenic individuals are best viewed as macromutants that lack any history of selection that could reduce negative fitness effects.Widespread interest in producing transgenic organisms is balanced by concern over ecological hazards, such as species extinction if such organisms were to be released into nature.An ecological risk associated with the introduction of a transgenic organism is that the transgene, though rare, can spread in a natural population.The range of values also encompassed the particular fitness component estimates that we obtained.We conducted a 2 × 2 factorial experiment to assess the early viability of offspring produced from crosses involving transgenic and wild-type medaka parents (15).Such risks should be evaluated with each new transgenic animal before release.Although production of transgenic organisms offers great agricultural potential, introduction of genetically modified organisms into natural populations could result in ecological hazards, such as species extinction (1–3).
We categorized these differences into four fitness components: () sexual selection (mating advantages).
Such risk has been suggested to pose little environmental threat because transgenic organisms are evolutionary novelties that would have reduced viability (4, 5).
However, transgenic organisms may also possess an advantage in some aspect of reproduction that may increase their success in nature.
We found that, regardless of protocol, large males obtained a 4-fold mating advantage (16).
Such size-related mating advantages have been demonstrated in a variety of fish species; they can result from mate competition or mate choice or both (12).
Individuals were readily bred in the lab, were easily cultured, and attained sexual maturity in about two months.