Sex-specific transgenerational effects of early developmental conditions in a passerine.
Résumé
Most studies dealing with the trade-off between offspring number and quality have overlooked the long-term consequences for the progeny. High investment in offspring number usually results in an increased competition among nest mates. The deterioration of the early developmental conditions, due to this increased competition, can impair individual quality over the long term, and subsequently affect survival and lifetime fecundity. Moreover, the consequences of the allocation rule to offspring number vs. quality can extend across generations and give raise to grandparental effects. These transgenerational trade-offs have been explored rarely. In the present study, we manipulated the breeding effort of captive zebra finches (Taeniopygia guttata) by offering them enlarged or reduced broods. Offspring reared under these conditions were allowed to breed freely in an outdoor aviary, during their entire lifespan. Second-generation fledglings whose mother was raised in enlarged broods were in lower body condition than offspring whose mother was raised in reduced broods. However, second-generation fledglings were not affected by the brood size experienced by the father. These results show that the solution of parental dilemma, whether producing a small number of high quality offspring or a large number of poor quality descendants, must take into account the long-term transgenerational effects acting on grandchildren.