Biologia reprodutiva de Vanellus chilensis (Aves: Charadriidae) : por que reproduzir em grupo?

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

It has been recently demonstrated that females can reduce their egg investment without incurring costs onto the developing embryos. This happens when females breed in the presence of helpers-at-the-nest that compensate for the egg nutrient reduction by bringing more food for the chicks. Using the southern lapwing (Vanellus chilensis) as the study subject, this dissertation tested the effects of the presence of extra individuals on maternal investment. Hence, to achieve this objective the study evaluated 4 hypotheses: (1) clutch size is larger in nests of groups than in nests of pairs, (2) the incubation period is reduced in group with extra individuals, (3) egg quality is reduced by the presence of helpers in the breeding unit, and (4) chicks of mothers with helpers have lower body mass index (BMI). The flexible meta-analysis was adapted to estimate the average effect size for the association between group size and maternal investment. The results of the meta-analysis indicate a negative association between the duration of the incubation period and group size. A negative association between egg volume and group size was also observed. A small negative association between egg nutritional investment variables (yolk, protein and lipid mass) and group size was observed, however these were not significant. There was no association between clutch size, chick BMI and group size. The result of the metaanalysis shows a general association between the reduction in maternal investments and the presence of extra individuals, without affecting the offspring. This study supports the maternal investment reduction hypothesis in cooperatively breeding species.

ASSUNTO(S)

cuidado parental cooperative breeding ecologia ovos nutrients nutrientes investimento maternal reprodução cooperativa maternal investment parental care eggs

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