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Williamson K Gilbert L Rutstein AN Pariser EC Graves JA 《Die Naturwissenschaften》2008,95(12):1143-1148
Reproduction in opportunistically breeding bird species has traditionally been considered non-seasonal with individuals taking
advantage of favourable environmental conditions as they arise. However, some studies imply that this opportunistic breeding
may be superimposed on an underlying seasonality, which has effects on the readiness to breed when conditions are favourable.
The zebra finch (Taeniopygia guttata) is the classic opportunistic breeder and widely used as such in studies. In a series of laboratory-based breeding experiments,
we found evidence to suggest that there are seasonal differences in maternal reproductive investment in the zebra finch even
when photoperiod, temperature, relative humidity and diet were held constant. Females showed highly significant seasonal differences
in clutch size and egg mass with laying order. Clutch size showed a spring/summer peak typical of multi-brooded species in
the wild. There was also a significant increase in egg mass with laying order in all seasons except winter. This variation
in breeding parameters with season may allow females to adjust investment depending on the potential fitness returns from
a given reproductive attempt. These findings also raise a warning about interpreting results of multiple zebra finch breeding
experiments that have been carried out in different seasons. 相似文献
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E. C. Pariser L. Gilbert N. Hazon K. E. Arnold J. A. Graves 《Behavioral ecology and sociobiology》2012,66(4):519-527
Females are expected to partition resources between offspring in a context-dependent way to maximise total fitness returns
from a reproductive attempt. Female zebra finches (Taeniopygia guttata) vary the allocation of yolk androgens and antioxidants among offspring. Importantly, the balance between androgens and antioxidants
in yolks may be more important than their independent absolute amounts in terms of fitness consequences for developing young.
Therefore, we tested whether the relative allocation of these two resources in yolks varies according to either the Trivers–Willard,
positive or compensatory maternal investment hypothesis. We manipulated male attractiveness using coloured leg bands (red-banded
males appear attractive; green-banded males, unattractive) and measured yolk androgens and antioxidants in each egg, egg sex,
clutch sex ratio and female condition. While female zebra finches manipulated the balance of androgens and antioxidants within
and between clutches in response to mate attractiveness, offspring sex and their own condition, they did not do so in a way
that consistently followed any of the hypotheses. Mothers paired with unattractive males allocated a larger antioxidant/androgen
ratio to daughters than sons. This pattern was reversed when paired to an attractive male; sons received a larger antioxidant/androgen
ratio than daughters. We also found offspring sex ratio decreased with increasing female condition for unattractive males,
but not for attractive males. However, without knowing the fitness consequences of the balance of different egg constituents,
it is difficult to interpret the patterns consistently in terms of the Trivers–Willard, compensatory and positive investment
hypotheses. 相似文献
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