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Kolliker Mathias; Heeb Philipp; Werner Isabelle; Mateman A. C.; Lessells C. M.; Richner Heinz 《Behavioral ecology》1999,10(1):68-72
Sex allocation theory predicts that the allocation of resourcesto male and
female function should depend on potential fitnessgain realized through
investment in either sex. In the greattit (Parus major), a
monogamous passerine bird, male resourceholdingpotential (RHP) and
fertilization success both depend on malebody size (e.g., tarsus length) and
plumage traits (e.g., breaststripe size). It is predicted that the proportion
of sons ina brood should increase both with male body size and plumage
traits,assuming that these traits show a fatheroffspring correlation.
Thiswas confirmed in our study: the proportion of sons in the brood
increasedsignificantly with male tarsus length and also, though not
significantly,with the size of the breast stripe. A sex ratio bias in
relationto male tarsus length was already present in the eggs because(1) the
bias was similar among broods with and without mortalitybefore the nestlings'
sex was determined, and (2) the bias remainedsignificant when the proportion
of sons in the clutch was conservativelyestimated, assuming that differential
mortality before sex determinationcaused the bias. The bias was still present
among recruits.The assumption of a fatheroffspring correlation was
confirmedfor tarsus length. Given that both RHP and fertilization successof
male great tits depend on body size, and size of father andoffspring is
correlated, the sex ratio bias may be adaptive. 相似文献
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Neuenschwander Samuel; Brinkhof Martin W. G.; Kolliker Mathias; Richner Heinz 《Behavioral ecology》2003,14(4):457-462
Evolutionary theory of parent-offspring conflict explains beggingdisplays of nestling birds as selfish attempts to influenceparental food allocation. Models predict that this conflictmay be resolved by honest signaling of offspring need to parents,or by competition among nestmates, leading to escalated beggingscrambles. Although the former type of models has been qualitativelysupported by experimental studies, the potential for a beggingcomponent driven by scramble competition cannot be excludedby the evidence. In a brood-size manipulation experiment withgreat tits, Parus major, we explored the scramble componentin the begging activity of great tit nestlings by investigatingthe mechanisms of sibling competition in relation to brood size.While under full parental compensation, the feeding rate pernestling will remain constant over all brood sizes for bothtypes of models; the scramble begging models alone predict anincrease in begging intensity with brood size, if begging costsdo not arise exclusively through predation. Great tit parentsadjusted feeding rates to brood size and fed nestlings at similarrates and with similar prey sizes in all three brood-size categories.Despite full parental compensation, the begging and food solicitationactivities increased with experimental brood size, whereas nestlingbody condition deteriorated. These findings support a scramblecomponent in begging and suggest that the competition-inducedcosts of food solicitation behavior play an important role inthe evolution of parent-offspring communication. 相似文献
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