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Variation in offspring sex ratio of a long-lived sexually dimorphic raptor, the Eastern Imperial Eagle Aquila heliaca

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dc.contributor.author Katzner, Todd E.
dc.contributor.author Jackson, Daniel S.
dc.contributor.author Bragin, Evgeny A.
dc.contributor.author DeWoody, Andrew
dc.date.accessioned 2017-11-29T14:37:59Z
dc.date.available 2017-11-29T14:37:59Z
dc.date.issued 2014
dc.identifier.uri http://repo.kspi.kz/handle/item/532
dc.description.abstract Sex ratio theory attempts to explain observed variation in offspring sex ratio at both the population and the brood levels. In the context of low-fecundity organisms producing high-investment offspring, the drivers of adaptive variation in sex ratio are incompletely understood. For raptors that display reverse sexual dimorphism (RSD), preferential alloca-tion of resources to the putatively cheaper sex (male) may be a response to environmental, social or demographic stressors. To assess the extent of skew in offspring sex ratios and to evaluate possible dietary, environmental and demographic correlates of such skew to long-lived RSD avian species, we evaluated the offspring sex ratio of 219 chicks from 119 broods in 30 territories of Eastern Imperial Eagles Aquila heliaca across 7 years and four regions at a nature reserve in Kazakhstan. Only in one region in 1 year of our study did the offspring sex ratio differ significantly from parity (10 males : 1 female in 11 territories). Whereas offspring sex ratios were independent of dietary diversity, precipitation, tempera-ture and productivity, we found that year had a moderate effect on brood sex ratio within territories. Our results provide limited evidence of brood sex manipulation in these popu-lations of Eastern Imperial Eagles, and no mechanistic insight into predictions associated with it. Stochastic variation is likely to explain much of the fluctuation we observed in sex ratios, but our observations are also consistent with the hypothesis that sex-ratio manipula-tion may occur irregularly, in concurrence with atypical environmental or demographic conditions that fluctuate at a time scale longer than that of our 7-year study. en_US
dc.language.iso en en_US
dc.publisher Ibis en_US
dc.subject Aquila heliaca en_US
dc.subject brood sex ratio en_US
dc.subject eagle en_US
dc.subject irregular variation en_US
dc.subject stochastic variation en_US
dc.title Variation in offspring sex ratio of a long-lived sexually dimorphic raptor, the Eastern Imperial Eagle Aquila heliaca en_US
dc.type Article en_US

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    Научный журнал Ibis включен в БД Скопус.

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