Do group size and laying order influence maternal deposition of XXXX in smooth-billed ani eggs?

@entity1573 @entity251 @entity342
The avian egg contains maternal hormones that affect behavior, growth, morphology, and offspring survival. Evidence to date suggests that patterns of yolk @entity342 deposition could provide females with a means to manipulate sibling competition and, thereby, increase their fitness. We examined yolk @entity251 (T) concentrations in eggs of the smooth-billed ani (Crotophaga ani) to understand patterns of @entity342 deposition in eggs of this plural-breeding joint-nesting cooperatively breeding species. We tested the hatching asynchrony adjustment hypothesis, which states that increases in yolk @entity342 levels over the laying sequence function to mitigate the disadvantage of being a later-hatched @entity1573 in species without adaptive brood reduction. We also investigated the effect of group size on yolk T deposition to test the hypothesis that females in multi-female groups could give a competitive edge to their own chicks by depositing higher T levels in their eggs. Predictions of the hatching asynchrony adjustment hypothesis were supported in both single- and multi-female groups as yolk @entity251 levels increased from early- to late-laid eggs. This suggests that ani females can influence nestling competition and @entity1573 survival by within-clutch differential T allocation. Unexpectedly, we did not observe an effect of group size on yolk T deposition. Yolk @entity251 concentrations may not be a mere reflection of a female's hormonal status as female plasma circulating levels of T did not vary in the same direction as yolk T levels. Results of this study therefore support the idea that females may adaptively manipulate @entity1573 behavior through hormonal deposition in eggs.
