Document Type

Article

Publication Title

Biological Journal of the Linnean Society

Publication Date

2020

Keywords

house wren, maculation, oxidative stress, protoporphyrin, sexual selection, Troglodytes aedon

Abstract

Differences in avian eggshell pigmentation could be an honest signal of female quality that males use to inform their nestling provisioning effort. We investigated whether among-individual variation in protoporphyrin-based eggshell pigmentation in house wrens (Troglodytes aedon) reflects female fitness-associated traits and whether males use that information. Females laying lighter clutches were older and larger than females laying darker clutches. Nestlings hatching from lighter clutches had greater size-corrected mass on post-hatch day 11, a measure that strongly predicts survival and recruitment to the breeding population. To test whether male provisioning effort responds to clutch pigmentation, we used a reciprocal clutch cross-fostering design, swapping dark with light clutches and light with dark; in controls, we swapped light with light clutches and dark with dark. Shortly before hatching, clutches were returned to their original nest to avoid confounding effects of nestling quality on male provisioning. Contrary to the sexual selection hypothesis, clutch pigmentation had no effect on male provisioning. Males were probably able to observe eggshell pigmentation and thus had information about female quality, but they did not use this information to modulate their nestling provisioning. This may be because of constraints on species-specific reproductive opportunities, or because variation in eggshell protoporphyrin serves other functions.

Funding Source

This research was supported by grants from the National Institutes of Health (R15HD076308 to S.K.S. and C.F.T; R03AG063314 to N.T.M.; R15AR070505 to A.D.V.-M.), the American Ornithological Society (to K.E.H.), Sigma Xi Scientific Research Honor Society (to K.E.H.), the Beta Lambda Chapter of the Phi Sigma Honor Society (to K.E.H.) and a Summer Faculty Fellowship from Illinois State University (to S.K.S.).

Comments

First published in Biological Journal of the Linnean Society: https://doi.org/10.1093/biolinnean/blaa002

DOI

10.1093/biolinnean/blaa002

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