Skip Navigation


Behavioral Ecology Advance Access originally published online on August 14, 2007
Behavioral Ecology 2007 18(6):1045-1050; doi:10.1093/beheco/arm075
This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Lay Summary
Right arrow All Versions of this Article:
18/6/1045    most recent
arm075v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (3)
Right arrowRequest Permissions
Google Scholar
Right arrow Articles by Bonier, F.
Right arrow Articles by Wingfield, J. C.
Right arrow Search for Related Content
PubMed
Right arrow Articles by Bonier, F.
Right arrow Articles by Wingfield, J. C.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

© The Author 2007. Published by Oxford University Press on behalf of the International Society for Behavioral Ecology. All rights reserved. For permissions, please e-mail: journals.permissions@oxfordjournals.org

Maternal corticosteroids influence primary offspring sex ratio in a free-ranging passerine bird

Frances Bonier, Paul R. Martin and John C. Wingfield

Department of Biology, University of Washington, Box 351800, Seattle, Washington 98195-1800, USA

Address correspondence to F. Bonier, who is now at Biological Sciences 0406, Virginia Tech, 2125 Derring Hall, Blacksburg, VA 24061, USA. E-mail: fb2{at}vt.edu. P.R. Martin is now at Department of Biology, Queen's University, Kingston, Ontario K7L 3N6, Canada.


  Abstract

When fitness benefits of investment in sons and daughters differ, animals are predicted to manipulate the sex ratio of their offspring. Sex ratio manipulation occurs in many taxa, but the mechanisms underlying the phenomenon in vertebrates remain largely unknown. Factors favoring skewed sex ratios, such as reduced maternal condition or food availability, also induce elevated corticosteroids. Recent experimental studies support a causal relationship between corticosteroids and sex ratio. Evidence of a natural correlation between maternal corticosteroids and offspring sex ratio has been lacking, however. Without such evidence, the importance of corticosteroids in influencing sex ratios in natural populations was unknown. We measured baseline corticosteroids in 19 free-ranging female white-crowned sparrows (Zonotrichia leucophrys) and the sex ratios of their offspring. Females with high corticosteroids produced more daughters than females with low hormone levels. We then conducted a controlled, field-based experiment investigating the effects of moderately increased maternal corticosteroids on offspring sex ratios to determine if the observed correlation reflects a causal relationship between maternal corticosteroids and offspring sex ratio. Hormone-implanted females produced more female embryos than control females. These findings provide the first evidence of a natural correlation between maternal corticosteroids and offspring sex ratios in free-ranging birds, and the first experimental evidence of a causal link between moderate increases in corticosteroids and biased primary sex ratios.

Key words: avian, corticosterone, sex ratio, Trivers-Willard model, Zonotrichia leucophrys.

Received 14 September 2006; revised 2 July 2007; accepted 18 July 2007.


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?




Disclaimer:
Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.