Document Detail

Grandparent helpers: the adaptive significance of older, postdominant helpers in the Seychelles warbler.
MedLine Citation:
PMID:  17894809     Owner:  NLM     Status:  MEDLINE    
The possibility that older, often nonreproductive, individuals may engage in kin-directed cooperative behavior has been largely overlooked in the study of cooperative breeding. Here, we describe and investigate the adaptive significance of such "grandparent" helpers in the Seychelles warbler, the first bird species in which this phenomenon has been observed. On Cousin Island, over a period of 24 years, a significant proportion (13.7%) of females, but few males (3.0%), was deposed from dominant positions. Deposed females were replaced by related females. However there was no evidence that older, senescent females were stepping aside to gain greater fitness benefits by increasing the reproductive success of their offspring, rather than breeding themselves; deposed females were not postreproductive, nor was being deposed linked to age or reproductive senescence. Of the deposed females, 68% became subordinates and helped to raise group offspring, accounting for ca. 10% of subordinates in any year. Demoted females were related (r= 0.24) to the group offspring and, consequently, could gain indirect benefits through helping. As direct benefits appeared to be limited, we suggest that indirect benefits have driven the evolution of such "grandparent helpers." This study now provides evidence for a new route to cooperative breeding in birds.
David S Richardson; Terry Burke; Jan Komdeur
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2007-09-25
Journal Detail:
Title:  Evolution; international journal of organic evolution     Volume:  61     ISSN:  0014-3820     ISO Abbreviation:  Evolution     Publication Date:  2007 Dec 
Date Detail:
Created Date:  2007-11-28     Completed Date:  2008-03-07     Revised Date:  2008-06-04    
Medline Journal Info:
Nlm Unique ID:  0373224     Medline TA:  Evolution     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2790-800     Citation Subset:  IM    
Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich, NR4 7TJ, United Kingdom.
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MeSH Terms
Adaptation, Physiological*
Age Factors
Cooperative Behavior
Nesting Behavior*
Social Dominance
Songbirds / physiology*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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