Document Detail

Seasonal change in irradiance: a zeitgeber for circannual rhythms in ground squirrels.
MedLine Citation:
PMID:  1673890     Owner:  NLM     Status:  MEDLINE    
1. Zeitgebers for circannual rhythms have been elusive. Demonstration that an external factor is a zeitgeber requires proof of a phase-shift that endures for several years. 2. The California ground squirrel (Spermophilus beecheyi) is an ideal subject. Many features of behavior have circannual rhythms of which change in mass is the easiest to measure. The squirrels thrive in captivity for up to 10 years. The squirrels were kept in individual cages in an air conditioned room, fed lab chow ad lib, and weighed twice a month. They were exposed to a 6-month phase shift of (a) length of day (b) seasonal change in temperature, (c) both, (d) seasonal cycle of irradiance. 3. The squirrels maintained circannual rhythms for up to 9 years. Entrainment was evident only by squirrels exposed to seasonal change in irradiance.
D E Davis
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Comparative biochemistry and physiology. A, Comparative physiology     Volume:  98     ISSN:  0300-9629     ISO Abbreviation:  Comp Biochem Physiol A Comp Physiol     Publication Date:  1991  
Date Detail:
Created Date:  1991-06-07     Completed Date:  1991-06-07     Revised Date:  2008-10-30    
Medline Journal Info:
Nlm Unique ID:  1276312     Medline TA:  Comp Biochem Physiol A Comp Physiol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  241-3     Citation Subset:  IM    
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MeSH Terms
Sciuridae / physiology*

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