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Global warming, Bergmann's rule and body mass – are they related? The chukar partridge (Alectoris chukar) case

Published online by Cambridge University Press:  01 August 2002

Yoram Yom-Tov
Affiliation:
Department of Zoology, Tel Aviv University, Tel Aviv 69978, Israel
Yoav Benjamini
Affiliation:
Department of Statistics and Operation Research, Tel Aviv University, Tel Aviv 69978, Israel
Salit Kark
Affiliation:
Department of Biological Sciences, Stanford University, Stanford, CA 94305-5020, U.S.A.
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Abstract

Using museum specimens collected in Israel during the second half of the 20th century, no support was found for the hypothesis that body mass and tarsus length of chukar partridges Alectoris chukar has changed as a result of global warming. Body mass showed fluctuations during the year, reaching a maximum in late winter and spring and a minimum in summer. Bergmann's rule predicts that in warm-blooded animals, races from warm regions will be smaller than races from colder regions, and a wider explanation states that body size is positively related to latitude. Because of its topography and varied climate, Israel provides a unique opportunity to separate partly the effect of latitude from that of ambient temperature, thus testing if Bergmann's rule is related to latitude or to climatic variables. We found that body mass (and marginally also tarsus length) declined significantly with decreasing latitude in accordance with the wider explanation of Bergmann's rule, but ambient temperature explained a much smaller fraction of the variation in body mass than latitude. These results weaken the traditional explanation to Bergmann's rule that a heat conservation mechanism causes the latitudinal size variation.

Type
Research Article
Copyright
2002 The Zoological Society of London

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