Acorns containing deeper plumule survive better: how white oaks counter embryo excision by rodents
Article first published online: 11 DEC 2013
© 2013 The Authors. Ecology and Evolution published by John Wiley & Sons Ltd.
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Ecology and Evolution
Volume 4, Issue 1, pages 59–66, January 2014
How to Cite
Ecology and Evolution 2014; 4(1):59–66.
- Issue published online: 3 JAN 2014
- Article first published online: 11 DEC 2013
- Manuscript Accepted: 25 OCT 2013
- Manuscript Revised: 22 OCT 2013
- Manuscript Received: 20 JUN 2013
- Natural Science Foundation of China. Grant Numbers: 31172101, 41203018
- Program for New Century Excellent Talents in University. Grant Number: NCET-12-0693
- Acorn germination;
- embryo depth;
- embryo excision;
- white oak.
Several squirrel species excise the embryo of acorns of most white oak species to arrest germination for long-term storage. However, it is not clear how these acorns counter embryo excision and survive in the arms race of coevolution. In this study, we simulated the embryo excision behavior of squirrels by removing 4 mm of cotyledon from the apical end of white oak acorns differing in embryo depths to investigate the effects of embryo excision on acorn germination and seedling performance of white oak species. The embryo depth in the cotyledons was significantly different among white oak acorns, with Quercus mongolica containing the embryo most deeply in the acorns. We found that artificial embryo excision significantly decreased acorn germination rates of Quercus variabilis, Quercus acutissima, Quercus aliena, Quercus aliena var. acutiserrata, Quercus serrata. var. brevipetiolata but not Q. mongolica. Artificial embryo excision exerted significant negative impacts on seedling performance of all oak species except Quercus aliena. Our study demonstrates the role of embryo depth of acorns in countering embryo excision by squirrels and may explain the fact that squirrels do not perform embryo excision in acorns of Q. mongolica with deeper embryos. This apparent adaptation of acorns sheds light on the coevolutionary dynamics between oaks and their seed predators.