Fire Drives Transcontinental Variation in Tree Birch Defense against Browsing by Snowshoe Hares

Fire has been the dominant disturbance in boreal America since the Pleistocene, resulting in a spatial mosaic in which the most fire occurs in the continental northwest. Spatial variation in snowshoe hare (Lepus americanus) density reflects the fire mosaic. Because fire initiates secondary forest su...

Full description

Saved in:

Bibliographic Details
Published in:	The American naturalist Vol. 174; no. 1; pp. 13 - 23
Main Authors:	Bryant, John P., Clausen, Thomas P., Swihart, Robert K., Landhäusser, Simon M., Stevens, Michael T., Hawkins, Christopher D. B., Carrière, Suzanne, Kirilenko, Andrei P., Veitch, Alasdair M., Popko, Richard A., Cleland, David T., Williams, Joseph H., Jakubas, Walter J., Carlson, Michael R., Bodony, Karin Lehmkuhl, Cebrian, Merben, Paragi, Thomas F., Picone, Peter M., Moore, Jeffrey E., Packee, Edmond C., Malone, Thomas
Format:	Journal Article
Language:	English
Published:	Chicago, IL The University of Chicago Press 01-07-2009 University of Chicago Press University of Chicago, acting through its Press
Subjects:	Animal and plant ecology Animal behavior Animal, plant and microbial ecology Animals Betula - genetics Betula - metabolism Betula neoalaskana Betula papyrifera Biological and medical sciences Biological Evolution Browsing Ecosystem Fires Forest & brush fires Forest and land fires Forest fires Fundamental and applied biological sciences. Psychology General aspects Geographical variation Hardwood trees Hares Hares - genetics Hares - metabolism Lepus americanus Mammals Mosaic Phytopathology. Animal pests. Plant and forest protection Plant glands Resins Seedlings Toxins Toxins, Biological Trees Triterpenes - metabolism Weather damages. Fires USA, Wisconsin USA, Alaska tree birch forest fire snowshoe hare selection mosaic antibrowsing defense Browsing Lepus americanus Woody plant Lagomorpha Vertebrata Mammalia Dicotyledones Angiospermae Tree Defense mechanism Spermatophyta Forest fire Betula Betulaceae
Online Access:	Get full text
Tags:	Add Tag No Tags, Be the first to tag this record!

Description
Summary:	Fire has been the dominant disturbance in boreal America since the Pleistocene, resulting in a spatial mosaic in which the most fire occurs in the continental northwest. Spatial variation in snowshoe hare (Lepus americanus) density reflects the fire mosaic. Because fire initiates secondary forest succession, a fire mosaic creates variation in the abundance of early successional plants that snowshoe hares eat in winter, leading to geographic variation in hare density. We hypothesize that fire is the template for a geographic mosaic of natural selection: where fire is greatest and hares are most abundant, hare browsing has most strongly selected juvenile‐phase woody plants for defense. We tested the hypothesis at multiple spatial scales using Alaska birch (Betula neoalaskana) and white birch (Betula papyrifera). We also examined five alternative hypotheses for geographic variation in antibrowsing defense. The fire‐hare‐defense hypothesis was supported at transcontinental, regional, and local scales; alternative hypotheses were rejected. Our results link transcontinental variation in species interactions to an abiotic environmental driver, fire. Intakes of defense toxins by Alaskan hares exceed those by Wisconsin hares, suggesting that the proposed selection mosaic may coincide with a geographic mosaic of coevolution.
Bibliography:	ObjectType-Article-1 SourceType-Scholarly Journals-1 ObjectType-Feature-2 content type line 23
ISSN:	0003-0147 1537-5323
DOI:	10.1086/599304