From genetics to chemistry to herbivory: Interactions between North American porcupines and trembling aspens.
Diner, Brandee*,1, Berteaux, Dominique2, 3, Lindroth, Rick4, Fyles, Jim 1, 1 McGill University, Macdonald Campus, Ste-Anne-de-Bellevue, Québec, Canada2 Canada Research Chair in Conservation of Northern Ecosystems, Rimouski, Québec, Canada3 Centre d’Etudes Nordiques, Rimouski, Québec, Canada4 University of Wisconsin, Madison, WI, USA
ABSTRACT- Plant-herbivore interactions play a significant role in the study of all ecosystems. Co-evolutionary theory suggests that plant defenses have evolved due to herbivore pressure and that herbivores have the potential to shape the genetic composition of their food resources. We used the interactions between North American porcupines Erethizon dorsatum and trembling aspens Populus tremuloides as a study system to investigate an important assumption of this theory, namely, that herbivores must be selecting food sources based on traits that are under genetic control. We confirmed that porcupines exhibit intra-species food selection through visual examination of porcupine scars left on tree bark and through controlled feeding experiments. We linked selection to the genetic composition of the aspen stand by showing that two phenolic glycosides (tremulacin and salicortin), both under genetic control, are the chemical variables that most influence feeding choices by porcupines. This work therefore creates an important link in the relationship between plant chemistry, genetics, and mammalian herbivory and raises the notion that porcupines may act as selective agents on the genetic composition of the aspen stand.
Key words: mammalian herbivory, phenolic glycosides, chemical defense, clone
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