Behavioral archives link the chemistry and clonal structure of trembling aspen to the food choice of North American porcupine

Abstract

Understanding the links among plant genotype, plant chemistry, and food selection by vertebrate herbivores is critical to assess the role of herbivores in the evolution of plant secondary chemistry. Some specialized vertebrate herbivores have been shown to select plants differentially according to plant genotype, but examples from generalists, which constitute the vast majority of vertebrate herbivores, are few, especially in natural conditions. We examined the relationship between the North American porcupine (Erethizon dorsatum), a generalist mammalian herbivore, and clonal trembling aspen (Populus tremuloides), a preferred food source of porcupines. We determined preference for certain aspen trees through visual examination of porcupine climbing scars left on tree bark, and through a controlled feeding experiment. We used genetic and biochemical analyses to link the behavioral archives (climbing scars) left by porcupines on aspen trunks to the clonal structure and chemical composition of trees. We show that two phenolic glycosides (tremulacin and salicortin), which are under a high degree of genetic control and thus vary in concentration across clones, are the chemical variables that most influence (deter) feeding choices by porcupines. Using behavioral archives left by a wild herbivore on a natural stand of plants thus allowed us to demonstrate that a generalist vertebrate herbivore can choose plants according to their clonal structure and genetically based chemical composition. Our results contribute to extending previous findings obtained with generalist herbivores studied in controlled conditions, and with specialist herbivores studied in the field.

Herbivory enhances positive effects of plant genotypic diversity

“…Both voles and deer selectively attacked different O. biennis genotypes in our study (Fig. 4), supporting a growing body of literature showing that generalist vertebrates can feed selectively among genotypes within a species, including voles (Pusenius et al 2002), beavers (Bailey et al 2004), hares (Laitinen et al 2004), porcupine (Diner et al 2009), deer (Duncan et al 2001) and moose (Jia et al 1997). More importantly, selective feeding in our study differentially influenced genotype fitness and resulted in natural selection for plant traits.…”

Genotypic Differences and Prior Defoliation Affect Re-Growth and Phytochemistry after Coppicing in Populus tremuloides

“…This increased pressure is likely driven by mammals rather than by insects because mammals can take advantage of the very young sprouts' short stature during a brief window of opportunity. Previous studies have shown phenolic glycosides to reduce the preference or performance of several mammals (Wooley et al, 2008;Diner et al, 2009) and insects (Hwang and Lindroth, 1998;Lindroth, 2001, 2004;Donaldson and Lindroth, 2007). Fewer studies have revealed antiherbivore properties of condensed tannins (Ayres et al, 1997), but see Donaldson and Lindroth (2004) and Bailey et al (2004).…”

“…Insect herbivores include outbreak species such as the forest tent caterpillar, gypsy moth, and large aspen tortrix (Mattson et al, 1991), while mammalian herbivores include beaver, deer, elk, hare, moose, and porcupine (Perala, 1990;Diner et al, 2009). Many studies have shown antiherbivore properties of phenolic glycosides against both insects Lindroth, 2001, 2004;Donaldson and Lindroth, 2007) and mammals (Wooley et al, 2008;Diner et al, 2009).…”

“…Evidence supporting the anti-herbivore properties of condensed tannins is more limited (Ayres et al, 1997). In aspen, some studies have shown that condensed tannins confer resistance (Bailey et al, 2004;Donaldson and Lindroth, 2004), while many others have not (e.g., Lindroth, 1997, 1998;Wooley et al, 2008;Diner et al, 2009).…”

Influence of leaf chemistry on dietary choice and habitat quality of koala (Phascolarctos cinereus) populations in southwest Queensland

“…It is essential to understand how food quality influences foraging decisions and constrains population persistence of wildlife for effective conservation management (Rothman 2015 (Snyder 1992, Diner et al 2009, Nie et al 2015 and omnivores (Kimball et al 1998) in different ecosystems. A major outcome of this study is an insight into how and why koalas use habitats and food tree species under different rainfall conditions in semi-arid regions.…”