Phylogenetic and trait similarity to a native species predict herbivory on non-native oaks

Abstract

Introduced plants tend to experience less herbivory than natives, although herbivore loads vary widely. Herbivores may switch hosts onto an introduced plant for at least two reasons. They may recognize the novel plant as a potential host based on similarity of the plant's traits to the traits of one of its native hosts, a similarity that may or may not exhibit phylogenetic signal. Alternatively, herbivores may feed optimally, assessing which introduced plants provide the best nutrition irrespective of similarity to native species. Here, we created a phylogeny of 57 oak (Quercus) taxa, which were grown outside of their ranges in a common botanical garden that contained one abundant native oak (Quercus lobata). We used the phylogeny to estimate the phylogenetic conservatism of herbivory by two feeding guilds of insects (leaf chewers and leaf miners) and 11 plant traits expected to affect herbivore performance. We found high phylogenetic signal in chewing damage but not mining damage and all traits except for leaf maturation time. Introduced oaks that are more closely related to the native oak received more chewing and mining damage than distantly related oaks, and introduced oaks that had greater overall similarity in leaf traits also received higher chewing damage but not mining damage. These results demonstrate that interactions between introduced plants and their herbivores are driven independently by traits that track plant phylogeny and leaf traits that likely affect herbivore performance. community phylogeny ͉ enemy release ͉ introduced ͉ plant defense ͉ Quercus P lants that are introduced to regions outside of their natural ranges interact with the organisms that are already present in those regions, usually in the absence of an evolutionary history of interaction. Non-native plants may compete for resources, alter physical properties of their new ranges, and act as hosts for native herbivores (1). Understanding the interactions between an introduced plant and the local pool of herbivores has the potential to illuminate both the dynamics of economically significant non-natives, such as invasive species (2) and agricultural crops (3), and fundamental questions about the evolution of interactions between organisms that lack a history of coexistence (4). Indeed, although shared herbivores are not specifically invoked in the discussion that became known as Darwin's naturalization hypothesis (5), recent authors have suggested that herbivore sharing may complement competitive exclusion in geographically partitioning closely related species (6). Using non-native plants as a model, we tested long-standing evolutionary predictions about the relationships among phylogenetic affinities, plant traits, and host association by herbivores (7).Over the past 50 years, ecologists have used the hypothesis of ''enemy release'' to understand and manipulate interactions between introduced plants and herbivores (8). The enemy release hypothesis posits that fewer herbivores use a plant in its introduced range than in its native ra...

Global Patterns of Leaf Defenses in Oak Species

“…In the current study, we sample 56 oak taxa, representing each of the five major oak clades (Manos et al 1999;Pearse and Hipp 2009), including representatives from eastern North America, western North America, Mexico, Europe, and Asia. Species were selected based on their presence in a 40-year old stand of oaks at University of California, Davis Arboretum.…”

“…While this sample represents less than 15% of the entire genus, it represents a broad spectrum of the phylogenetic, geographic, and ecological diversity of the genus. Each taxon was represented by three individuals except in cases where fewer were present in the arboretum (Pearse and Hipp 2009). Nomenclature follows the Oaks Names Database (Trehane 2007).…”

Invasive Spiraea tomentosa: a new host for monophagous Earias clorana?

“…The rate at which neophytes are colonised by local herbivorous fauna depends on the degree of phylogenetic similarity of new host plants and their native counterparts, as well as the quality of food, which affects the development of these herbivores (Agrawal and Kotanen 2003;Pearse and Hipp 2009). For example, invasive Prunus serotina Ehrh.…”

Third-party mutualists have contrasting effects on host invasion under the enemy-release and biotic-resistance hypotheses

“…This is biologically similar to environments where the plant may be invading a novel habitat that already contain plants that are phylogenetically similar and thus contain herbivores with trait values that match the invading plant. Many studies have found correlations between phylogenetic distance and antagonistic pressures on plants (Pearse and Hipp 2009;Ness et al 2011;Parker et al 2015). The phylogenetic composition of a community may have as great an effect on the outcome of invading plants as the ecological composition.…”