Growth rate and life history shape plant resistance to herbivores

Abstract

Premise Plant defenses are shaped by many factors, including herbivory, lifespan, and mating system. Predictions about plant defense and resistance are often based on resource allocation trade‐offs with plant growth and reproduction. Additionally, two types of plant resistance, constitutive and induced resistance, are predicted to be evolutionary alternatives or redundant strategies. Given the variety of plant trait combinations and non‐mutually exclusive predictions, examining resistance strategies in related species with different combinations of growth and reproductive traits is important to tease apart roles of plant traits and evolutionary history on plant resistance. Methods Phylogenetic comparative methods were used to examine the potentially interacting influences of life history (annual/perennial), mating system (self‐compatible/self‐incompatible), and species growth rates on constitutive resistance and inducibility (additional resistance following damage) across Physalis species (Solanaceae). Results Resistance was evolutionarily labile, and there was no correlation between constitutive resistance and inducibility. Annual species with fast growth rates displayed higher constitutive resistance, but growth rate did not affect constitutive resistance in perennials. In contrast, inducibility was negatively associated with species growth rate regardless of life history or mating system. Conclusions The different effects of plant life history and growth rate on constitutive resistance and inducibility indicate that defensive evolution is unconstrained by a trade‐off between resistance types. The interactions among plant life history, growth, and herbivore resistance show that plant defense is shaped not only by herbivore environment, but also by plant traits that reflect a plant's evolutionary history and local selective pressures.

Building a barrier: investigating the defensive role of induced trichome production in herbicide exposed plants

“…Overall, these results suggest that in the presence of herbicide, genotypes with intermediate growth and high plasticity in trichome production, but not plasticity in the proportion of polymorphs, exhibit the highest fitness. These selection results align with past studies that indicate inducibility is negatively associated with species growth (Jacobsen 2022). Thus, while we did not find costs on induced trichomes in terms of fitness, the pattern of correlative selection in the presence of herbicide indicates a cost in terms of plant growth.…”

A bioenergetic framework for aboveground terrestrial food webs

“…A central tenant of the new perspective we propose (Figure 1) is the notion that plant species can be organized along a fast-slow growth axis [26][27][28], determining plant mass-specific metabolic rates and ultimately the flow of energy from primary production to higher trophic levels via consumption. Fast-growing plants invest in photosynthetic machinery at the expense of defenses and structural tissue [29], which itself is defensive because it is difficult to digest.…”

“…Because of these investments, fast growing plants tend to be leafier, more nutritious for consumers (lower C:N,P ratios and higher tissue digestibility), and less resistant but more tolerant to herbivory. This increased tolerance arises both because their ability to grow quickly allows them to quickly replace lost tissue and because their lack of investment in structure and defenses lowers the per unit cost of their tissue [29]. Slow-growing plants, in contrast, invest more heavily in structure and defenses that promote the longevity of their tissues and therefore tend to be larger, woodier, less nutritious for consumers, and more resistant but less tolerant of herbivory.…”