A comparison of plants and animals in their responses to risk of consumption

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Anti-herbivore defense shows high levels of both inter- and intraspecific variability. Defending against herbivores may be costly to the plant when it requires a tradeoff in allocation between defense and other missed opportunities, such as reproduction. Indeed, the plastic expression of defensive traits allows the plant to invest resources in defense only when the risk of being damaged actually increases, avoiding wasted resources. Plants may assess risk by responding to volatile cues emitted by neighbors that are under attack. Most plastic responses likely depend on environmental conditions. In this experiment, we investigated the effect of water availability on resistance induced by volatile cues in sagebrush. We found that plants receiving additional water over summer and/or volatile cues from neighbor donor plants showed reduced herbivore damage compared to control plants. Interestingly, we found no evidence of interactions between additional water and volatile cues. We performed an inferential analysis comparing historical records of the levels of herbivore damage during different years that had different temperature and precipitation accumulations. Results confirmed findings from the experiment, as the regression model indicated that sagebrush was better defended during wetter and hotter seasons. Reports from the literature indicated that sagebrush is extremely sensitive to water availability in the soil. We suggest that water availability may directly affect resistance of herbivory as well as sensitivity to cues of damage. Costs and benefits of allocating resources to defensive traits may vary with environmental conditions.

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Precipitation affects plant communication and defense

Pezzola

Mancuso

Karban

2017

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“…, Karban et al. ). Plants are rooted in place, making flight impossible so they respond to risk by reallocating resources, developing tolerance to partial tissue loss, and inducing defenses.…”

Section: Benefits Of Incorporating Plants Into the Judgment/decision‐mentioning

confidence: 99%

“…, Karban et al. ). Plants are more tolerant of loss of some tissue than are most animals, in part because plants are composed of redundant and semi‐autonomous tissues and receptors.…”

Section: Benefits Of Incorporating Plants Into the Judgment/decision‐mentioning

confidence: 99%

A judgment and decision‐making model for plant behavior

Karban

Orrock

2018

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Recently plant biologists have documented that plants, like animals, engage in many activities that can be considered as behaviors, although plant biologists currently lack a conceptual framework to understand these processes. Borrowing the well-established framework developed by psychologists, we propose that plant behaviors can be constructively modeled by identifying four distinct components: (1) a cue or stimulus that provides information, (2) a judgment whereby the plant perceives and processes this informative cue, (3) a decision whereby the plant chooses among several options based on their relative costs and benefits, and (4) action. Judgment for plants can be determined empirically by monitoring signaling associated with electrical, calcium, or hormonal fluxes. Decision-making can be evaluated empirically by monitoring gene expression or differential allocation of resources. We provide examples of the utility of this judgment and decision-making framework by considering cases in which plants either successfully or unsuccessfully induced resistance against attacking herbivores. Separating judgment from decision-making suggests new analytical paradigms (i.e., Bayesian methods for judgment and economic utility models for decision-making). Following this framework, we propose an experimental approach to plant behavior that explicitly manipulates the stimuli provided to plants, uses plants that vary in sensory abilities, and examines how environmental context affects plant responses. The concepts and approaches that follow from the judgment and decision-making framework can shape how we study and understand plant-herbivore interactions, biological invasions, plant responses to climate change, and the susceptibility of plants to evolutionary traps.

Population‐wide shifts in herbivore resistance strategies over succession

Kalske

Kessler

2020

As a strategic cost‐saving alternative to constitutive resistance, induction of resistance against herbivores in plants can be especially beneficial when enemies are scarce or variable in abundance. Although probably describing the two ends of a continuum, constitutive and induced resistance strategies have long been observed to trade off within species. Examining these traits among populations along a successional gradient can help explain how temporally variable environments can maintain genetic variation and how ecosystem processes are affected by shifting plant resistance trait expression over time. Here we leverage large experimental plots that represent a chronosequence of succession up to 15 yr in combination with common garden experiments to examine changes in the selective environment and genetic differences in tall goldenrod’s (Solidago altissima) constitutive and induced resistance. We show that resistance against a specialist herbivore Trirhabda virgata was inducible in the plants originating from midsuccession, which coincides with the largest loads of herbivores. The flavonoid compound content of the leaves varied with successional stage of the population of origin, which is indicative of constitutive differences in secondary metabolite production. Finally, there was a clear trade‐off between constitutive and induced resistance. Our study indicates that selection for resistance traits within a population can be highly variable over time and likely result in genetically determined shifts of resistance strategies over relatively short time periods via genotype sorting.