Leaf-folding response of a sensitive plant shows context-dependent behavioral plasticity
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The fast touch-induced folding of leaves in sensitive plants may function for deterring herbivores, but it relies on energetically costly action potentials and interferes with photosynthesis. Here, we tested whether the intensity of the folding response in Mimosa pudica was modulated based on previous experiences, and whether the modulation was dependent on the probability of exposure to herbivores or pollinators. Younger leaves (under higher herbivory risk) reopened faster with repetitions but showed complete folding at all trials, which should be more effective as defense, but limits light exposure for longer; older leaves changed from complete to partial folding with trials, but maintained similar reopening times, which should decrease loses in photosynthesis but is less effective as defense. Unlike leaves away from inflorescences, leaves near inflorescences (i.e. more likely to be touched by flower visitors, a non-damaging stimulus) marginally decreased reopening times and shifted from complete to partial folding, a combination that decreases to the least the time leaves are light limited. All leaves showed an increased response when a new stimulus was presented after the repeated trials, suggesting that the decrease in response after repeated stimulation was not caused by mechanism exhaustion. This study shows habituation-like plasticity in a plant thigmonastic response that conforms to expectations of behavioral ecology theory usually applied to animals.
KeywordsSeismonastic Thigmonastic Mimosa pudica Touch-induced movements Behavioral plasticity Habituation
We thank the coordinators of the ETC 02-13 “viajesan” field course, Alejandro Farji-Brener and Federico Chinchilla, for making this project possible. We thank Katherine Amador and Audrey Amador for assistance locating field sites; Catalina Salazar and Esteban Ramírez for valuable help in the field; Conservation Land Trust and Carlos Figuerero for let us work at their field stations; Ulrich Mueller, Brian Barret, Emma Dietrich, Melissa Kardish, Chi-Chun Fang, Rong Ma, Quinn McFrederick, and an anonymous reviewer for comments to earlier versions of this manuscript. The Organization for Tropical Studies provided logistical and financial support.
Conflict of interest
The authors declare that they have no conflict of interest.
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