Sensitive plant (Mimosa pudica) hiding time depends on individual and state

Abstract

The decisions animals make to adjust their antipredator behavior to rapidly changing conditions have been well studied. Inducible defenses in plants are an antipredator behavior that acts on a longer time scale, but sensitive plants, Mimosa pudica, have a much more rapid antipredator response; they temporarily close their leaves when touched. The time they remain closed is defined as hiding time. We studied hiding time in sensitive plants and found that individual plants differed significantly in their hiding times. We then showed that the effect of individual explained substantial variation in hiding time on a short time scale. Finally, on a longer time scale, individuality persisted but the amount of variation attributed to individual decreased. We hypothesized that variation in plant condition might explain this change. We therefore manipulated sunlight availability and quantified hiding time. When deprived of light for 6 h, sensitive plants significantly shortened their hiding times. But when only half a plant was deprived of light, hiding times on the deprived half and light exposed half were not significantly different. This suggests that overall condition best explains variation in sensitive plant antipredator behavior. Just like in animals, sensitive plant antipredator behavior is condition dependent, and, just like in animals, a substantial amount of the remaining variation is explained by individual differences between plants. Thus, models designed to predict plasticity in animal behavior may be successfully applied to understand behavior in other organisms, including plants.

Keywords: Hiding time; Optimal escape behavior; Personality; Sensitive plants.

Figure 1. Hiding time (s) as a function of the individual plant.

The plotted values are the median hiding times, quartiles, fences (1.5 times the interquartile range), and outliers.

Figure 2. Hiding time (s) as a function of trial number, grouped by individual.

(A) Data points and regression lines for individuals stimulated immediately upon reopening (experiment 2a). (B) Data points and regression lines for individuals stimulated every 48 h (experiment 2b). Thick line (red in on-line version) illustrates the mean hiding time across trials.

Figure 3. Difference in hiding time (s) as a function of total plant treatment (black plastic bag, clear plastic bag, no bag).

Plotted values are the initial and final hiding times connected by a sloped line.