Exploring the personalities of plants: Effects of intra-specific trait variation on individual fitness

Background/Question/Methods

Personality is described as the phenomenon that (animal-) individuals show systematic differences in their behavior, which are consistent over time and have consequences for the ecology and evolution of species and communities. Defining plant behavior as interactions between plant individuals and flower visitors or herbivores that are mediated by functional plant traits, we propose that plants have personalities as well, which may also be reflected in the reproductive success of plant individuals. In an experimental field study, we tested if the criteria of “personalities” are met by plants.

A dataset of flower interactions with arthropods during the entire lifespan of 97 plant individuals (germination to seed maturation) of Sinapis arvensis(Brassicacae) was used to define the personality of each plant individual. We ranked the daily interaction frequency between flower visitors and each plant individual and tested whether the ranking is consistent over the observation period. Additionally, we quantified different functional traits (morphology, secondary metabolites and phenology) allowing us to link personality, interactions, traits and reproductive success on an individual basis. We use the dataset to test the following hypotheses: a) plants have a personality; b) the personalities are shaped by trait characteristics; c) the plants’ personality determines its reproductive success.

Results/Conclusions

We found that the behavior of the plant individuals (total number of interactions between the plant individual and flower visitors) and the ranking of plants was consistent over time, which is in accordance with the concept of personalities. The personality patterns were correlated with flower traits such as display size of the flowers or the anther length as well as with reproductive success; indicating that plant personalities are characterized by functional traits with consequences for individual fitness.

Our findings suggest – for the first time – that plants have personalities analogous to animals, which are linking the intra-specific variation of functional plant traits and the reproductive success. We conclude that personalities may be the basis for the evolution in plant species with effects on the ecology of plant-animal communities.