Altruism or Selfishness: Floral behavior based on genetic relatedness with neighboring plants

Kin recognition in plants may lead to plastic changes in their behavior, such as altering their floral display size. In this study, we conducted evolutionary simulations of the two floral tactics utilized by plants depending on the genetic relatedness of their neighboring plants. We found that the evolutionary consequences of the floral display size in plants can be classified into four types, based on whether the floral display size increased or decreased in comparison with the case plants disable of kin recognition. As a typical result, the plants that grew with kin behaved altruistically by increasing their floral display size, whereas those that coexisted with strangers behaved selfishly by reducing their floral display size, as is observed in the field. The kin recognition and resultant evolution of the floral display size had the spillover effect on the population scale. Kin recognition generally increased the intraspecific variation in the floral display size and seed production, and decreased the genetic diversity of plant populations.