Kin recognition in an annual plant

Abstract

Kin recognition is important in animal social systems. However, though plants often compete with kin, there has been as yet no direct evidence that plants recognize kin in competitive interactions. Here we show in the annual plant Cakile edentula, allocation to roots increased when groups of strangers shared a common pot, but not when groups of siblings shared a pot. Our results demonstrate that plants can discriminate kin in competitive interactions and indicate that the root interactions may provide the cue for kin recognition. Because greater root allocation is argued to increase below-ground competitive ability, the results are consistent with kin selection.

Figure 1

(a) Root allocation and (b) total mass for groups of four C. edentula plants grown either in single pots (solitary) or in one larger shared pot (root neighbours). The groups were either siblings (kin) or from four different maternal families (strangers). Root allocation is the least square mean from an ANCOVA with fine root mass as the dependent variable and leaf mass as the covariate (n=96). Bars indicate 1 s.e.

Figure 2

Scatter plot of reproductive mass versus aboveground vegetative mass for single plants of C. edentula. Lines indicate second-order regressions of reproductive mass on vegetative mass for each root treatment. No significant kin or kin×root effects were found. n=332.