Kin discrimination allows plants to modify investment towards pollinator attraction

Abstract

Pollinators tend to be preferentially attracted to large floral displays that may comprise more than one plant in a patch. Attracting pollinators thus not only benefits individuals investing in advertising, but also other plants in a patch through a 'magnet' effect. Accordingly, there could be an indirect fitness advantage to greater investment in costly floral displays by plants in kin-structured groups than when in groups of unrelated individuals. Here, we seek evidence for this strategy by manipulating relatedness in groups of the plant Moricandia moricandioides, an insect-pollinated herb that typically grows in patches. As predicted, individuals growing with kin, particularly at high density, produced larger floral displays than those growing with non-kin. Investment in attracting pollinators was thus moulded by the presence and relatedness of neighbours, exemplifying the importance of kin recognition in the evolution of plant reproductive strategies.

Fig. 1

Effect of intraspecific social environment on floral display. Least-square means (± s.e.m.) of a advertising effort, b number of flowers, and c mean petal mass of focal plants. Focal plants were grown alone, with three neighbours, or with six neighbours, which were either kin (orange symbols) or non-kin (blue symbols). Solitary plants were grown in large (red diamonds), medium-sized (grey circles) and small pots (grey squares). Different letters indicate significant differences between solitary plants (GLMM test: P < 0.05, Supplementary Table 3), whereas differences between kin and non-kin treatments, and between levels of group size, are indicated above the symbols (GLMM test: ns, P > 0.05; *, P < 0.05, Table 1). P-values of comparisons between solitary plants vs. focal plants within groups are shown in Supplementary Table 2. All P-values were corrected for multiple comparisons using Holm’s adjustment

Fig. 2

Effect of intraspecific social environment on plant size. Least-square means (± s.e.m.) of a plant above-ground biomass, and b plant height. Focal plants were grown alone, with three neighbours, or with six neighbours, which were either kin (orange symbols) or non-kin (blue symbols). Solitary plants were grown in large (red diamonds), medium-sized (grey circles) and small pots (grey squares). Different letters indicate significant differences between solitary plants (GLMM test: P < 0.05, Supplementary Table 3), whereas differences between kin and non-kin treatments, and between levels of group size, are indicated above the symbols (GLMM test: ns, P > 0.05; *, P < 0.05, Table 1). P-values of comparisons between solitary plants vs. focal plants within groups are shown in Supplementary Table 2. All P-values were corrected for multiple comparisons using Holm’s adjustment