Resource availability affects kin selection in two cultivars of Pisum sativum

Recent works have demonstrated that plants follow complex decision rules when competing with conspecific neighbours (kin or strangers) and foraging resources. According to kin selection theory, cooperative behaviours toward relatives (i.e. reduced competition) can increase actor’s extended fitness, with advantages to the whole group of relatives. Similarly, several species have reported to adopt different foraging strategies by non-additively integrating information about the presence of neighbours and resource availability in the soil. Here we investigated whether (a) Pisum sativum responds to kin recognition, and (b) kin selection is context dependent. By using two commercial dwarf cultivars in all possible combinations and two levels of nutrients we followed plant growth evaluating their complex behavioural traits. Plants growing with strangers showed increased vegetative biomass production and allocation after 30 days of growth, suggesting an increase of competitive effect. Furthermore, kin selection was stronger in low-resources. Interestingly, at the end of the growth cycle, stranger pairs showed a reduced biomass and fruit production in low resource conditions but not in high nutrition. These results suggest that P. sativum responds selectively to neighbour identity by cooperating with kin neighbours; and they provide evidence that the magnitude of the cooperative response toward kin plants increases as environmental conditions become more stressful.