Heterospecific pollen effects vary with abiotic conditions

Studies that have evaluated the effects of heterospecific pollen (HP) receipt on plant reproductive success have generally overlooked the variability of the natural abiotic environment in which plants grow. Variability in abiotic conditions, such as light and water availability, has the potential to affect pollen–stigma interactions (i.e. conspecific pollen germination and performance), which will probably influence the effects of HP receipt. Thus, a more complete understanding of the extent, strength and consequences of plant–plant interactions via HP transfer requires better consideration of the range of abiotic conditions in which these interactions occur.

Celaya et al. evaluate the effects of two HP donors (Tamonea curassavica and Angelonia angustifolia) on the reproductive success of Cuphea gaumeri and find that HP receipt causes a decrease in pollen tube growth, but only when the availability of water, light or both is low, and not when the availability of both resources is high. The results show that the outcome of interspecific post-pollination interactions via HP transfer can be context-dependent and vary with abiotic conditions, thus suggesting that abiotic effects in natural populations may be under-estimated.