How environmental factors affect pollen performance: Ecological and evolutionary perspectives

We review the effects of herbivory and other environmental factors on pollen performance in plants. We conclude that natural levels of variation in herbivory and other environmental factors during pollen development are often sufficient to cause significant differences in pollen performance, and that the differences in pollen performance are likely to be caused by differences in the provisioning of pollen grains. From an evolutionary perspective, we discuss how pollen and ovule provisioning may be negatively genetically correlated and how this would maintain genetic variation for pollen performance within populations. Furthermore, the highly plastic nature of pollen performance provides the potential for genotypes to respond differently to environmental variation (genotype-environment interactions), which would also promote the maintenance of genetic variation in pollen performance.