Pollen Limitation in the Alpine: A Meta-Analysis

Abstract

Pollen limitation (PL) is thought to be an important factor driving the evolution of floral traits in alpine plants. However, results of pollen supplementation experiments in alpine plants do not always show high levels of PL, and a general review of the importance of PL on alpine-plant reproduction is needed. We assessed to what extent alpine plants are pollen limited, and whether the intensity of PL differs between alpine and lowland species. Moreover, we assessed whether or not PL of alpine species depends on their reproductive system and, finally, whether the outcome of PL studies depends on whether supplemental-pollination was done at the whole-plant level or within a subset of available flowers. We performed both classical and phylogenetic meta-analysis. Our results show that alpine plants are pollen limited. However, PL did not differ significantly between alpine and lowland species. In the alpine, self-incompatible and self-compatible species show similar levels of PL. We did not find differences in PL between different manipulation levels. These results will help understand the real importance of PL of seed production in the alpine. We identify gaps in our knowledge of PL in the alpine that could serve to guide future directions of research in this field.