Pollen production per flower increases with floral display size across animal‐pollinated flowering plants

DA CUNHA, NICOLAY LEME; AIZEN, MARCELO ADRIÁN

AMERICAN JOURNAL OF BOTANY

BOTANICAL SOC AMER INC

Año: 2023

0002-9122

Premise: The number of open flowers on a plant (i.e., floral display size) can influenceplant fitness by increasing pollinator attraction. However, diminishing marginalfitness returns with increasing floral display are expected as pollinators tend to visitmore flowers per plant consecutively. An extended flower visitation sequenceincreases the fraction of ovules disabled by self‐pollination (ovule discounting) andreduces the fraction of a plant´s own pollen that is exported to sire seeds inother plants (pollen discounting). Hermaphroditic species with a genetic system thatprevents self‐fertilization (self‐incompatibility) would avoid ovule discounting and itsfitness cost, whereas species without such a genetically based barrier would not.Contrarily, pollen discounting would be an unavoidable consequence of a large floraldisplay irrespective of selfing barriers. Nevertheless, the increasing fitness costs ofovule and pollen discounting could be offset by respectively increasing ovule andpollen production per flower.Methods: We compiled data on floral display size and pollen and ovule productionper flower for 1241 animal‐pollinated, hermaphroditic angiosperm species, includingdata on the compatibility system for 779 species. We used phylogenetic general linearmixed models to assess the relations of pollen and ovule production to floraldisplay size.Results: Our findings provide evidence of increasing pollen production, but not ofovule production, with increasing display size irrespective of compatibility systemand even after accounting for potentially confounding effects like flower size andgrowth form.Conclusions: Our comparative study supports the pollen‐discount expectation of anadaptive link between per‐flower pollen production and floral display across animal-pollinatedangiosperms.