Floral display size does not affect the distribution of paternal diversity in Silene dioica
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Premise of the study
Paternal diversity and its distribution within maternal plants is governed by various factors, including frequency of pollinator visits, patterns of pollinator movement and pollen carryover. Floral display size may have opposite effects on fruit and plant-level paternal diversity, because plants with large displays should receive more pollinator visits but also more sequential probes per visit.
Methods
To investigate the effect of floral display size on the distribution of paternal diversity in Silene dioica , we genotyped and assigned paternity for 1320 seeds sampled in several fruits per plant in control and manipulated females, whose flower number was artificially increased. We estimated within-fruit paternal diversity and sire profile dissimilarity among fruits and compared these metrics between control and manipulated plants. We then studied pollen carryover using controlled pollinator visits and pollen counts.
Key results
Most fruits were multiply sired, but we found no effect of flower supplementation on within-fruit paternal diversity. Sire profiles were more similar between fruits located on the same than on different females, but sire profile similarity was not higher within manipulated than within control plants. The pollen deposition curve was steep, with an increasing carryover fraction throughout the visitation sequence.
Conclusions
Our results suggest that the effect of floral display size on pollinator foraging behaviour is too weak to affect paternal diversity and its distribution in S. dioica , or that other processes, such as limited pollen carryover and spatially restricted pollen dispersal, blur the effect of pollinator visit frequency and movements on sire profiles.
