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Flowering plants do not occur alone and often grow in mixed-species communities where pollinator sharing is high and interactions via pollinators can occur at pre- and post-pollination stages. While the causes and consequences of pre-pollination interactions have been well studied little is known about post-pollination interactions via heterospecific pollen (HP) receipt, and even less about the evolutionary implications of these interactions. In particular, the degree to which plants can evolve tolerance mechanisms to the negative effects of HP receipt has received little attention. Here, we aim to fill this gap in our understanding of post-pollination interactions by experimentally testing whether two co-flowering Clarkia species can evolve HP tolerance, and whether tolerance to specific HP ‘genotypes’ (fine-scale local adaptation to HP) occurs. We find that Clarkia species vary in their tolerance to HP effects. Furthermore, conspecific pollen performance and the magnitude of HP effects were related to the recipient's history of exposure to HP in C. xantiana but not in C. speciosa. Specifically, better conspecific pollen performance and smaller HP effects were observed in populations of C. xantiana plants with previous exposure to HP compared to populations without such exposure. These results suggest that plants may have the potential to evolve tolerance mechanisms to HP effects but that these may occur not from the female (stigma, style) but from the male (pollen) perspective, a possibility that is often overlooked. We find no evidence for fine-scale local adaptation to HP receipt. Studies that evaluate the adaptive potential of plants to the negative effects of HP receipt are an important first step in understanding the evolutionary consequences of plant–plant post-pollination interactions. Such knowledge is in turn crucial for deciphering the role of plant–pollinator interactions in driving floral evolution and the composition of co-flowering communities.
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Direct tracking of pollen with quantum dots reveals surprising uniformity in dispersal distance across 11 populations of an annual plant
Abstract Premise Pollen movement is a crucial component of dispersal in seed plants. Although pollen dispersal is well studied, methodological constraints have made it challenging to directly track pollen flow within multiple populations across landscapes. We labeled pollen with quantum dots, a new technique that overcomes past limitations, to evaluate the spatial scale of pollen dispersal and its relationship with conspecific density within 11 populations of Clarkia xantiana subsp. xantiana , a bee‐pollinated annual plant. Methods We used experimental arrays in two years to track pollen movement across distances of 5–35 m within nine populations and across distances of 10–70 m within two additional populations. We tested for distance decay of pollen dispersal, whether conspecific density modulated dispersal distance, and whether dispersal kernels varied among populations across an environmentally complex landscape. Results Labeled pollen receipt did not decline with distance over 35 m within eight of nine populations or over 70 m within either of two populations. Pollen receipt increased with conspecific density. Overall, dispersal kernels were consistent across populations. Conclusions The surprising uniformity in dispersal distance within different populations was likely influenced by low precipitation and plant density in our study years. This suggests that spatiotemporal variation in the abiotic environment substantially influences the extent of gene flow within and among populations.
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- PAR ID:
- 10441315
- Date Published:
- Journal Name:
- American Journal of Botany
- Volume:
- 110
- Issue:
- 7
- ISSN:
- 0002-9122
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1002/ajb2.16201
