Effect of heterospecific pollen deposition on pollen tube growth depends on the phylogenetic relatedness between donor and recipient

Nathália Susin Streher; Pedro Joaquim Bergamo; Tia-Lynn Ashman; Marina Wolowski; Marlies Sazima

doi:10.1093/aobpla/plaa016

Effect of heterospecific pollen deposition on pollen tube growth depends on the phylogenetic relatedness between donor and recipient

AoB Plants. 2020 Jun 5;12(4):plaa016. doi: 10.1093/aobpla/plaa016. eCollection 2020 Aug.

Authors

Nathália Susin Streher^{1

2}, Pedro Joaquim Bergamo³, Tia-Lynn Ashman², Marina Wolowski⁴, Marlies Sazima⁵

Affiliations

¹ Graduate Program in Plant Biology, University of Campinas, Campinas, SP, Brazil.
² Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
³ Graduate Program in Ecology, University of Campinas, Campinas, SP, Brazil.
⁴ Institute of Natural Sciences, Federal University of Alfenas, Alfenas, MG, Brazil.
⁵ Plant Biology Department, Institute of Biology, University of Campinas, Campinas, SP, Brazil.

Abstract

Co-flowering plant species may interact via pollinators leading to heterospecific pollen transfer with consequences for plant reproduction. What determines the severity of heterospecific pollen effect on conspecific pollen performance is unclear, but it may depend on the phylogenetic relatedness of the interactors (pollen donors and recipient). The heterospecific pollen effect might also depend on the extent to which plants are exposed to heterospecific pollen over ecological or evolutionary timescales. For instance, generalist-pollinated plant species might tolerate heterospecific pollen more than specialists. Here, we tested whether heterospecific pollen effects are stronger between closely related species than phylogenetically distant ones in a tropical highland community. Then, based on these results, we determined whether responses to heterospecific pollen were stronger in generalized vs. specialized plant species. We applied heterospecific pollen from close (congeneric) or distant (different families) donors alone or with conspecific pollen on stigmas of three recipient species (one generalist, Sisyrinchium wettsteinii; and two specialists, Fuchsia campos-portoi and Fuchsia regia) and scored pollen tube performance in styles. In all species, pollen from closely related donors grew pollen tubes to the base of the style indicating a high potential to interfere with seed set. Conversely, distantly related heterospecific pollen had no effect on either specialist Fuchsia species, whereas enhanced performance of conspecific pollen was observed in generalist S. wettsteinii. The strong effect of phylogenetic relatedness of donor and recipient might have obscured the role of pollination specialization, at least for the three species examined here. Therefore, phylogenetic relatedness mediated the effect of heterospecific pollen on post-pollination success, with possible consequences for reproductive trait evolution and community assembly for further studies to explore.

Keywords: Competition; facilitation; interspecific pollen transfer; pollen germination; pollinator sharing.