Relative stable interannual variation in plant–plant pollen transfer rather than the plant–pollinator network of a subalpine meadow

Abstract

Previous studies have shown that plant–pollinator mutualistic interactions experience highly interannual variation. Given that pollinators often move across multiple plant species, the plant‒plant interactions that take place via heterospecific pollen (HP) transfer may also vary temporally, which could have important implications for floral evolution and community assembly. Here, we evaluated the interannual variation in plant–pollinator networks and plant‒plant heterospecific pollen transfer (HPT) networks of a subalpine meadow community in Southwest China for three consecutive years. The interactions largely varied between years for both network types. The composition of donor-species HP deposited on the plants varied less than did the visit composition of the pollinators, which suggested that HP could be transferred from identical donor species to recipient species through different shared pollinators between years. The plant species were at more similar positions in the HPT network than they were in the plant–pollinator network across years. Moreover, the more generalized plant species in the plant–pollinator network tended to export their pollen grains and more strongly influence HPT. We evaluated the relatively stable structure of the HPT network compared with the plant–pollinator network, which represents an important step in the integration of plant–pollinator and plant‒plant interactions.

Heterospecific pollen avoidance strategy prevails in the generalized plant–pollinator network on Yongxing Island

“…Although HP avoidance and HP tolerance are both evolutionary stable strategies for species coexistence (Fang et al., 2019 ), most species evolved the HP avoidance mechanism for reducing HP deposition on stigmas, especially in a generalized pollination system, which have high pollinator sharing. Generalized plants are more likely to receive HP transferred by generalized pollinators from many other co‐flowering plant species (Arceo‐Gómez, Abdala‐Roberts, et al., 2016 ; Fang et al., 2023 ; Lopes et al., 2022 ). However, although HP deposition on stigmas is mainly carried out by pollinators' moves among co‐flowering plant species, the number of HP grains on stigmas is independent of the number of pollinators' moves.…”

“…Generalized plants are more likely to receive HP transferred by generalized pollinators from many other co-flowering plant species (Arceo-Gómez, Abdala-Roberts, et al, 2016;Fang et al, 2023;Lopes et al, 2022). However, although HP deposition on stigmas is mainly carried out by pollinators' moves among co-flowering plant species, the number of HP grains on stigmas is independent of the number Note: The number of stigmas used per species is indicated in parentheses after the species name.…”

“…This overlap may increase the possibility of heterospecific pollen (HP) transfer and deposition on stigmas (Fang & Huang, 2016 ; Flanagan et al., 2009 ; Huang et al., 2015 ; Traveset et al., 2013 ). HP deposition on stigmas has negative impacts on plant reproduction through clogging stigmas or pollen interference, which further affects the structure of plant communities (Arceo‐Gómez, 2021 ; Arceo‐Gómez, Kaczorowski, et al., 2019 ; Ashman & Arceo‐Gómez, 2013 ; Briggs et al., 2015 ; Fang et al., 2023 ; Muchhala & Thomson, 2012 ). On oceanic islands, plant and pollinator species tend to be generalized, and some can even be super‐generalists; this means that plants are visited by many pollinator species, and pollinators, in turn, visit a number of plant species (Traveset et al., 2013 ; Traveset et al., 2016 ; Wang et al., 2021 ; Wang, Fu, Shi, Zhao, et al., 2023 ; Wang, Wen, Qian, et al., 2020 ; Wang, Zeng, et al., 2020 ).…”