How do specialist and generalist seed predators affect the highly variable and synchronized seed dispersal of Photinia glabra (Rosaceae), a fleshy-fruited tree?

• Published in: Plant ecology 2023-02, Vol.224 (2), p.189-201
• Main Authors: Hirayama, Kimiko, Masuda, Asuka, Kurokawa, Satoshi, Terada, Ayaka, Sasaki, Mizuki, Kuge, Ayami
• Format: Article
• Language: English
• Subjects: Annual variations; Applied Ecology; Biodiversity; Biomedical and Life Sciences; Community & Population Ecology; Crop production; Damage; Dispersion; Ecology; Flowering; Flowers; Fruit; Fruits; Insects; Life Sciences; Photinia glabra; Plant Ecology; Predators; Reproductive organs; Sea level; Seed dispersal; Seed industry; Seeds; Terrestial Ecology; Trees
• ISSN: 1385-0237; 1573-5052
• DOI: 10.1007/s11258-023-01289-2

Fleshy fruits are used by various animals, including legitimate seed dispersers and fruit and seed predators. To clarify the overall effect of these plant-animal interactions on the annual fruit production and seed dispersal pattern of fleshy-fruited species, we investigated the demographic processes from flowering to fruit removal and their effect on seed dispersal of Photinia glabra , which shows variable seed dispersal and has a specialized insect seed predator, Argyresthia assimilis , tightly dependent on its fruit. We sorted all reproductive organs for ten trees from 2013 to 2021 on Takaragaike Hill in northern Kyoto City, western Japan (35° 3′N, 135° 46′E; 110–150 m above mean sea level). The amplitude of intra-individual variability ( CV i ¯ value of 0.97) and inter-individual synchrony ( r p ¯ value of 0.30) in flower production was relatively weak, which would not fully contribute to the reduction in fruits damaged by A. assimilis . Compared with flower production, we observed highly variable ( CV i ¯ value of 1.39) and synchronous ( r p ¯ value of 0.89) seed dispersal by legitimate seed dispersers within individuals. Reproductive loss due to generalist avian seed predators was the most prominent factor contributing to annual variability in total pre-dispersal losses, followed by losses due to A. assimilis . Annual variability in the visitation frequency of avian seed predators, especially migratory Fringilla montifringilla , may affect the amount of ripened fruit available to legitimate seed dispersers. We suggest that the effect of damage due to generalist seed predators directly determines the intermittent and highly synchronous seed dispersal of P. glabra .