Spatial variation in female fertility related to interactions with flower consumers and pathogens in a forest metapopulation of Primula sieboldii

Abstract

Antagonistic biological interactions with flower consumers and pathogens may influence reproductive success of flowering plants, affecting population dynamics and natural selection for floral traits. However, ecological and evolutionary consequences of the interactions may depend on both spatial and temporal patterns of the interactions. In a forest metapopulation of Primula sieboldii E. Morren, an endangered clonal plant species, we measured between-subpopulation patterns of seed sets and interactions with an influential flower consumer, a rove beetle, Eusphalerum bosatsu Watanabe, and a specific smut fungal pathogen, Urocystis tranzschelina (Lavrov) Zundel (Ustilaginales), for three years. Mean female fertility (seed set per flower) for individual subpopulations fluctuated moderately among years but was highly variable within each year among the five subpopulations studied. In two subpopulations, the impact of Eusphalerum beetle, was sufficiently large to result in almost complete failure in seed production over eight years including the three study and five previous preliminary observation years. In the two other subpopulations, seed set failure was caused by infection by the smut fungus. Infected capsules which constitute 10-30~ of the capsules produced in the subpopulations were filled with ustilospores instead of seeds. In the subpopulation that escaped flower damage by Eusphalerum beetles and smut fungal infection, seed sets of both pin and thrum flowers were much higher than in the other subpopulations. The spatial restriction of individual antagonistic agents to a part of subpopulations suggest that dispersal of the agents, as well as the mode of spatial subdivision of the plant population would be important for determining the overall effects of antagonistic interactions on plant performances at the metapopulation level.

Florivory affects pollinator visitation and female fitness in Nemophila menziesii

“…Our knowledge of how plants respond to herbivory comes primarily from experiments focusing on damage to nonreproductive tissue, even though petal damage can be quite severe with large consequences for plant Wtness in some populations (Washitani et al 1996;Wolfe 2002;Riba-Hernandez and Stoner 2005). In this study, I showed that both natural and artiWcial damage to reproductive tissues resulted in a variety of negative Wtness eVects in N. menziesii, but with little evidence of indirect eVects of damage.…”

Testing the ‘assortative mating’ hypothesis on a variation maintenance mechanism for flowering time within a forest‐floor population of Primula sieboldii

“…The reproductive success of Primula sieboldii largely depends on the availability of pollen mediated by queen bumblebees (Washitani et al . 1994b), and is influenced by antagonistic biological interactions, for example, with a flower consumer rove beetle and/or a specific smut fungal pathogen (Washitani et al . 1996).…”

Effects of population spatial structure on the quantity and quality of seeds set byPrimula sieboldii(Primulaceae)

“…Bumblebees leave clear claw marks on flower petals, which can be used as an index of pollinator availability. As for antagonistic biotic agents, a flower consumer, a rove beetle, Eusphaleum usphaleum bosatsu Watanabe, and a specific smut fungal pathogen, Urocrystis tranzschelina (Lavrov) Zundel (Ustilaginales) have been shown to lower the female fertility of P. sieboldii (Washitani et al . 1996).…”