Floral visitors and reproductive success in two sequentially flowering Lindera shrubs (Lauraceae) of central Japan

Two Lindera species (Lindera praecox and Lindera triloba) are distributed sympatrically along the Pacific Ocean side of the main island of Japan. They are similar, but not identical, in habitat preference and flowering season. Slight differences in these traits have been proposed, but a comparative study on the reproductive ecology of these two species has not yet been conducted. To reveal the interspecies differences between these two Lindera spp. and characterize the life historical characteristics related to their reproduction, we assessed differences in floral visitors and reproductive ecology (fruit set, seed and pulp weights, and pollen limitation) between species and sexes over a period of 3 years. A total of 39 species (458 individuals) of floral visitors, approximately 70% of which comprised three Coleoptera species, were collected from plants of both species and sexes. The number of insect species that visited the late-flowering species, L. triloba, was significantly higher than the number that visited the early-flowering species, L. praecox. However, the numbers of visitors were not significantly different between species. The fruit set was higher in L. triloba than in L. praecox, but L. praecox pulps were heavier than those of L. triloba. Our study revealed interspecies differences in floral visitors and reproductive success between two species and indicate the possible differences of reproductive strategy of these two Lindera spp.