Reproductive interference between a periodical mass-flowering plant and an annual-flowering plant of Strobilanthes

ID: 613 / 253

Category: Abstract

Track: Pending

Proposed Symposium Title: Reproductive interference between a periodical mass-flowering plant and an annual-flowering plant of Strobilanthes

Authors:

Sachiko Nishida1, Akiyo Naiki2, Satoshi Kakishima3

Affiliations: 1 Nagoya University, Nagoya, Japan 2 University of the Ryukyu, Yaeyama, Japan 3 Showa University, Fujiyoshida, Japan

Abstract:

Reproductive interference, an interspecific interaction associated with mating systems that adversely affects the fitness of the recipient species, has an aspect of positive frequency dependence and exerts stronger effects when the recipient is in the minority. To clarify how this aspect is involved in a mass-flowering phenomenon, we studied the interaction between two species of Strobilanthes.

Strobilanthes flexicaulis is a monocarpic perennial plant with mass-flowering on Okinawa Island, Japan, whereas in other regions it is polycarpic or monocarpic with no mass-flowering. A closely related species, S. tashiroi, is a polycarpic perennial with annual-flowering and co-occurs with S. flexicaulis only on Okinawa Island. We hypothesized that mass-flowering would increase the frequency of S. flexicaulis flowers and reduce the negative effects of reproductive interference from S. tashiroi. To test this hypothesis, we carried out artificial pollination between the two species and examined the negative effect of counterpart species pollen on the seed set of the focal species.

The results showed that the negative effect of counterpart species pollen was sometimes recognized in S. flexicaulis, depending on the population and year, whereas it was always recognized in S. tashiroi. These results suggest that reproductive interference is bidirectional, but stronger from S. flexicaulis to S. tashiroi than vice versa. It is likely that reproductive interference from S. tashiroi is only partly responsible for the mass-flowering of S. flexicaulis, whereas reproductive interference from S. flexicaulis was enhanced by the mass-flowering phenomenon and reduced S. tashiroi offspring in the regions where the two species were co-occuring.

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Key words: mass-flowering, reproductive interference, Strobilanthes flexicaulis, Strobilanthes tashiroi