Plant-pollinator systems in heterostylous plant species : from genes to landscapes

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1) Flower visitation by Bombus diversus queens, stigmatic pollen load, and patterns of pollen carryover were measured under semi-natural experimental systems. It was revealed that spatial structure of Primula sieboldii population strongly affects pollination patterns by the bumblebee queens. Patterns of gene flow through both pollen and seeds were analyzed in natural and experimental populations of P. sieboldii in Hokkaido and central Honshu. According to the results, gene flow patterns depending on spatial structure of the population and interacted pollinator visitation were modeled.2) In natural populations of P. sieboldii in Hokkaido, seed set was limited in small or pollinator-limited populations due to pollen limitation. A hand-pollination experiment to simulate population fragmentation revealed that decrease in the possibility of multiple-donor pollination can lower progeny viability through germination failure and that selfed progeny produced by the long-styled self-compatible i … More ndividuals under pollinator limitation may not contribute successfully to the next generation due to strong inbreeding depression. It was revealed that the solitude of isolated plant population causes reproductive failure through pollination failure.3) Population spatial structure, flower visiting insects, seed set, and heterostylous characteristics of Primula jesoana, P. modesta, and P. kisoana, which are closely related with P. sieboldii were investigated in natural habitats. It was revealed that self- and intra-morph pollinations are incompatible and that effective pollinators are needed to set seeds in these species.4) Evaluation of pollination efficiency on the basis of data from a study for plant-pollinator systems on the scale of ecological community revealed the effectiveness of bumblebees as pollinators in a northern maritime grassland.5) A telemeter for bumblebees was not able to be developed because of the shortage of technical experts. However, we could find natural colonies of Bombus diversus. Analysis of the number of times of entrance and exit of the workers and pollen loads revealed the foraging profile and the development pattern of the colony.6) These results of the present study scaling from genes to landscapes can help designing plans for conservation and restoration of biological interactions between heterostylous plant species and their pollinators. Less