title: Changes in pollinator fauna affect altitudinal variation of floral size in a bumblebee-pollinated herb.
abstract: Geographic trait variations are often caused by locally different selection regimes. As a steep environmental cline along altitude strongly influences adaptive traits, mountain ecosystems are ideal for exploring adaptive differentiation over short distances. We investigated altitudinal floral size variation of Campanula punctata var. hondoensis in 12 populations in three mountain regions of central Japan to test whether the altitudinal floral size variation was correlated with the size of the local bumblebee pollinator and to assess whether floral size was selected for by pollinator size. We found apparent geographic variations in pollinator assemblages along altitude, which consequently produced a geographic change in pollinator size. Similarly, we found altitudinal changes in floral size, which proved to be correlated with the local pollinator size, but not with altitude itself. Furthermore, pollen removal from flower styles onto bees (plant's male fitness) was strongly influenced by the size match between flower style length and pollinator mouthpart length. These results strongly suggest that C. punctata floral size is under pollinator-mediated selection and that a geographic mosaic of locally adapted C. punctata exists at fine spatial scale.
authors.affiliation: Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Nagano
authors.affiliation: Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
authors.forename: Kota
authors.initials: K
authors.lastname: Abe
authors.affiliation: Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
authors.forename: Tomoaki
authors.initials: T
authors.lastname: Kitazawa
authors.affiliation: Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Hattori
authors.affiliation: Sugadaira Montane Research Center, University of Tsukuba Ueda, Nagano, 386-2201, Japan.
authors.forename: Akira S
authors.initials: AS
authors.lastname: Hirao
authors.affiliation: Department of Biology, Faculty of Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan ; Institute of Mountain Science, Shinshu University 3-1-1 Asahi, Matsumoto, Nagano, 390-8621, Japan.
authors.forename: Takao
authors.initials: T
authors.lastname: Itino
keywords: Geographic selection mosaic; local adaptation; mechanical fit; phenotypic selection; pollination efficiency