title: Geographic variation in seed traits within and among forty-two species of Rhododendron (Ericaceae) on the Tibetan plateau: relationships with altitude, habitat, plant height, and phylogeny.
abstract: Seed mass and morphology are plant life history traits that influence seed dispersal ability, seeding establishment success, and population distribution pattern. Southeastern Tibet is a diversity center for Rhododendron species, which are distributed from a few hundred meters to 5500 m above sea level. We examined intra- and interspecific variation in seed mass and morphology in relation to altitude, habitat, plant height, and phylogeny. Seed mass decreased significantly with the increasing altitude and increased significantly with increasing plant height among populations of the same species. Seed mass differed significantly among species and subsections, but not among sections and subgenera. Seed length, width, surface area, and wing length were significantly negative correlated with altitude and significantly positive correlated with plant height. Further, these traits differed significantly among habitats and varied among species and subsection, but not among sections and subgenera. Species at low elevation had larger seeds with larger wings, and seeds became smaller and the wings of seeds tended to be smaller with the increasing altitude. Morphology of the seed varied from flat round to long cylindrical with increasing altitude. We suggest that seed mass and morphology have evolved as a result of both long-term adaptation and constraints of the taxonomic group over their long evolutionary history.
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China ; University of Chinese Academy of Sciences Beijing, 100039, China.
authors: Yongji
authors: Y
authors: Wang
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China ; University of Chinese Academy of Sciences Beijing, 100039, China.
authors: Jianjian
authors: J
authors: Wang
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China.
authors: Liming
authors: L
authors: Lai
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China.
authors: Lianhe
authors: L
authors: Jiang
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China.
authors: Ping
authors: P
authors: Zhuang
authors: Lushan Botanical Garden, Jiangxi Province and Chinese Academy of Sciences Jiujiang, Jiangxi Province, 332900, China.
authors: Lehua
authors: L
authors: Zhang
authors: Key Laboratory of Resource Plants, Beijing Botanical Garden, West China Subalpine Botanical Garden, Institute of Botany, Chinese Academy of Sciences Beijing, Xiangshan, China.
authors: Yuanrun
authors: Y
authors: Zheng
authors: Department of Biology, University of Kentucky Lexington, Kentucky, 40506.
authors: Jerry M
authors: JM
authors: Baskin
authors: Department of Biology, University of Kentucky Lexington, Kentucky, 40506 ; Department of Plant and Soil Sciences, University of Kentucky Lexington, Kentucky, 40546.
authors: Carol C
authors: CC
authors: Baskin
keywords: Altitude; Rhododendron; geographic variation; habitat; plant height; seed mass; seed morphology