Coevolutionary elaboration of pollination-related traits in an alpine ginger (Roscoea purpurea) and a tabanid fly in the Nepalese Himalayas.
Geographical variation in the interacting traits of plant-pollinator mutualism can lead to local adaptive differentiation. We tested Darwin's hypothesis of reciprocal selection as a key driving force for the evolution of floral traits of an alpine ginger (Roscoea purpurea) and proboscis length of a tabanid fly (Philoliche longirostris). We documented the pattern of trait variation in R. purpurea and P. longirostris across five populations. At each site, we quantified pollinator-mediated selection on floral display area, inflorescence height and corolla length of R. purpurea by comparing selection gradients for flowers exposed to natural pollination and to supplemental hand pollination. Reciprocal selection between plant and fly was examined at two sites via the relationship between proboscis length and nectar consumption (fly benefit) and corolla length and pollen deposition (plant benefit). Local corolla tube length was correlated with local fly proboscis length among the five sites. We found strong linear selection imposed by pollinators on corolla tube length at all sites, but there was no consistent relationship of fitness to inflorescence height or floral display area. Selection between corolla length and proboscis length was reciprocal at the two experimental sites examined. The geographical pattern of trait variation and the evidence of selection is consistent with a mosaic of local, species-specific reciprocal selection acting as the major driving force for the evolution of corolla length of R. purpurea and proboscis length of P. longirostris.
Plant Evolutionary Ecology Research Group, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan, 666303, China.|University of Chinese Academy of Sciences, Beijing, 100039, China.|Tribhuvan University, Department of Botany, Prithvi Narayan Campus, Pokhara, Nepal.
Babu Ram
BR
Paudel
School of Media and Communication, RMIT University, Melbourne, Victoria, 3001, Australia.|Faculty of Information Technology, Monash University, Melbourne, Victoria, 3800, Australia.
Mani
0000-0002-6165-8418
M
Shrestha
School of Biological Sciences, Monash University, Melbourne, Victoria, 3800, Australia.
Martin
M
Burd
Land Resources and Environmental Sciences, Montana State University, Bozeman, MT, 59715, USA.
Subodh
S
Adhikari
Plant Evolutionary Ecology Research Group, Key Laboratory of Tropical Forest Ecology, Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Menglun Town, Mengla County, Yunnan, 666303, China.
Yong-Shuai
YS
Sun
Laboratory of Ecology and Evolutionary Biology, State Key Laboratory for Conservation and Utilization of Bio-Resources in Yunnan, Yunnan University, Kunming, Yunnan, 650091, China.
Qing-Jun
QJ
Li
D000818:Animals; D005075:Biological Evolution; D004175:Diptera / Q000502:physiology*; D017753:Ecosystem; D035264:Flowers / Q000033:anatomy & histology / Q000502:physiology; D005843:Geography; D020939:Zingiber officinale / Q000502:physiology*; D009390:Nepal; D054817:Pollination / Q000502:physiology*; D019655:Quantitative Trait, Heritable
Philoliche longirostris; Roscoea; alpine ginger; coevolution; phenotypic selection; pollination