Spatial genetic structure and restricted gene flow in a functionally dioecious fig, <Emphasis Type="Italic">Ficus pumila</Emphasis> L. var. <Emphasis Type="Italic">pumila</Emphasis> (Moraceae) |
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Authors: | Rong Wang Bin Ai Bang-Quan Gao Shuo Yu Yuan-Yuan Li Xiao-Yong Chen |
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Institution: | (1) Department of Environmental Sciences, Shanghai Key Laboratory for Ecological Processes and Restoration, East China Normal University, Shanghai, 200062, China;(2) Tiantong National Observation Station for Forest Ecosystems, Shanghai, 200062, China |
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Abstract: | The mutualism between fig plants and fig wasps has been recognized as one of the most specialized systems of symbiosis. Figs
are pollinated by their highly specific pollinating fig wasps, and the pollinating fig wasps are raised within the syconia
of figs. Recent studies indicated a difference between monoecious and dioecious figs in the dispersal range of pollinating
wasps, which has potential consequences for gene flow. In this study, we detected the gene-flow pattern of the dioecious climbing
fig, Ficus pumila L. var. pumila, at both local and regional scales. At the local scale, spatial autocorrelation analysis indicated strong genetic structure
at short distances, a pattern of limited gene flow. This result was also supported by a high inbreeding coefficient (F
IS = 0.287) and significant substructuring (F
ST = 0.060; P < 0.001). Further analysis indicated that the effective gene dispersal range was 1,211 m, and the relative contribution of
seed dispersal was smaller than that of pollen dispersal. The inferred effective range of pollen dispersal ranged from 989
to 1,712 m, while the effective seed dispersal range was less than 989 m. Lack of long-distance dispersal agents may explain
the limited seed dispersal. The high density of receptive fig trees was the most likely explanation for limited pollen dispersal,
and the position of syconia and relatively low wind speed beneath the canopy may contribute to this phenomenon. At the regional
scale, significant negative correlations (kinship coefficient F
ij
ranging from −0.038 to −0.071) existed in all comparisons between the studied population and other populations, and the assignment
test grouped almost all individuals of the studied population into a distinct cluster. Asynchronous flowering on the regional
scale, which provides a barrier for the pollinating wasps to fly from the studied population to the other populations, is
probably responsible for the limited gene flow on the regional scale. |
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Keywords: | Assignment test Ficus pumila L var pumila Microsatellites Pollen and seed dispersal Spatial genetic structure |
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