Gene flow and inbreeding depression inferred from fine-scale genetic structure in an endangered heterostylous perennial, Primula sieboldii

Authors

  • FUMIKO ISHIHAMA,

    Corresponding author
    1. Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113–8657, Japan,
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  • SANEYOSHI UENO,

    1. Genome Analysis Laboratory, Department of Forest Genetics, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305–8687, Japan
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  • YOSHIHIKO TSUMURA,

    1. Genome Analysis Laboratory, Department of Forest Genetics, Forestry and Forest Products Research Institute, Tsukuba, Ibaraki 305–8687, Japan
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  • IZUMI WASHITANI

    1. Graduate School of Agricultural and Life Sciences, University of Tokyo, 1-1-1 Yayoi, Bunkyo, Tokyo 113–8657, Japan,
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F. Ishihama, Fax: + 83-3-5841-8916; E-mail: isihama7@dolphin.c.u-tokyo.ac.jp

Abstract

We estimated the gene dispersal distance and the magnitude of inbreeding depression from the fine-scale genetic structure in the endangered heterostylous perennial Primula sieboldii. We indirectly estimated the neighbourhood size (Nb) and the standard deviation of gene dispersal distance (σg) from the detected genetic structure by using 10 microsatellite markers. We also estimated the fitness reduction in mating among neighbouring individuals caused by biparental inbreeding according to the genetic structure. We found clear fine-scale genetic structure (a significantly positive kinship coefficient within 42.3 m), and the indirect estimates of σg and Nb were 15.7 m and 50.9, respectively. These indirect estimates were similar to the direct estimates (18.4 m and 44.0). The slightly larger indirect estimate of Nb may reflect that inbreeding depression and genetic structure or rare long-distance dispersal that were overlooked in the direct estimate have elongated the long-term average of gene dispersal distance. P. sieboldii is also likely to suffer about 19% fitness reduction in progenies from mating among individuals 5 m apart. Our results suggest that biparental inbreeding and genetic structure can affect the range of gene dispersal and seed reproductive success in P. sieboldii.

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