Conservation Genetics

, Volume 17, Issue 6, pp 1269–1284 | Cite as

Analysis of mating system and genetic structure in the endangered, amphicarpic plant, Lewton’s polygala (Polygala lewtonii)

  • Joel F. Swift
  • Stacy A. Smith
  • Eric S. Menges
  • Burgund Bassüner
  • Christine E. Edwards
Research Article


Polygala lewtonii is a federally endangered, amphicarpic plant with a mixed mating system and three types of flowers: (1) aboveground, chasmogamous flowers (i.e., open-pollinated; CH), (2) aboveground, cleistogamous flowers (i.e., closed, selfing; CL) and (3) CL flowers on belowground stems (amphicarpy). Aboveground seeds are ant-dispersed, whereas belowground seeds are spaced across the length of the rhizome. Here, we collected individuals of P. lewtonii at both range-wide and fine geographic scales and genotyped them at 11 microsatellite loci. We analyzed patterns of genetic diversity and structure to understand: (1) the predominant mating system (selfing or outcrossing), (2) the movement of pollen and seeds across the landscape, and (3) the optimal strategy to conserve the full range of genetic variation. P. lewtonii reproduces predominantly by selfing or bi-parental inbreeding, but reproduction occurred through each of the three flower types. Some individuals produced by selfing/inbreeding were tightly clustered spatially, and were likely produced either by belowground flowers or by aboveground flowers with limited seed dispersal. Other selfed/inbred individuals were spatially separated (maximum of 15 m), and were likely produced by aboveground flowers followed by seed dispersal by ants. Fine-scale patterns of genetic structure indicate that some gene flow is occurring among aboveground CH flowers but both pollen and outcrossed seeds are moving limited distances (maximum of 0.5 km). Because genetic variation is structured at a fine spatial scale, protecting many populations is necessary to fully conserve the genetic variation in P. lewtonii. Conservation seed banking, if accompanied by research on seed germination requirements, may also contribute to the effective protection of genetic variation in P. lewtonii.


Amphicarpy Ant dispersal Conservation Genetic structure Mixed mating system Microsatellite Self-fertilization 



The authors would like to thank Dr. David Bogler for logistical support during the Missouri Botanical Garden Research Experience for Undergraduates program; the DNA analysis facility at Science Hill at Yale University for processing genetic samples; Carl Weekley, Stephanie Koontz, Jamie Peeler, Devon Picklum, David Zaya, Jennifer Navarra, Sarah Hicks, Lauren Sullivan, John Lowell, Kate Prengaman, and David Horton for assistance with field work; and David Boshier and two anonymous reviewers for comments on previous versions of this manuscript. This work was supported by the Florida Department of Agriculture and Consumer Services Division of Plant Industry (Grant number 020159) and the Research Experiences for Undergraduates Program of National Science Foundation (Grant number DBI-1157030).

Supplementary material

10592_2016_860_MOESM1_ESM.docx (133 kb)
Supplementary material 1 (DOCX 133 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2016

Authors and Affiliations

  • Joel F. Swift
    • 1
  • Stacy A. Smith
    • 2
  • Eric S. Menges
    • 2
  • Burgund Bassüner
    • 1
  • Christine E. Edwards
    • 1
  1. 1.Center for Conservation and Sustainable DevelopmentSt. LouisUSA
  2. 2.Plant Ecology ProgramArchbold Biological StationVenusUSA

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