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Conservation Genetics

, Volume 10, Issue 1, pp 115–126 | Cite as

High genetic divergence characterizes populations of the endemic plant Lithophragma maximum (Saxifragaceae) on San Clemente Island

  • M. Steven Furches
  • L. E. Wallace
  • K. Helenurm
Research Article

Abstract

Narrowly-ranging species frequently harbor less genetic variability relative to widespread relatives and face graver extinction threats due to the heightened impacts of stochastic events on ecological and genetic diversity. In this study, we examined the impact of historical and current threats to the maintenance of genetic variation in Lithophragma maximum (Saxifragaceae), a perennial herb endemic to San Clemente Island, California. This species exists as small populations confined to canyons along 4 km of the southeast coastline of the island. In 15 populations analyzed with 10 microsatellite markers, we identified an average of 2.05 alleles per locus and 58.7% polymorphic loci. Significant departures from Hardy–Weinberg equilibrium existed in six populations; five of these exhibited heterozygote deficiency. Bayesian inference of genetic structure indicated a significant amount of structure among populations and canyons and infrequent gene flow even over very short distances. We also identified a significant and positive correlation between genetic and geographic distances, indicative of isolation by distance. There was no evidence of recent bottlenecks in any of the sampled populations, but older bottlenecks were detected in two populations. These results suggest that populations of L. maximum have historically been small and isolated, which is likely due to the rugged habitat in which this species occurs and limited pollen and seed dispersal. Given the high degree of structure observed across populations, we suggest that conservation efforts should focus on preserving populations in multiple canyons, maintaining large population sizes to preserve genetic variation, and controlling the spread of invasive species in areas where L. maximum occurs.

Keywords

Conservation genetics Microsatellites Lithophragma Endemic species Channel Islands 

Notes

Acknowledgements

We thank Steve Burckhalter and Steve Junak for collection of specimens on San Clemente Island and Mitchell McGlaughlin for assistance with DNA extractions. This research was supported by the Natural Resources Office, Staff Civil Engineer, Naval Air Station, North Island, San Diego, California, National Science Foundation/EPSCoR Grant No. 0091948 and by the State of South Dakota.

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Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • M. Steven Furches
    • 1
  • L. E. Wallace
    • 2
  • K. Helenurm
    • 3
  1. 1.Department of Ecology and Evolutionary BiologyUniversity of Tennessee – KnoxvilleKnoxvilleUSA
  2. 2.Department of Biological SciencesMississippi State UniversityMississippi StateUSA
  3. 3.Department of Biological SciencesUniversity of South DakotaVermillionUSA

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