Conservation Genetics

, Volume 9, Issue 2, pp 411–418 | Cite as

Optimal sampling strategies for capture of genetic diversity differ between core and peripheral populations of Picea sitchensis (Bong.) Carr

  • Washington J. GapareEmail author
  • Alvin D. Yanchuk
  • Sally N. Aitken
Research Article


In previous studies we reported that while core populations of Sitka spruce [Picea sitchensis (Bong.) Carr] have little within-population genetic structure, peripheral populations are strongly spatially structured at distances up to 500 m. Here we explore the implications of this difference in structure on ex situ gene conservation collections and estimates of genetic diversity from research collections. We test the effects of varying the number of individuals sampled and the total area they are sampled across on capture of neutral genetic variation in collections from core, continuous versus peripheral, disjunct populations. Bivariate response surface analysis of genetic marker data for eight sequence tagged site loci from core and peripheral populations suggest that a population sample from 150 trees covering at least 225 ha would be adequate for capturing 95% of the genetic diversity (as measured by allelic richness or expected heterozygosity) in core populations. However, a larger sample of 180 individuals from an area of at least 324 ha is needed in peripheral populations to capture the same proportion of standing variation because of stronger within-population spatial genetic structure. Standard population sampling protocols for estimating among and within-population genetic diversity would significantly underestimate the within-population allelic richness and expected heterozygosity of peripheral but not core populations, potentially leading to poor representation of genetic variation in peripheral populations as well as erroneous conclusions about their genetic impoverishment.


Genetic diversity Core populations Peripheral populations Sampling strategies Ex situ gene conservation 



We would like to thank Don Pigott, Jim Herbers, Lynn Norton for their help with the field component of this study; and Joanne Tuytel for help in the laboratory. Special thanks to Drs. Tongli Wang and Pia Smets at UBC for assistance with the bivariate response surface analysis. We also thank Dr. Kermit Ritland for his initial review of this paper when it was part of the Ph.D. thesis for the senior author. This work was initially funded by Forest Renewal British Columbia and subsequently by the Forest Investment Account, British Columbia, Canada, through the Forest Genetics Council to the Centre for Forest Gene Conservation at the University of British Columbia. We wish to thank the anonymous reviewers for valuable comments and suggestions on an earlier version of the manuscript.


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Copyright information

© Springer Science+Business Media B.V. 2007

Authors and Affiliations

  • Washington J. Gapare
    • 1
    • 3
    Email author
  • Alvin D. Yanchuk
    • 2
  • Sally N. Aitken
    • 1
  1. 1.Centre for Forest Gene ConservationUniversity of British ColumbiaVancouverCanada
  2. 2.Ministry of Forests, Research Branch, British ColumbiaVictoriaCanada
  3. 3.Ensis (Ensis is a joint venture between CSIRO FFP P/L and SCION Australasia P/L), CSIRO Forestry and Forest ProductsKingstonAustralia

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