Taxonomic similarity does not predict necessary sample size for ex situ conservation: A comparison among five genera

Sean Hoban*, Taylor Callicrate, John Clark, Susan Deans, Michael Dosmann, Jeremie Fant, Oliver Gailing, Kayri Havens, Andrew L. Hipp, Priyanka Kadav, Andrea T. Kramer, Matthew Lobdell, Tracy Magellan, Alan W. Meerow, Abby Meyer, Margaret Pooler, Vanessa Sanchez, Emma Spence, Patrick Thompson, Raakel ToppilaSeana Walsh, Murphy Westwood, Jordan Wood, M. Patrick Griffith

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Scopus citations


Effectively conserving biodiversity with limited resources requires scientifically informed and efficient strategies. Guidance is particularly needed on how many living plants are necessary to conserve a threshold level of genetic diversity in ex situ collections. We investigated this question for 11 taxa across five genera. In this first study analysing and optimizing ex situ genetic diversity across multiple genera, we found that the percentage of extant genetic diversity currently conserved varies among taxa from 40% to 95%. Most taxa are well below genetic conservation targets. Resampling datasets showed that ideal collection sizes vary widely even within a genus: one taxon typically required at least 50% more individuals than another (though Quercus was an exception). Still, across taxa, the minimum collection size to achieve genetic conservation goals is within one order of magnitude. Current collections are also suboptimal: they could remain the same size yet capture twice the genetic diversity with an improved sampling design. We term this deficiency the ‘genetic conservation gap’. Lastly, we show that minimum collection sizes are influenced by collection priorities regarding the genetic diversity target. In summary, current collections are insufficient (not reaching targets) and suboptimal (not efficiently designed), and we show how improvements can be made.

Original languageEnglish (US)
Article number20200102
JournalProceedings of the Royal Society B: Biological Sciences
Issue number1926
StatePublished - May 13 2020


  • Botanic gardens
  • Conservation planning
  • Ex situ conservation
  • Genetic diversity
  • Seed banks
  • Trees

ASJC Scopus subject areas

  • Agricultural and Biological Sciences(all)
  • Environmental Science(all)
  • Immunology and Microbiology(all)
  • Biochemistry, Genetics and Molecular Biology(all)


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