Conservation Genetics

, Volume 16, Issue 2, pp 443–457 | Cite as

Examining the genetic integrity of a rare endemic Colorado cactus (Sclerocactus glaucus) in the face of hybridization threats from a close and widespread congener (Sclerocactus parviflorus)

  • Anna L. Schwabe
  • Jennifer Ramp Neale
  • Mitchell E. McGlaughlin
Research Article


Natural interspecific hybridization within plants is relatively common and plays an important evolutionary role. Hybridization between rare and common taxa is of concern due to questions of protection status related to hybrids. However, field based identification of hybrid plants can be challenging. Sclerocactus glaucus (Cactaceae), the Colorado hookless cactus, is protected under the Endangered Species Act and has a small range around Grand Junction, Colorado, where populations are threatened by anthropogenic activities. Field biologists frequently observe S. glaucus populations containing individuals with hooked spines that are thought to be either hybrids or individuals of a closely related, parapatrically distributed species, Sclerocactus parviflorus. We used 13 nuclear microsatellites and two chloroplast DNA sequence regions to examine genetic diversity and structure within S. glaucus and potential hybridization with S. parviflorus. The two species were found to be genetically distinct based on microsatellites (average FST = 0.14 among species) and chloroplast sequence data (no shared haplotypes among species). Evidence of minimal hybridization was documented (5.7 % of sampled S. glaucus individuals with >10 % S. parviflorus signal). Hybrid individuals did not show a clear geographic or morphological pattern. Sclerocactus glaucus populations contained significant genetic structure falling into north and south groups associated with two separate river drainages. Overall, genetic integrity of sampled S. glaucus populations is intact, with relatively high diversity (Ho = 0.47, He = 0.66) and low levels of inbreeding (FIS = 0.28), indicating management should focus on protecting existing populations and preventing movement of material among genetically distinct regions.


Sclerocactus Conservation Hybridization Cactaceae Microsatellite Diversity Genetic structure 



This research was funded by a US Fish and Wildlife Service Small Grants for Plants award to Jennifer Ramp Neale and Mitchell E. Mc Glaughlin, a University of Northern Colorado Summer Support Initiative Research Grant to Mitchell E. McGlaughlin, and awards to Anna L. Schwabe from the University of Northern Colorado and the Colorado Native Plant Society Myrna P. Steinkamp fund. Thank you to Michelle DePrenger-Levin for her work in the field as well as her help with statistical analyses. We are grateful to Gina Glenne, Alicia Langton, Mary Goshorn, Anna Lincoln, Panayoti Kelaidis and field volunteers and staff from the Bureau of Land Management, US Fish and Wildlife Service, and Denver Botanic Gardens for field assistance.

Supplementary material

10592_2014_671_MOESM1_ESM.docx (90 kb)
Supplementary material 1 (DOCX 89 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2014

Authors and Affiliations

  • Anna L. Schwabe
    • 1
  • Jennifer Ramp Neale
    • 1
  • Mitchell E. McGlaughlin
    • 2
  1. 1.Denver Botanic GardensDenverUSA
  2. 2.School of Biological SciencesUniversity of Northern ColoradoGreeleyUSA

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