Genetic Resources and Crop Evolution

, Volume 54, Issue 4, pp 837–848 | Cite as

Capturing genetic diversity of wild populations for ex situ conservation: Texas wild rice (Zizania texana) as a model

  • Christopher M. Richards
  • Michael F. Antolin
  • Ann Reilley
  • Jackie Poole
  • Christina Walters
Original Paper


Genebanks complement other conservation programs because they preserve genetic diversity needed for future breeding and restoration. We evaluated efficiency of capturing genetic diversity, using endangered Zizania texana (Texas wild rice) as a model for plants with recalcitrant seeds. This perennial aquatic grass is restricted to 4 km of the San Marcos River in Texas. An early conservation collection included plants from stands throughout the river, based on the assumption stands would be unique genotypes. Using microsatellite markers, we found that genetic diversity was concentrated in five of 15 large, demographically stable stands; 96 stands smaller than 2 m2 contributed no unique alleles. High heterozygosity and few duplicate genotypes suggested that sexual reproduction occurs more often than presumed. Simulations of stratified sampling of large stands captured all alleles in only 45 individuals, while random sampling along the river captured much less diversity. The early conservation collection captured as much diversity as expected from random sampling. Texas wild rice stands resemble a mainland-island metapopulation; our analyses suggest that stratified sampling maximizes genetic diversity for this population dynamic. Demographic and genetic information is important for validating the design of efficient ex situ collections and guiding in situ conservation.

Key words

Stratified sampling Allelic richness Conservation genetics Genetic structure Zizania texana 


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  1. Brown AHD, Briggs JD (1991) Sampling strategies for genetic variation in ex situ collections of endangered plant species. In: Falk DA, Holsinger KE (eds) Genetics and conservation of rare plants. Oxford University Press, New York, pp 99–119Google Scholar
  2. Brown AHD, Hardner CM (2000) Sampling the gene pools of forest trees for ex situ conservation. In: Young A, Boyle TJB, Boshier D (eds) Forest conservation genetics: principles and practice. CABI Publishing, Wallingford, pp 185–196Google Scholar
  3. Caujape-Castells J, Pedrola-Monfort J (2004) Designing ex-situ conservation strategies through the assessment of neutral genetic markers: application to the endangered Androcymbium gramineum. Conserv Genet 5:131–144CrossRefGoogle Scholar
  4. Cavers S, Navarro C, Lowe AJ (2004) Targeting genetic resource conservation in widespread species: a case study of Cedrela odorata L. Forest Ecol Manage 197:285–294CrossRefGoogle Scholar
  5. Ceska JF, Affolter JM, Hamrick JL (1997) Developing a sampling strategy for Baptisia arachnifera based on allozyme diversity. Conserv Biol 11:1133–1139CrossRefGoogle Scholar
  6. Crandall KA, Bininda-Emonds ORP, Mace GM, Wayne RK (2000) Considering evolutionary processes in conservation biology. Trends Ecol Evol 15:290–295PubMedCrossRefGoogle Scholar
  7. Emery WHP (1977) Current status of Texas wild rice. The Southwestern Nat 22:393–394Google Scholar
  8. Goudet J (1995). FSTAT (vers. 1.2): A computer program to calculate F-statistics. J Heredity 86:485–486Google Scholar
  9. Gouesnard B, Bataillon TM, Decoux G, Rozale C, Schoen DJ, David JL (2001) MSTRAT: An algorithm for building germplasm core collections by maximizing allelic or phenotypic richness. J Heredity 92:93–94CrossRefGoogle Scholar
  10. Hastings A, Harrison S (1994) Metapopulation dynamics and genetics. Ann Rev Ecol Syst 25:167–188CrossRefGoogle Scholar
  11. Hayes PM, Stucker RE, Wandrey GG (1989) The domestication of American wild-rice (Zizania palustris, Poaceae). Econ Bot 43:203–214Google Scholar
  12. Hedrick PW (2004) Genetics of populations, 3rd edn. Jones and Bartlett Publishers, Sudbury, MAGoogle Scholar
  13. Hong TD, Linington SH, Ellis RH (1998) Compendium of Information on Seed Storage Behavior, two volumes. Royal Botanic Gardens, Kew, UKGoogle Scholar
  14. Jin Y, Zhang W-J, Fu D-X, Lu B-R (2003) Sampling strategy within a wild soybean population based on its genetic variation detected by ISSR markers. Acta Bot Sinica 45:995–1002Google Scholar
  15. Lewis PO, Zaykin D (2001). GDA User’s manual. Department of Ecology and Evolutionary Biology, University of Connecticut.
  16. McKhann HI, Camilleri C, Berard A, Bataillon T, David JL, Reboud X, Le Corre V, Caloustian C, Gut IG, Brunel D (2004) Nested core collections maximizing genetic diversity in Arabidopsis thaliana. Plant J 38:193–202PubMedCrossRefGoogle Scholar
  17. Moritz C (2002) Strategies to protect biological diversity in the evolutionary processes that sustain it. Syst Biol 51:238–254PubMedCrossRefGoogle Scholar
  18. Neel MC, Cummings MP (2003) Effectiveness of conservation targets in capturing genetic diversity. Conserv Biol 17:219–229CrossRefGoogle Scholar
  19. Nei M (1987) Molecular evolutionary genetics. Columbia University Press, NYGoogle Scholar
  20. Petit RJ, El Mousadik A, Pons O (1998) Identifying populations for conservation on the basis of genetic markers. Conserv Biol 12:844–855CrossRefGoogle Scholar
  21. Poole J, Bowles DE (1999) Habitat characterization of Texas wild-rice (Zizania texana Hitchcock), an endangered aquatic macrophyte from the San Marcos River, TX, USA. Aquat Conserv: Marshes Freshwater Ecosyst 9:291–302CrossRefGoogle Scholar
  22. Power P, Fonteyn PJ (1995) Effects of oxygen concentration and substrate on seed germination and seedling growth of Zizania texana (Texas wildrice). The Southwestern Nat 40:1–4Google Scholar
  23. Power P (1996) Reintroduction of Texas wildrice (Zizania texana) in Spring Lake: some important environmental and biotic considerations. In: Proceedings of the Second Conference on Southwestern rare and endangered plants on 1995 September 11–14 in Flagstaff, AZ. General Technical Report RM-GTR-283. USDA Forest Service Rocky Mountain Forest and Range Experiment Station, Fort Collins COGoogle Scholar
  24. Power P (1997) Moisture, seeds and reproductive failure in Texas wildrice (Zizania texana). The Southwestern Nat 42:435–440Google Scholar
  25. Richards CM, Reilley A, Touchell DH, Antolin MF, Walters C (2004) Microsatellite primers for Texas wild rice (Zizania texana), and a preliminary test of the impact of cryogenic storage on allele frequency at these loci. Conserv Genet 5:853–859CrossRefGoogle Scholar
  26. Schemske DW, Husband BC, Ruckelshaus MH, Goodwillie C, Parker IM, Bishop JM (1994) Evaluating approaches to the conservation of endangered plants. Ecology 75:584–606CrossRefGoogle Scholar
  27. Schoen DJ, Brown AHD (1991) Intraspecific variation in population gene diversity and effective population size correlates with the mating system in plants. Proc Natl Acad Sci USA 88:4494–4497PubMedCrossRefGoogle Scholar
  28. Schoen DJ, Brown AHD (1993) Conservation of allelic richness in wild crop relatives is aided by assessment of genetic markers. Proc Natl Acad Sci USA 90:10623–10627PubMedCrossRefGoogle Scholar
  29. Schoen DJ, Brown AHD (1995) Maximising genetic diversity in core collections of wild relatives of crop species. In: Hodgkin T, Brown AHD, van Hintum ThJL, Morales EAV (eds) Core Collections of Plant Genetic Resources. John Wiley & Sons, Chichester, UK, pp. 55–76Google Scholar
  30. Schoen DJ, Brown AHD (2001) The conservation of wild plant species in seed banks. BioScience 51:960–966CrossRefGoogle Scholar
  31. Shands HL (1991) Complementarity of in situ and ex situ germplasm conservation from the standpoint of the future user. Israel J Bot 40:521–528Google Scholar
  32. Sokal RR, Rohlf FJ (1995) Biometry, 3rd edn. W.H. Freeman and Company, New YorkGoogle Scholar
  33. Terrell EE, Emery WHP, Beaty HE (1978) Observations on Zizania texana (Texas Wild Rice), an endangered species. Bull Torrey Botanical Club 105:50–57CrossRefGoogle Scholar
  34. Vaughan JE (1986) Populations and autecological assessment of Zizania texana Hitchc. (Poaceae) in the San Marcos River. M.Sc. Thesis, Southwest Texas State University, San Marcos, TXGoogle Scholar
  35. Walters C, Touchell DH, Power P, Wesley-Smith J, Antolin MF (2002) A cryopreservation protocol for embryos of the endangered species Zizania texana. CryoLetters 23:291–298PubMedGoogle Scholar
  36. Walters C (2004) Principles for preserving germplasm in genebanks. In: Guerrant E, Havens K, Maunder M (eds) Ex situ plant conservation: supporting species survival in the wild. Island Press, Covelo, CA, pp 442–453Google Scholar
  37. Young AG, Hill JH, Murray BG, Peakall R (2002) Breeding system, genetic diversity and clonal structure in the sub-alpine forb Rutidosis leioepis F. Muell. (Asteraceae). Biol Conserv 106:71–78CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, Inc. 2006

Authors and Affiliations

  • Christopher M. Richards
    • 1
  • Michael F. Antolin
    • 2
  • Ann Reilley
    • 1
  • Jackie Poole
    • 3
  • Christina Walters
    • 1
  1. 1.USDA/ARS National Center for Genetic Resources PreservationFort CollinsUSA
  2. 2.Department of BiologyColorado State UniversityFort CollinsUSA
  3. 3.Texas Parks & WildlifeAustinUSA

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