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Title: Can a botanic garden cycad collection capture the genetic diversity in a wild population?

Author
item GRIFFITH, M - Montgomery Botanical Center
item CALONJE, M - Florida International University
item Meerow, Alan
item TUT, FREDDY - Belize Agricultural Health Authority
item KRAMER, ANDREA - Chicago Botanical Garden
item HIRD, ABBY - Botanical Research Institute
item MAGELLAN, TRACY - Botanical Research Institute
item HUSBY, CHAD - Montgomery Botanical Center

Submitted to: International Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/14/2015
Publication Date: 4/2/2015
Citation: Griffith, M.P., Calonje, M., Meerow, A.W., Tut, F., Kramer, A.T., Hird, A., Magellan, T.M., Husby, C.E. 2015. Can a botanic garden cycad collection capture the genetic diversity in a wild population?. International Journal of Plant Science. 176:1-10.

Interpretive Summary: Conservation of plant species often requires ex situ (off-site) cultivation of living collections. Cycads constitute the most imperiled major group of plants, and ex situ collections are an important part of conservation planning for this group, given seed propagation problems, difficulties with tissue culture, and ongoing in situ threats. Very little is known about the genetics of ex situ conservation collections of cycads. Thus, this study seeks to illuminate how well an ex situ collection of a cycad can capture the genetic diversity in a wild population. A model species, Zamia decumbens, was chosen based on geographic isolation and detailed census knowledge, which allowed near-total sampling of in situ plants. Overall, 375 in situ plants were compared to 205 ex situ plants via 10 microsatellite DNA markers. Genetic distance analysis shows high identity of the ex situ collections to their in situ source populations, as well as clustering of ex situ progeny with their siblings, with strong identity to their respective mother plant. Capture of the ix situ genetic diversity increases as number of ex situ plants maintained increases, but with a diminishing rate of increase. These data demonstrate that botanic garden collections can better conserve the genetic diversity of in situ cycad populations, if four recommendations are followed: (1) use the species biology to inform the collecting strategy; (2) manage each population separately; (3) collect and maintain multiple accessions; and (4) collect over multiple years.

Technical Abstract: Conservation of plant species often requires ex situ (off-site) cultivation of living collections. Cycads constitute the most imperiled major group of plants, and ex situ collections are an important part of conservation planning for this group, given seed recalcitrance, difficulties with tissue culture, and ongoing in situ threats. Very little is known about the genetics of ex situ conservation collections of cycads. Thus, this study seeks to illuminate how well an ex situ collection of a cycad can capture the diversity in a wild population. A model species, Zamia decumbens, was chosen based on geographic isolation and detailed census knowledge, which allowed near-total sampling of in situ plants. Overall, 375 in situ plants were compared to 205 ex situ plants via 10 microsatellite markers. Genetic distance analysis shows high fidelity of the ex situ collections to their in situ source populations, as well as clustering of ex situ progeny by accession, with strong identity to their respective mother plant. Structured re-sampling of allele capture from the in situ populations by the ex situ collection show allele capture increases as number of ex situ plants maintained increases, but with a diminishing rate of increase. These data demonstrate that botanic garden collections can better conserve the genetic diversity of in situ cycad populations, if four recommendations are followed: (1) use the species biology to inform the collecting strategy; (2) manage each population separately; (3) collect and maintain multiple accessions; and (4) collect over multiple years.