A tale of two cacti: studies in Astrophytum asterias and Lophophora williamsii

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dc.contributor.advisor Manhart , James R . en_US
dc.contributor.committeeMember DeWitt , Thomas en_US
dc.creator Terry , Martin Kilman en_US
dc.date.accessioned 2007 -04 -25T20 :16 :47Z
dc.date.accessioned 2014 -02 -19T19 :28 :18Z
dc.date.available 2007 -04 -25T20 :16 :47Z
dc.date.available 2014 -02 -19T19 :28 :18Z
dc.date.created 2005 -12 en_US
dc.date.issued 2007 -04 -25T20 :16 :47Z
dc.identifier.uri http : / /hdl .handle .net /1969 .1 /5023
dc.description.abstract Astrophytum asterias (star cactus ) and Lophophora williamsii (peyote ) are sympatric species in the Tamaulipecan thornscrub of South Texas and adjacent Mexico . Peyote has been excavated from two archaeological sites : Shumla Caves , Texas , and CM -79 in Coahuila . We report new radiocarbon dates : a mean of 5195 ? ? ? ? 20 14C years BP for the Shumla Caves specimens , and 835 ? ? ? ? 35 14C years BP for the CM -79 specimen . The Shumla Caves specimens were not intact peyote tops , but manufactured effigies thereof . Published data on the geographic ranges of L . williamsii and A . asterias are of varying quality and accuracy . We report the results of extensive research to document extant U .S . populations by county , drawing specific conclusions about where each species currently occurs , where its occurrence is uncertain and where it is unlikely , based on herbarium specimens , verifiable reports in the primary literature and interviews with knowledgeable individuals . Dwindling of populations of peyote is partly due to improper harvesting , namely cutting off the top of the plant so deeply below ground level that the plant is unable to regenerate new stems , and consequently dies . We describe the anatomy of the cactus shoot (stem ) and root , and suggest how this new knowledge can be utilized to determine "how deep is too deep" to cut if harvesting of peyote is to be done sustainably . We report the first population genetics study on endangered A . asterias , with five microsatellite markers in populations sampled at four locations in South Texas . A battery of tests and measurements indicated that in most populations heterozygosity was high , F -statistics were low , and Nm was >1 . With one exception , these populations appear not to be undergoing excessive inbreeding , despite small population sizes . Data from two L . williamsii microsatellite loci are presented . L . williamsii , which reproduces autogamously , exhibits a single homozygous genotype within a given population . West Texas L . williamsii plants differ from South Texas plants in the identity of the single allele (or single genotype ) at each locus . The ability of microsatellite markers to separate West Texas from South Texas plants suggests utility of microsatellites for infraspecific taxonomic studies in Lophophora . en_US
dc.format.extent 3847592 bytes
dc.format.medium electronic en_US
dc.format.mimetype application /pdf
dc.language.iso en _US en_US
dc.publisher Texas A &M University en_US
dc.subject Astrophytum asterias en_US
dc.title A tale of two cacti : studies in Astrophytum asterias and Lophophora williamsii en_US
dc.type Book en
dc.type.genre Electronic Dissertation en_US
dc.type.material text en_US
dc.format.digitalOrigin born digital en_US


A tale of two cacti: studies in Astrophytum asterias and Lophophora williamsii. Available electronically from http : / /hdl .handle .net /1969 .1 /5023 .

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