Rapd Analysis of the Last Population of a Likely Florida Keys Endemic Cactus

The semaphore cactus in the Florida Keys bus until recently been considered a disjunct location of the Jamaican Opuntia spinosissima. Loss of all but one population in the Keys coupled with recent suggestions that the species should be taxonomically separated from the Jamaican cactus and is, therefore, a Florida Keys endemic, makes this population of conservation concern. Random amplified polymorphic DNA (RAPD) ana1.v.si.s was conducted on the remaining 12 individual large stems in the wild to determine whether this small population contains multiple genotypes. Other accessions of the cactus, mainly from private collections and from the Caribbean were also included. Analysis of 42 RAPD markers reveals that all Florida accessions are closely related, with unique genotypes being separated by dt~erences at only one to as many as jive polymorphic markers (2.4-11.9% of markers). Within the wild population. seven genoype.7 could be unique1.y identified. The Jamaican accession was separated from the Florida cacti by an average of 22 marker dt2erence.s (52.3% of the markers). The difference of the Florida accessions from the Jamaican accession by a large number of markers suggests possible species-level differentiation, providing additional supportive evidence that the Keys population may be one of the rarest and most threatened plants in the continental