RAPD analysis of South Pacific coconut palm populations

The South Pacific region represents a large potential genetic resource for improvement of coconut palms (Cocos nucifera L.). A study of the genetic diversity in the species was made in 1992-1993 by means of RAPD analysis on a representative sample from 17 distinct South Pacific coconut populations to characterize the germplasm present in the region. A moderate level of genetic diversity Was found, although very few RAPD markers were unique to specific populations. Approximately 60% of the observed diversity occurred within-populations, but this level varied between the various populations. This indicated the generally low but variable influence of gene migration between populations, the establishment of populations by few individuals that comprised a fraction of the genetic variation of their parental populations (founder effects), and subsequent selection by the local human population. Although the coconut populations of the region generally displayed a pattern of continuous variation, this continuum could be divided into discrete groups by cluster analysis. This division comprised a southern group of populations, a northern-eastern group, and single-population groups from the Marquesas and Hawaii groups. The population from Rennell Island diverged from the main genetic continuum, apparently because of isolation and artificial selection. Collection and conservation strategies have been devised for coconut germplasm in the South Pacific region based on existing genetic diversity.