Conservation and genetics of two Critically Endangered Hispaniolan palms: genetic erosion of Pseudophoenix lediniana in contrast to P. ekmanii

Abstract

The palm species Pseudophoenix ekmanii (endemic to the Dominican Republic) and P. lediniana (endemic to Haiti) are the only Critically Endangered species (sensu IUCN) of the genus. Results are presented of recent field research and population genetic studies targeting P. lediniana. The field research confirmed that wild plants of P. lediniana are restricted to a single population found along almost inaccessible and unstable limestone cliffs along a ravine in southern Haiti, near Jacmel in the Province of Ouest. The population is composed of six fragments with approximately 71 adults and 2 juveniles. No seedlings were located, and the population is under severe extinction threat because of landslides during the raining season, massive forest clearance, and burns for charcoal extraction and cropping of subsistence staple crops. Seven DNA microsatellite (SSR) loci were used to generate estimates of genetic variation of this species. Approximately one-third of all wild plants (21 individuals) were sampled. Only four of these SSR loci were polymorphic and population genetic coefficients showed that the population is highly inbred. Population genetics results for P. lediniana were compared with those previously published for P. ekmanii. Levels of genetic variation were quantified by number of polymorphic loci and observed heterozygosity. These values were much lower in P. ledinana than in P. ekmanii. The latter species is officially protected in a national park and has several populations, some much larger than that of the P. lediniana population. Differences concerning in situ conservation protection and population size might explain differences for levels of genetic variation between these two Critically Endangered species. Ex situ and in situ strategies for conservation are proposed.