Overexploitation and anthropogenic disturbances threaten the genetic diversity of an economically important neotropical palm

Abstract

The Caatinga biome is one of the largest areas of the South American seasonally dry tropical forest that has been severely affected by unsustainable natural resource use. Furthermore, the biome has been identified as an ecologically sensitive region that is particularly susceptible to climate changes. One of the most economically important native palm tree for traditional communities from the semi-arid Caatinga is the carnauba palm, Copernicia prunifera, which offers diverse natural resources, yet its natural populations suffer intense exploitation. To inform conservation and population management strategies, we sought to determine if remaining natural populations of this species in an intensively exploited area in Northeast Brazil displayed evidence of negative genetic impacts because of exploitation and how this might interact with expected environmental changes. Mantel’s test revealed a positive and significant correlation between geographic and genetic distances, suggesting natural populations are structured by isolation by distance, while also experiencing genetic barriers as identified through Monmonier's algorithm. The studied populations showed evidence of genetic bottlenecks, while future climate scenarios suggest that potentially suitable habitats for C. prunifera within its native range will be reduced. Significant genetic differentiation among populations resulted in three distinct genetic groups which are consistent with ecological niche modelling. In addition to the need for in situ conservation of C. prunifera populations to minimize the loss of important alleles, the creation of germplasm banks for ex situ conservation and strategies for developing planted productive forests are urgently required to maintain natural populations and ensure sustainability resources for traditional communities.