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.

Population genomics of the neotropical palm Copernicia prunifera (Miller) H. E. Moore: Implications for conservation

“…Although C . prunifera is not listed as an endangered species, the expansion of agricultural activities over time has contributed to a reduction in its natural population [ 17 ]. Therefore, conservation measures are necessary to minimize the additional loss of alleles and to ensure the maintenance of genetic resources.…”

“…The main product of economic value obtained from this tree is carnaúba wax, which is extracted from young leaves and is of interest in the pharmaceutical and automotive industries [ 16 ]. Carnaúba populations suffer from intense exploitation because the method used to extract carnauba wax, which consists of practically removing all the leaves of the plant to obtain ceriferous powder [ 17 ].…”

“…prunifera populations show signs of intense exploitation with visible signs of anthropogenicity, such as fire, extraction and cutting of leaves, soil impacted by livestock, and low or absence of regeneration ( Fig 1 ). In addition, anthropogenic disturbances in the last century, mainly due to deforestation, agricultural expansion, and modernization of agriculture, have led to a rapid decline in these populations [ 17 ].…”

“…Genetic diversity studies based on molecular markers of natural populations of C . prunifera in tropical areas such as Caatinga and Restinga are still scarce [ 17 , 28 – 30 ]. In addition, no studies on C .…”

“…Genetic diversity studies based on molecular markers of natural populations of C. prunifera in tropical areas such as Caatinga and Restinga are still scarce [17,[28][29][30]. In addition, no studies on C. prunifera have applied next-generation sequencing technology for data acquisition in population genomics.…”