Contrasting cpDNA Variation in Two Indonesian Endemic Lowland Dipterocarp Species and Implications for their Conservation

Abstract

Shorea javanica (Dipterocarpaceae) is an economically important dammar-producing tree, endemic to the tropical lowland forests of Sumatra and Java, Indonesia. However, its total population size is limited and this species is endangered. Shorea selanica is one of the very limited numbers of species in genus Shorea (Dipterocarpaceae) that grows in Wallacean. This species can be found only in the central part of the Moluccas, eastern Indonesia. Six populations (77 individuals in total) were sampled for S. javanica while three populations (27 individuals in total) were sampled for S. selanica. To determine genetic variation and population structure, three non-coding chloroplast DNA regions of trnL-trnF, psbC-trnS, trnS-trnfM and two non-coding chloroplast DNA regions of trnT-trnL, trnL-trnF were sequenced from S. javanica and S. selanica, respectively. There was no variation in the chloroplast DNA regions from S. javanica, except for one unique indel polymorphism. Nucleotide diversity within S. selanica populations ranged from 0 (Seram) to 0.00044 (Buru), with a pooled value of 0.00041. S. javanica was determined as having no population structure while high levels of genetic differentiation was found among populations of S. selanica (F(ST) = 0.702). Different pattern of population structure among the two species in this study suggested the need for distinct management and conservation strategies for each species. For S. javanica, connectivity within and among populations, including augmentation of population size across the species range, should be promoted. For S. selanica, an in situ conservation plan that defines core areas completely free from perturbation within each population is necessary.