Population, morphological, and genetic characteristics of pelawan trees on Bangka Island, Indonesia: implications for conservation

Abstract

Tristaniopsis spp. (pelawan) trees hold great significance in ensuring biodiversity sustainability and supporting the local species within Kepulauan Bangka Belitung Province. Moreover, it plays a crucial role in fostering the social and cultural aspects of the local community. However, the pelawan population has faced great threats due to land conversion, unmanaged forests, and mining. To address these challenges, the local government has shown a commitment to expanding the in-situ conservation areas beyond Namang Biodiversity Park. In order to enhance the conservation status of this species, it is essential to conduct a comprehensive study of the tree’s distribution, morphological characteristics, species delimitation, and genetic diversity. Therefore, this study aimed to obtain information on pelawan distribution, morphological characteristics, species confirmation, and genetic diversity. It was conducted at five natural populations, namely KK (Kota Kapur), BB (Berbura), LAP (Labuh Air Pandan), PN (Pangkal Niur), and LB (Limbung), and the genetic character was observed using ITS and RAPD markers. The first instance of establishing a nucleotide sequence database for pelawan on Bangka Island was also represented, showing the presence of two distinct taxa groups based on ITS sequence nucleotides. Based on morphological characters (bark color and leaves), the two groups were determined to be pelawan merah/orange (Tristaniopsis sp. 1) and pelawan air (Tristaniopsis sp. 2). Significantly, the genetic diversity analysis yielded a range of H_E values, from 0.283 (KK) to 0.353 (PN). The PCoA and dendrogram analyses exhibited the formation of a cluster comprising populations from Bangka (KK, BB, LAP, and PN), while LB formed a separate cluster. The result showed significant genetic differentiation between regions and populations, without mixing seeds or seedlings. It was suggested that the conservation strategy for pelawan trees on Bangka Island should be developed with several considerations. In-situ conservation sites should be designated based on the presence of pelawan merah/orange and pelawan air taxa. Additionally, ex-situ conservation plots needed to be established, with at least one location dedicated to each taxonomic group. To preserve the remaining natural genetic resources, KK and LB populations, which had the lowest H_E value and different genetic structures should be prioritized. Strategies for ex-situ conservation included KK, LB, and PN. The prioritization of PN for conservation was necessary, and further genetic study of the pelawan should involve larger populations representing the natural distribution of each species.

Keywords:

• Pelawan
• distribution
• specimen
• ITS
• RAPD

Acknowledgments

The authors are grateful to the Forestry Agency of Bangka Belitung Province for fully supporting the genetic materials.

Institutional Review Board statement

Not applicable.

Informed consent statement

Not applicable.

Author contributions

Y.W., A.Y.P.B.C.W., I.L.G.N., I.P., L.H., Y.H., A.I. P., A.S., T.H., S., Y., and M.H.S.: contributed in conceptualization, methodology, software, validation, formal analysis, investigation, resources, data curation, writing—original draft preparation, writing—review and editing, visualization, supervision, and project administration. All authors had an equal role as main contributors in discussing the conceptual ideas and the outline, providing critical feedback for each section, and writing the manuscript. All authors also have read and agreed to the published version of the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Data availability statement

Not applicable.

Additional information

Funding

Part of this study was funded by the Local Government of Bangka Belitung.