| dc.description.abstract | Garcinia forbesii merupakan anggota famili Clusiaceae yang memiliki perawakan pohon malar hijau dan menghasilkan getah berwarna kuning dan buah berwarna merah dengan stigma persisten saat matang. G. forbesii terdistribusi di Brunei Darussalam, Malaysia, Singapura, dan Indonesia, khususnya di Sumatra dan Kalimantan. Spesies ini berpotensi sebagai tanaman obat, bahan kosmetik, maupun tanaman buah atau tanaman konsumsi. Namun, potensi yang dimiliki G. forbesii tidak sebanding dengan ketersediaan informasinya di alam. Garcinia forbesii diketahui banyak ditemukan di Borneo, seperti di Brunei Darussalam, Sabah, dan Sarawak, sedangkan di Kalimantan atau wilayah Indonesia masih sangat terbatas. Oleh karena itu, penelitian terkait ekologi dan populasi G. forbesii di Borneo perlu dilakukan. Penelitian ini bertujuan memprediksi kesesuaian habitat dan faktor lingkungan yang mendukung distribusi G. forbesii di Borneo serta menganalisis populasinya berdasarkan marka molekuler untuk mengetahui profil keragaman dan struktur genetika populasinya di Kalimantan, Indonesia.
Eksplorasi G. forbesii dilakukan dengan purposive sampling di Kalimantan Barat, Kalimantan Tengah, dan Kalimantan Selatan berdasarkan informasi dari masyarakat setempat. Sebanyak 49 titik koordinat didapatkan dari eksplorasi di Kalimantan, Indonesia, serta 40 titik koordinat dari data Global Biodiversity Information Facility (GBIF) dan Herbarium Bogoriense (BO). Data titik koordinat G. forbesii, 1.036 titik koordinat Garcinia, serta variabel lingkungan iklim, radiasi, dan tanah digunakan untuk konstruksi model prediksi kesesuaian habitat berdasarkan skenario baseline (1970-2000) dan dua skenario masa depan Shared Socioeconomic Pathway (SSP) in sustainability 2.6 W/m² (SSP126) sebagai skenario perubahan iklim emisi rendah dan fossil-fueled development 8.5 W/m² (SSP585) sebagai perubahan iklim emisi ekstrem, untuk periode 2021-2040, 2041-2060, 2061-2080, dan 2081-2100. Selain model prediksi, dilakukan pengukuran kondisi habitat di lokasi populasi G. forbesii di Kalimantan untuk analisis iklim mikro dan sifat fisikokimia tanah di setiap populasi. Analisis secara molekuler dilakukan pada 49 individu G. forbesii dari Kalimantan, Indonesia, menggunakan 12 marka molekuler Inter Simple Sequence Repeat (ISSR). Hasil amplifikasi dilakukan skoring data biner yang selanjutnya dianalisis keragaman dan diferensiasi genetik setiap primer, sampel, dan populasinya dengan GenAlEx 6.51b2. Analisis struktur populasi dilakukan berdasarkan metode Principal Coordinate Analysis (PcoA) dan komposisi genetik perangkat lunak STRUCTURE v2.3.2. Analisis hubungan kekerabatan dilakukan dengan metode Unweighted Pair Group Method with Arithmetic (UPGMA) berdasarkan koefisien Jaccard. Hubungan antara ekologi dan keragaman genetik dianalisis dengan Isolation by Distance (IBD) dan Isolation by Environment (IBE) dengan uji Mantel menggunakan perangkat lunak RStudio.
Model prediksi kesesuaian habitat G. forbesii di Borneo berdasarkan skenario iklim saat ini dan masa depan memiliki rentang nilai AUC 0,785–0,802 atau pada kategori moderat. Berdasarkan metrik OR10 dan MaxSS, model memiliki performa yang baik, yaitu pada rentang nilai 0,09-0,13 dan 0,473-0,607. Berdasarkan tujuh variabel lingkungan dengan persentase kontribusi tertinggi, kesesuaian habitat G. forbesii di Borneo dipengaruhi oleh isotermalitas (Bio3) (61,3%), fraksi lempung (soil clay) (12,5%), dan karbon organik tanah (soil carbon) (9%). Berdasarkan nilai permutasi, model didukung oleh Bio3 (57,8%), karbon organik tanah (11,8%), curah hujan kuartal terdingin (Bio19) (9,3%), dan curah hujan kuartal terpanas (Bio18) (7,7%). Kesesuaian habitat G. forbesii di Borneo terpusat di selatan, barat, dan utara dengan luas area sebesar 142.116,55 km². Pada skenario SSP126, tingkat kesesuaian habitat diprediksi akan mengalami peningkatan (neto) sebesar 11,96% pada periode 2021-2040 dan mencapai puncaknya pada periode 2041-2060 sebesar 53,6%. Luas area kesesuaian habitat pada skenario SSP585 diprediksi akan mengalami peningkatan (neto) hingga 15,87% pada periode 2041-2060, namun menurun drastis pada periode selanjutnya sebesar -57,26% dan -58,56%.
Analisis genetika populasi dari 44 individu G. forbesii di Kalimantan bagian selatan berdasarkan marka molekuler ISSR memiliki tingkat keragaman yang tinggi. Primer ISSR dengan tingkat polimorfisme tertinggi dan memiliki kemampuan untuk diferensiasi genetik antarpopulasi G. forbesii di Kalimantan yaitu UBC807, sedangkan primer dengan performa terendah yaitu UBC861. Berdasarkan analisis keragaman genetik dengan parameter jumlah alel teramati (Na), jumlah alel efektif (Ne), indeks Shannon (I), dan heterozigositas harapan (He) pada setiap populasi di Kalimantan, populasi dari Bentok Darat (Kalimantan Selatan) memiliki tingkat keragaman paling rendah sedangkan populasi dengan tingkat keragaman tertinggi dari Sungai Asam (Kalimantan Selatan). Namun, berdasarkan diferensiasi genetik antarpopulasi, marka ISSR mendeteksi diferensiasi yang rendah, yaitu sebesar 0,159. Berdasarkan jarak genetik PhiPT dan Nei, nilai jarak genetik berbanding lurus dengan jarak geografis antarpopulasi. Sejalan dengan kondisi tersebut, G. forbesii di Kalimantan memiliki hubungan kekerabatan dan struktur populasi antarpopulasi yang tumpah tindih, namun populasi yang berasal dari Benangin (Kalimantan Tengah) dan Bongkang (Kalimantan Selatan) terpisah dengan populasi Bentok Darat, Biih, Pulau Nyiur, dan Sungai Asam dari Kalimantan Selatan. Kondisi keragaman genetik tersebut didukung oleh hasil analisis IBD dan IBE. Hasil IBD menunjukkan korelasi jarak geografis dengan disimilaritas Jaccard sebesar 0,3239. Hasil IBE menunjukkan nilai korelasi sebesar 0,2685 pada variabel lingkungan mikro dan 0,3363 pada variabel lingkungan makro. Hasil uji korelasi tersebut menunjukkan bahwa ekologi spasial berpengaruh terhadap kondisi genetika populasi yang memisahkan antarpopulasi G. forbesii di Kalimantan bagian selatan. | |
| dc.description.abstract | Garcinia forbesii is a member of the Clusiaceae family that has an evergreen tree stature and produces yellow sap and red fruits with persistent stigma when ripe. Garcinia forbesii is distributed in Brunei Darussalam, Malaysia, Singapore, and Indonesia, especially in Sumatra and Kalimantan. This species has the potential to be a medicinal plant, cosmetic ingredient, as well as fruit plants or consumption plants. However, the potential of G. forbesii is not comparable to the availability of information in nature. Garcinia forbesii is known to be widely found in Borneo, such as in Brunei Darussalam, Sabah, and Sarawak, while in Kalimantan or Indonesian territory it is still very limited. Therefore, research related to the ecology and population of G. forbesii in Borneo needs to be conducted. This study aims to predict the suitability of habitats and environmental factors that support the distribution of G. forbesii in Borneo and analyze its population based on molecular markers to determine the diversity profile and genetic structure of the population in Kalimantan, Indonesia.
Exploration of G. forbesii was carried out by purposive sampling in West Kalimantan, Central Kalimantan, and South Kalimantan based on information from the local community. A total of 49 coordinate points were obtained from exploration in Kalimantan, Indonesia, as well as 40 coordinate points from data from the Global Biodiversity Information Facility (GBIF) and the Bogoriense Herbarium (BO). Garcinia forbesii occurrence records, 1036 Garcinia occurrence records, as well as climatic, radiation, and soil environmental variables were used for the construction of habitat suitability prediction models based on baseline scenarios (1970-2000) and two future scenarios Shared Socioeconomic Pathway (SSP) in sustainability 2.6 W/m² (SSP126) as low-emission climate change scenarios and fossil-fueled development of 8.5 W/m² (SSP585) as climate change extreme emissions, for the periods 2021-2040, 2041-2060, 2061-2080, and 2081-2100. In addition to the prediction model, habitat conditions were measured at the location of the G. forbesii population in Kalimantan for the analysis of the microclimate and physicochemical properties of the soil in each population.
Molecular analysis was carried out on 44 samples of G. forbesii from Kalimantan, Indonesia using 12 molecular markers of Inter Simple Sequence Repeat (ISSR). The results of amplification were carried out by scoring binary data which was then analyzed for diversity and genetic differentiation of each primary, sample, and population with GenAlEx 6.51b2. Population structure analysis was performed based on the Principal Coordinate Analysis (PCoA) method and genetic composition of the STRUCTURE v2.3.2 software. The analysis of kinship relationships was carried out using the Unweighted Pair Group Method with Arithmetic (UPGMA) method based on Jaccard coefficient. The relationship between ecology and genetic diversity was analyzed with Isolation by Distance (IBD) and Isolation by Environment (IBE) with the Mantel test using RStudio software.
The prediction model of habitat suitability of G. forbesii in Borneo based on current and future climate scenarios has an AUC value range of 0.785–0.802 or in the moderate category. Based on OR10 and MaxSS metrics, the model performs well, namely in the value range of 0.09-0.13 and 0.473-0.607. Based on the seven environmental variables with the highest percentage of contribution, the habitat suitability of G. forbesii in Borneo is influenced by isothermality (Bio3) (61.3%), soil clay content (12.5%), and soil organic carbon (9%). Based on permutation impotances, the model is supported by Bio3 (57.8%), soil organic carbon (11.8%), coldest quarter rainfall (Bio19) (9.3%), and hottest quarter rainfall (Bio18) (7.7%). The habitat suitability of G. forbesii in Borneo is concentrated in the south, west, and north with an area of 142,116.55 km². In the SSP126 scenario, the level of habitat suitability is predicted to increase (net) by 11.96% in the 2021-2040 period and reach its peak in the 2041-2060 period of 53.6%. The area of habitat suitability in the SSP585 scenario is predicted to increase (net) to 15.87% in the 2041-2060 period, but decrease drastically in the next period by -57.26% and -58.56%.
Population genetic analysis of 44 individuals of G. forbesii in southern Borneo based on the molecular markers of ISSR has a high level of diversity. The ISSR primary with the highest level of polymorphism and the ability to genetically differentiate between populations of G. forbesii in Kalimantan is UBC807, while the primary with the lowest performance is UBC861. Based on the analysis of genetic diversity with parameters the number of observed alleles (Na), the number of effective alleles (Ne), the Shannon index (I), and the expected heterozygosity (He) in each population in Kalimantan, the population from Bentok Darat (South Kalimantan) has the lowest level of diversity while the population with the highest level of diversity is from Sungai Asam (South Kalimantan). However, based on genetic differentiation between populations, the ISSR score detected a low differentiation, which was 0.159. Based on the genetic distance of PhiPT and Nei, the value of genetic distance is directly proportional to the geographic distance between populations. In line with these conditions, G. forbesii in Kalimantan has a kinship relationship and population structure between overlapping populations, but populations originating from Benangin (Central Kalimantan) and Bongkang (South Kalimantan) are separate from the populations of Bentok Darat, Biih, Nyiur Island, and Sungai Asam from South Kalimantan. The genetic diversity condition is supported by the results of IBD and IBE analysis. The results of IBD showed a correlation of geographic distance with Jaccard disimilarity of 0.3239. The results of IBE showed a correlation value of 0.2685 for the micro environment variable and 0.3363 for the macro environmental variable. The results of the correlation test showed that spatial ecology had an effect on the genetic conditions of the population that separated the populations of G. forbesii in southern Kalimantan. | |
