Morphology and Phylogeography of Clavularia inflata Schenk, 1896 Schenk, 1896 (Soft Coral: Stolonifera) in Indonesian Coastal Waters.
Date
2021Author
Subhan, Beginer
Bengen, Dietriech
Madduppa, Hawis
Ferse, Sebastian
Metadata
Show full item recordAbstract
The Coral Triangle is recognized as the center of the world’s marine biodiversity, with species richness declining gradually from this region to the east across the Pacific Ocean and west across Indian Ocean. This region covers many countries, such as Indonesia, Malaysia, Philippines, Brunei, East Timor (Timor Leste), Papua New Guinea, and Solomon Islands.
There are around 96 genera and 23 families of soft coral in the Indo-Pacific. In Indonesia around 219 species, 28 genera, and 4 families of soft corals have been recorded. Clavularia is spread widely throughout the Indian and Pacific Ocean, stretching from the Red Sea and East Africa across the Indo-Pacific, reaching as far east as Micronesia. Clavularia is stoloniforous zooxanthellae soft coral, each one of the polyps is connected to the base. Polyps are pink to brownish gray and about 30 mm in diameter. Stolons are brown to dark red, and are often covered with algae or sponges.
Genetic connectivity is the key of conservation because it plays important roles in maintaining populations and the potential for restoring damage to the marine environment. The connectivity patterns of sessile animals are affected by reproduction and larval spread. The stage of pelagic larvae is the initial stage of life for recruitment, so that it can maintain its population from extinction. Besides, the pattern of genetic connectivity can help in designing management plans for marine protected areas, which in turn can help to preserve biodiversity. Genetic connectivity between coral reefs is often overlooked when designing an area, but it is very important to ensure the continuity of populations or protection of biodiversity.
This study aimed to confirm the identity of 25 colonies collected from 13 Indonesian coral reef location putatively identified as Clavularia inflata using molecular tools, and to describe them morphologically to verify defining characteristics and describe their morphological plasticity. Specimens were morphologically described based on their sclerite characteristics and compared between sites. All specimens were confirmed as Clavularia inflata by molecular identification using mitochondrial DNA with the mtMuts gene. Sclerite observations were divided into four parts for each colony, namely pinnules (finger-like extensions along the tentacless sides), crowns (tentacles covering the upper side of polyps, located between tentacles and calyx), calyx (the middle part of polyps), and stolons (branching between polyps). The form of sclerites found in Clavularia inflata comprised various forms such as rods, fingers, sticks, and brackets. The shortest size sclerites were found in the pinnule. These sclerites had a variety of sclerites such as grains with various geometric shapes such as platelet or finger biscuit shape. In the crown, the form of sclerites found was spindle-shaped sclerites (oval shaped with a shaft in the middle) with a curved shape. The middle part of the polyp (the calyx) is mostly covered by rod-shaped sclerites. Morphometric measurements of Clavularia inflata showed specimens from Kepulauan Seribu, Jakarta had the largest pinnule, calyx, and stolon compared to other locations. The maximum mean length of pinnule, calyx, and stolon were 145.1±19.27 µm, 1605.6±30.58 µm, and 749.5±52.8 µm, respectively. The maximum mean length of crown was 672,6±39.58 µm, found in Maluku Tenggara Barat. The phylogenetic tree of the soft coral Clavularia inflata, built using the Neighbor-Joining (NJ) method with the Kimura 2-parameter model, and a bootstrap value of 1000x, shows two large clades of the sample used to indicate the compatibility of the nucleotide base chain with the data from Gen bank. Hence, all samples belong to one (the same) species. Information from Automatic Barcode Gap Discovery (ABGD) shows that there are two major groups of Clavilaria inflata found in Indonesia. Together with the morphological data, this suggests the presence of cryptic species in this taxon.
This research aimed to determine the intraspecific genetic diversity and connectivity based on partial sequences of the mitochondrial mtMUTs gene of the of Clavularia inflata population from multiple coral reef communities in Indonesia. Population samples were obtained from eight coral reef locations namely Natuna Sea, Tanjung Lesung, Seribu Islands, Bontang, Lombok, Kangean, Sulawesi Sea, and Banda Sea. A total of individuals was collected and amplified using mtMUTs of mitochondrial DNA. Furthermore, genetic diversity was analysed based on the parameters of haplotype diversity (Hd) and nucleotide diversity (π), while genetic structure and connectivity were analysed by AMOVA and network analyses, respectively. The results showed that the lowest haplotype diversity (Hd) value was found at Natuna Sea and Kangean, and the highest at Bontang. The haplotype diversity ranged between 0 and 0.7421, while nucleotide diversity ranged between 0 and 0.2613. Therefore, the lowest values of π were observed at Natuna and Kangean, and the highest at Bontang. The genetic diversity of Clavularia inflata varied significantly between eight location and signified the presence of genetic connectivity between populations at eight sampling locations across the Indonesian region. However, no significant genetic structure was observed throughout the study region. The results obtained serve as an important baseline for further assessments which include additional populations from adjacent regions. Coral Triangle diakui sebagai pusat keanekaragaman hayati laut dunia, dengan kekayaan spesies menurun secara bertahap dari wilayah ini ke timur melintasi Samudra Pasifik dan barat melintasi Samudra Hindia. Wilayah ini mencakup banyak wilayah, seperti Indonesia, Malaysia, Filipina, Brunei, Timor Leste (Timor Leste), Papua Nugini, dan Kepulauan Solomon.
Terdapat sekitar 96 marga dan 23 famili karang lunak di Indo-Pasifik. Terumbu karang lunak di Indonesia tercatat sekitar 219 spesies, 28 marga, dan 4 famili. Clavularia tersebar luas di seluruh Samudra Hindia dan Pasifik, membentang dari Laut Merah dan Afrika Timur melintasi Indo-Pasifik, mencapai sejauh timur Mikronesia. Clavularia yang dikenal dengan stolonifera merupakan karang lunak dari genus zooxanthellae, yang masing-masing polipnya terhubung ke dasar. Polip bisa berwarna merah muda sampai abu-abu kecoklatan dan berdiameter sekitar 30 mm. Stolon berwarna coklat sampai merah tua, dan sering kali ditutupi dengan alga atau spons.
Konektivitas genetik merupakan kunci konservasi karena berperan penting dalam memelihara populasi dan memulihkan kerusakan lingkungan laut. Pola hubungan hewan sesil dipengaruhi oleh reproduksi dan penyebaran larva. Tahap larva pelagis merupakan tahap awal kehidupan regenerasi, sehingga dapat menjaga populasinya dari kepunahan. Selain itu, pola konektivitas genetik dapat membantu pengelolaan kawasan konservasi perairan. selanjutnya, pada gilirannya akan melestarikan keanekaragaman hayati. Keterhubungan genetik antar terumbu karang seringkali terabaikan saat merancang suatu kawasan, namun sangat penting untuk menjamin kelangsungan populasi atau perlindungan keanekaragaman hayati.
Penelitian ini bertujuan untuk mengkonfirmasi identitas 25 koloni yang dikumpulkan dari 13 lokasi terumbu karang Indonesia Clavularia inflata dengan menggunakan alat molekuler, dan mendeskripsikannya secara morfologis untuk memverifikasi karakteristik pendefinisian dan mendeskripsikan plastisitas morfologisnya. Spesimen dideskripsikan secara morfologis berdasarkan karakteristik skleritnya dan dibandingkan antar lokasi. Semua spesimen dikonfirmasi sebagai Clavularia inflata dengan identifikasi molekuler menggunakan DNA mitokondria dengan gen mtMuts. Pengamatan sklerit dibagi menjadi empat bagian untuk setiap koloni, yaitu pinnule (ekstensi seperti jari di sepanjang sisi tentakel), crown mahkota (tentakel menutupi sisi atas polip, terletak di antara tentakel dan kelopak), calyx (bagian tengah polip), dan stolon (percabangan di antara polip). Bentuk sklerit yang terdapat pada Clavularia inflata terdiri dari berbagai macam bentuk seperti batang, jari, stik, dan keranjang. Sklerit ukuran terpendek ditemukan di pinnule. Sklerit ini memiliki variasi sklerit berupa butiran dengan berbagai bentuk geometris seperti bentuk platelet atau biskuit jari. Pada crown, bentuk sklerit yang ditemukan adalah sklerit berbentuk gelendong (berbentuk lonjong dengan tangkai di tengah) dengan bentuk melengkung. Bagian tengah polip (calyx) sebagian besar tertutup oleh jenis sklerit berbentuk batang. Hasil pengukuran morfometri Clavularia inflata menunjukkan spesimen dari Pramuka memiliki pinnule, calyx, dan stolon terbesar dibandingkan lokasi lain. Panjang rata-rata maksimum pinnule, calyx, dan stolon masing-masing adalah 145,1 ± 19,27 µm, 1605,6 ± 30,58 µm, dan 749,5 ± 52,8 µm. Rata-rata panjang maksimal 672,6 ± 39,58 µm terdapat di Maluku Tenggara Barat. Pohon filogenetik karang lunak Clavularia inflata menggunakan metode Neighbor-Joining (NJ) dengan model Kimura 2-parameter, nilai bootstrap 1000x, menunjukkan dua klade besar sampel yang digunakan untuk menunjukkan kesesuaian rantai dasar nukleotida dengan data dari Genbank. Dengan demikian dapat dikatakan bahwa sampel berada dalam satu spesies. Informasi dari Automatic Barcode Gap Discovery (ABGD) menunjukkan bahwa ada dua kelompok besar Clavilaria inflata yang ditemukan di Indonesia. Bersama dengan data morfologi, hal ini menunjukkan adanya spesies kriptik.
Penelitian ini bertujuan untuk mengetahui keragaman dan konektivitas genetik intraspesifik berdasarkan sekuens parsial gen mtMUTs mitokondria populasi Clavularia inflata dari berbagai komunitas terumbu karang di Indonesia. Sampel populasi diperoleh dari delapan lokasi terumbu karang tersebut yaitu Laut Natuna, Tanjung Lesung, Kepulauan Seribu, Bontang, Lombok, Kangean, Laut Sulawesi, dan Laut Banda. Total individu dikumpulkan dan diamplifikasi menggunakan DNA mitokondria mtMUTs. Selanjutnya keragaman genetik dianalisis berdasarkan parameter keanekaragaman haplotipe (Hd) dan keanekaragaman nukleotida (π), sedangkan struktur genetik dan konektivitas masing-masing dianalisis dengan AMOVA dan analisis jaringan. Hasil penelitian menunjukkan bahwa nilai keanekaragaman haplotipe (Hd) terendah terdapat di Laut Natuna dan Kangean, dan tertinggi di Bontang. Keragaman haplotipe berkisar antara 0 dan 0,7421, sedangkan keanekaragaman nukleotida berkisar antara 0 dan 0,2613. Oleh karena itu, nilai π terendah diamati di Natuna dan Kangean, dan tertinggi di Bontang. Keragaman genetik Clavularia inflata sangat bervariasi antara delapan lokalitas dan menandakan adanya keterhubungan genetik antar populasi pada delapan lokalitas sampling di seluruh wilayah Indonesia. Namun, tidak ada struktur genetik yang signifikan yang diamati di seluruh wilayah studi. Hasil yang diperoleh berfungsi sebagai dasar penting untuk penilaian lebih lanjut yang mencakup populasi tambahan dari wilayah yang berdekatan.
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