Understanding factors driving diversity across biodiversity hotspots is critical for formulating conservation priorities in the face of ongoing and escalating environmental deterioration. While biodiversity hotspots encompass a small fraction of Earth's land surface, more than half the world's plants and two-thirds of terrestrial vertebrate species are endemic to these hotspots. Tropical Southeast (SE) Asia displays extraordinary species richness, encompassing four biodiversity hotspots, though disentangling multiple potential drivers of species richness is confounded by the region's dynamic geological and climatic history. Here, we use multilocus molecular genetic data from dense multispecies sampling of freshwater fishes across three biodiversity hotspots, to test the effect of Quaternary climate change and resulting drainage rearrangements on aquatic faunal diversification. While Cenozoic geological processes have clearly shaped evolutionary history in SE Asian halfbeak fishes, we show that paleo-drainage re-arrangements resulting from Quaternary climate change played a significant role in the spatiotemporal evolution of lowland aquatic taxa, and provide priorities for conservation efforts.
Genetic polymorphism in kingfish, collected from coastal waters of Japan, Australia and New Zealand, were examined using microsatellite (MS) DNA and mitochondrial DNA (mtDNA) control region markers. Sixteen to 25.7 alleles per locus were observed in three MS markers, while the average observed (and expected) heterozygosities were 0.782 (0.918), 0.750 (0.809) and 0.650 (0.888) for Australian, Japanese and New Zealand kingfish, respectively. Twelve mtDNA haplotypes were detected by the digestion of control region sequences with five endonucleases: HaeIII, HinfI MboI, RsaI and TaqI. Significant genetic divergence was observed between the kingfish population from Japan and those from Australia–New Zealand. There was no significant differentiation among the Australian and New Zealand population samples.
PENDAHULUANIkan nila di Indonesia merupakan ikan ekonomis penting di dunia karena cara budidaya yang mudah, rasa yang digemari, harga relatif terjangkau, dan memiliki toleransi yang luas terhadap lingkungan. Dewasa ini, ikan nila dipelihara secara komersial berbagai belahan dunia baik di kolam atau keramba jaring apung (KJA) di air payau maupun air tawar serta perairan pantai. Disebabkan oleh minat masyarakat yang semakin meningkat, ikan nila ini menjadi komoditi yang menarik, baik dalam usaha budidaya skala besar maupun skala kecil. (Fish Farming Intl., 2005). Setengah dari impor Amerika Utara dipasok oleh China, sedangkan sisanya oleh Taiwan, Thailand, dan Indonesia. USDA (United State Department of Agriculture) memberikan dukungan agar ketiga negara pengekspor utama dapat mengambil alih porsi impor yang dikuasai oleh China. Hal ini merupakan peluang yang harus disikapi secara positif. Patut diperhitungkan bahwa budidaya ikan nila telah mulai menarik perhatian negara-negara Amerika Selatan yang dapat menjadi pesaing handal karena transportasi yang lebih murah. Oleh karena itu penting sekali diupayakan budidaya yang efisien.Upaya peningkatan produksi ikan nila terus dilakukan dengan berbagai cara seperti mendatangkan beberapa strain unggul baru dari luar, perbaikan teknologi perbenihan dan budidaya, serta perbaikan genetik. Perbaikan perbenihan dan budidaya dilakukan dengan menggunakan teknologi maju, seperti penggunaan corong penetasan untuk perbenihan dan resirkulasi pada budidaya sistem tertutup, serta rekayasa wadah budidaya yang semakin maju. Untuk upaya perbaikan genetik antara lain dilakukan dengan menghasilkan jenis nila "monosex", rekayasa genetik, dan seleksi secara konvensional untuk menghasilkan strain ikan nila dengan tampilan yang spesifik (Wardoyo, 2005;Gustiano, 2007 ABSTRAKDewasa ini ikan nila merupakan salah satu ikan ekonomis penting di dunia yang dikenal sebagai freshwater chicken. Di Indonesia ikan nila telah dibudidayakan secara luas. Namun demikian kesediaan benih unggul dengan pertumbuhan cepat yang menguntungkan usaha budidaya nila masih merupakan kendala utama. Berdasarkan latar belakang ini, perbaikan mutu genetik nila untuk meningkatkan produksi dan produktivitas di masa mendatang sangat dibutuhkan. Dalam makalah ini akan diuraikan status, upaya, hasil riset pemuliaan, dan selective breeding yang telah dan sedang dilakukan di Indonesia dalam rangka untuk meningkatkan produksi dan produktivitas ikan nila nasional. Hasil yang diperoleh dari kegiatan selective breeding ikan nila "Balitkanwar" melalui seleksi famili diperoleh jenis unggulan yang baik keragaannya dari berbagai aspek yang diuji. Keragaan ikan nila "Balitkanwar" secara mendetail akan disampaikan dalam makalah ini.
Four microsatellite loci were identified for Clarias macrocephalus and the forward and reverse primers for each locus were designed according to their unique flanking regions. One locus, Cma-1 *, was monomorphic, three loci, Cma-2*, Cma-3 * and Cma-4*, were polymorphic having 5, 14 and 30 al leles per locus respectively. The polymorphic microsatellite loci were studied in four natural populations of C. macrocephalus collected from different locations in Thailand. Mean number of alleles per locus were 8.0, 8.7, 6.0 and 10.0, respective to populations from Pattani, Pattalung, Chiangrai and Prachin buri. Mean heterozygosities were 0.744, 0.765, 0.718 and 0.810 respectively. Nei's genetic distance showed the closest relationship between Pattalung and Prachinburi (0.230) and the largest genetic dis tance between Pattalung and Chiangrai (0.535). However, the genetic distances obtained in this study were not accorded with geographic distance.
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