Sai Kerisha Kntayya (2015) Characterisation of the genetic diversity within and among populations of the Asian horseshoe crab in Sabah using cytochrome oxidase 1 and microsatellite markers. Masters thesis, Universiti Malaysia Sabah.
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Abstract
Today, only four Horseshoe Crab species exists which includes Tachypleus tridentatus, Tachypleus gigas, Carcinoscorpius rotundicauda (found in Malaysian waters) and Limulus polyohemus (found only in American waters). In recent years, a decline in the number of Horseshoe Crabs has occurred due to various phenomena’s including habitat degradation which has prompted studies on the genetic architecture and population structure of the Horseshoe crabs. Consequently, this study was carried out using cytochrome oxidase 1 (C01) gene and microsatellite markers to understand the genetic structure of Horseshoe Crabs in Sabah. A total of 86 Horseshoe Crab samples were collected from five districts in Sabah namely Bongawan (21), Kota Kinabalu (15), Kota Belud (26), Kudat (14) and Tuaran (10). Sequence analysis of the cytochorome oxidase 1 (C01) gene identified the existence of three species namely Tachypleus tridentatus, Tachypleus gigas, and Carcinoscorpius rotundicauda when tested for similarity using BLAST. Amplification of 10 microsatellite loci (Tt01, PLbp2-2-2, PLbp11-10-2, TTLR1A, TTLR1B2, PLbp11-9-2, HCMS069, TTLR151, TTLR152, and TTLR121) on T. gigas, C. rotundicauda and T. tridentatus was successfully carried out. All loci were observed to be polymorphic except for locus TTLR1A (Kudat) and locus TTLR151 (Tuaran). The number of alleles ranged from 2 to 6 per locus. The mean observed heterozygosities (Ho) and the mean expected heterozygosities (He) were between 0.55 and 0.72, and between 0.40 and 0.59, respectively indicating a satisfactory level of genetic diversity of the T.gigas population in Sabah. Hardy-Weinberg Equilibrium analysis showed deviation with the highest χ2 value in locus TTLR1A (93.003) and the lowest in locus TTLR151 (10.108). The dendrogram constructed based on Nei’s (1978) genetic distance using UPGMA method showed a distinct cluster of samples from all five locations with samples from Bongawan forming one cluster, samples from Kota Kinabalu and Tuaran forming the second cluster, and Kota Belud and Kudat forming the third cluster, indicating consistency with geographical locations of each population. This study shows moderately high levels of genetic diversity of the Horseshoe Crab population in Sabah. However, population density is constantly declining. This research provides molecular information that could be used to implement different conservation strategies for the Horseshoe Crab population in Sabah.
| Item Type: | Thesis (Masters) |
|---|---|
| Keyword: | Genetic, Horseshoe crab, Populations |
| Subjects: | Q Science > QH Natural history > QH301-705.5 Biology (General) > QH426-470 Genetics |
| Department: | INSTITUTE > Biotechnology Research Institute (BRI) |
| Depositing User: | DG MASNIAH AHMAD - |
| Date Deposited: | 07 Aug 2024 08:37 |
| Last Modified: | 07 Aug 2024 08:37 |
| URI: | https://eprints.ums.edu.my/id/eprint/39459 |
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