A study of genetic variation of eel-loach, Pangio spp. (family : Cobitidae) using PCR-RAPD and partial mtDNA sequencing methods

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Date
2002-09
Authors
Ali @ Jaafar, Ruzainah
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Abstract
A total of 98 individuals of seven species of Pangio, were collected from various localities for genetic investigation; P. oblonga - Sungai Padang Sanai, Kedah (Northern Peninsular Malaysia), P. muraeniformis - Sungai Terlang, Pahang (Central Peninsular Malaysia), P. kuhlii - Sungai Terlang, Pahang. P. piperata - Sungai Sekayu and Sungai Kemat (both are located in Terengganu, North East of Peninsular Malaysia). RAPD technique and partial mtDNA 16S rR..!"iA gene sequencing were applied in this study to investigate the intra and interspecies genetic variation as well as the taxonomic status of a few member species. Nine RAPD primers (OPA-03, OPA-09, OPA-18, OPAB-02, OPAB-04, OPAB-05, OPAB-06, OPAB-07 and OPAB-09) were chosen based on their abilities to produce well-defined and reproducible banding patterns. The RAPD fragments observed showed a high degree of polymorphism within species. The percentages of polymorphism ranged ITom 45.21 ± 24.5 to 80.08 ± 13.5 while the average value of intrapopulation genetic distance range from 0.1038 ± 0.22 to 0.2540 ± 0.11. Individuals within population are closely related having an average genetic distance of 0.2 or less. Interspecific genetic distances ranged from 0.3414 - 0.7984. The genetic distances between the two P. piperata and P. shelfoldii populations were also higher than 0.2, i.e. 0.41 and 0.35 respectively. The genetic distances between P. shelfoldii - P. muraeniformis (0.3414) and P. kuhlii - P. semicincta (0.3793) also fen within the range of interpopulation rather than obvious interspecies distances. The Unweighted Pair-Group Method with Arithmetic Averaging (UPGMA) dendrogram constructed showed the close relationship between P. shelfoldii and P. muraeniformis and between' P. kuhlii and P. semicincta. Thus, based on the results of the studies done using the RAPD technique, the taxonomic status of P. muraeniformis and P. semicincta is sti II ambiguous. Variation in the partial 16S ribosomal gene sequence of the mitochondrial DNA was detennined to investigate the intra and interspecies genetic characteristics. The range for the homologous percentages or similarity percentages intra and interspecies was between 83.S - 99.8% with an average of 90.6 ± 3.8. The range of genetic distance values estimated from the 16S rRNA gene sequences was 0.017 - 0.1662 (with an average of 0.0889 ± 0.038). The lowest interspecies genetic distance (0.017) was between the two presumed species - P. kuhlii and P. semincincla. This result strongly suggests that the individuals identified as P. semicincla and P. kuhlil belong to the same species. The genetic distance data for intraspecies (also interpopulation) analysis which are represented by two species of Pangio - P. piperata (collected from Sungai Kemat and Sungai Sekayu) and P. shelfoldii (collected from Sungai Batang Pinang and Sungai Jelutong) were 0.11 and 0.0142 respectively. The intrapopulation genetic distance was only represented by individuals of P. oblonga and as expected _ this produced the lowest value of 0.012, which is lower than the interpopulation and intraspecies genetic distance values. In general, both techniques have proven to be successful for inyestigating the genetic variation of the Pangio complex.
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Investigate the intra and interspecies genetic variation as well as , the taxonomic status of a few member species.
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