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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Keywords
Investigate the intra and interspecies genetic variation as well as , the taxonomic status of a few member species.