Samrah, Siti Farah Quraishia
(2018)
Molecular approach to the identification and phylogenetic relationship among actinopterygii using mitochondrial DNA 12S rRNA, 16S rRNA and cytochrome B genes in Peninsular Malaysia.
Masters thesis, Universiti Sains Malaysia.
Abstract
The morphological based method has been utilised to identify and classify fish
species. However, this method is lacking genetic information which makes it less
useful in phylogenetic studies. The present study utilises mtDNA markers namely 12S
rRNA, 16S rRNA and cytochrome b genes to characterize, identify the polymorphism
and genetic relationship among marine fish species. The genetic relationship among
the selected marine fish species was inferred through phylogenetic trees using
Neighbor-joining (NJ), Maximum parsimony (MP) and Maximum likelihood (ML)
methods. The result showed that 12S rRNA gene was more conserved than 16S rRNA
and cytb genes based on the polymorphisms reported. The finding also revealed that
Nemipterus nemurus exhibits the highest number of polymorphisms indicating that
this species might have experienced the most changed events and thus possessing the
most genetic deviation from the common shared ancestry. All the phylogenetic trees
that were constructed based on 12S rRNA, 16S rRNA and cytochrome b genes showed
a similar clustering with slight differences in their bootstrap values. Some species with
greatly morphological resemblance such as Liza macrolepis and Liza vaigiensis
however, showed a genetically distant relationship. Nevertheless, another
morphological resemblance species namely Pampus argenteus / Pampus chinensis and
Drepane longimana / Drepane punctata were consistently observed in all topologies
with high bootstrap support (97-100%). Having a distinctive morphological, the
Megalaspis cordyla and Caranx sexfasciatus occupied a highly similar nucleotide
sequences and showed a consistent clustering in all topologies. This study also
revealed that the combined genes provide a better resolution for all phylogenetic trees.
Overall, these findings showed that the molecular based method using mtDNA genes
were successfully applied to study the diverse Malaysia marine fish species in class
Actinopterygii.
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