Phylogenetics Of Mud Crab Genus Scylla And Phylogeographical Distribution Of S. Olivacea (Brachyura: Portunidae) In Malaysia
Loading...
Date
2016-01
Authors
Mohamad Rosly, Hurul Adila-Aida
Journal Title
Journal ISSN
Volume Title
Publisher
Universiti Sains Malaysia
Abstract
This study was focused on the phylogenetics of the genus Scylla and
phylogeographical distribution of S. olivacea in Malaysia based on 542 base pairs
(bp) of the mitochondrial cytochrome c oxidase I (COI) gene. A total of 201
individuals were sampled from seven locations throughout peninsular Malaysia, and
a single population each from Sabah and Sarawak. The most abundant species was S.
olivacea (111 individuals), followed by S. tranquebarica (61 individuals) and S.
paramamosain (29 individuals). However, S. serrata specimens were not found
during sampling and therefore imported samples were obtained from restaurants for
inclusion in the analyses. Phylogenetic analyses were conducted using the neighbour
– joining (NJ) and maximum parsimony (MP) methods based on MEGA ver. 5.05.
Both statistical methods revealed the reciprocally monophyletic relationships among
S. olivacea, S. paramamosain, S. tranquebarica and S. serrata strongly supporting
the presence of three species of Scylla namely S. olivacea, S. paramamosain, S.
tranquebarica and the absence of S. serrata in Malaysian waters. Haplotype
sequences were obtained using Collapse ver. 1.2, revealing 66 haplotype sequences
of S. olivacea; where 14 of them were shared among populations while the remaining
sequences were unique. Analysis of molecular variance (AMOVA) was conducted
using ARLEQUIN ver. 3.11 software. Investigation of evolutionary history was
conducted based on Fu’s Fs and Tajima’s D tests. Phylogeographical distribution of
Scylla olivacea revealed a lack of geographical structuring in their haplotype
distribution. The highest haplotype diversity was observed in Kelantan (h = 1.000 ± 0.127 SD) whereas the highest nucleotide diversity was observed in Penang and
Sarawak with a value of π = 0.012 ± 0.006 SD. The Fu’s Fs and Tajima’s D tests
showed negative values, but non-significant for all populations (except for Penang,
Perlis, Perak and Sarawak populations, where the Fu’s Fs test were significant). The
mismatch distribution analysis was performed using DNASP ver. 5.10. This analysis
showed a multimodal pattern which indicates a reduced demographic growth with a
subsequent expansion. The non-significant FST and low genetic distance values,
supported by the phylogenetic trees (NJ and MP trees) were indicative of no
significant genetic differentiation between populations. A minimum spanning
network (MSN) was conducted to depict the haplotype changes and relationship
among haplotypes using Network ver. 4.6.1.3. The MSN revealed a complex
reticulate network with two dominant haplotypes interconnected mainly through
singletons. These results indicate a complex demographic history of S. olivacea
populations in Malaysia with a common history, and/or high gene flow via
hydrological factors but with a potential for independent evolution. The present study
could serve as a reference for further investigation on aquaculture and conservation
management.
Description
Keywords
Phylogenetics of mud crab