Abstract
An attempt was made to examine the influence of Malaysian continental drift on the genetic and haplotype diversity of Malaysian horseshoe crab (Tachypleus gigas [Muller, 1785]) distributed along the east coast of Peninsular Malaysia and distant Borneo Island. Mitochondrial DNA (AT rich region = 369bp) analysis showed that T. gigas has higher haplotype diversity in peninsular Malaysia compared to east Malaysian (Sarawak) samples. Highest haplotype diversity (h±SD) was observed among the Terengganu samples (0.813 ± 0.071) followed by Pahang samples (0.813 ± 0.065). There were no difference in nucleotide diversity (Pi) noted in east cost of Peninsular Malaysian (PM) samples. Overall haplotype (h±SD) and nucleotide (Pi±SD) diversity of T. gigas in PM samples including Sarawak was 0.827 ± 0.051 and 0.0078 ± 0.0014 respectively. A total of 6 unique haplotypes were recorded of which 2, 2 and 1 were unique to Terengganu, Sarawak and Pahang samples respectively. Pair wise haplotype frequency (FST) value was not statistically significant (P > 0.05) for all the groups indicating the limited gene flow among the population. In addition phylogenetic scrutiny visibly clustered T. gigas samples from T. tridentatus samples representing sound phylogenetic signals in mtDNA AT rich region. The findings from this study have important implications for proper management and conservation of horseshoe crab in Malaysia.
Highlights
Horseshoe crabs are a unique group of animals remarkably retaining their genetic makeup virtually unaffected over millions of years (Kamaruzzaman et al, 2011; John et al, 2010a)
We identified 14 haplotypes among the T.gigas samples from East coast of peninsular Malaysia (PM) including Sarawak
Haplotype diversity was comparatively higher in Peninsular Malaysian (PM) samples than east Malaysian T. gigas
Summary
Horseshoe crabs are a unique group of animals remarkably retaining their genetic makeup virtually unaffected over millions of years (Kamaruzzaman et al, 2011; John et al, 2010a). They are marine chelicerate arthropod belong to the class merostomata. Despite their name, they are more closely related to spiders, ticks and scorpions than to crabs (kamaruzzaman et al, 2011). There are four extant species of horseshoe crabs, Tachypleus tridentatus, Tachypleus gigas, Carcinoscorpius rotundicauda and Limulus polyphemus. Out of ISSN 1916-9671 E-ISSN 1916-968X four extant species of horseshoe crabs, 3 are inhabiting Malaysian coastal waters while the distribution of T. tridentatus is restricted to East Malaysian coasts (Sabah and Sarawak regions) (John et al, 2010)
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