Revised Phylogeny of Extant Xiphosurans (Horseshoe Crabs)
An attempt was made to revise the molecular phylogeny of extant xiphosurans (Horseshoe crabs) using universal barcode gene cytochrome oxidase C subunit 1. All four extant horseshoe crab species namely Limulus polyphemus (American horseshoe crab), Tachyple
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Abstract An attempt was made to revise the molecular phylogeny of extant xiphosurans (Horseshoe crabs) using universal barcode gene cytochrome oxidase C subunit 1. All four extant horseshoe crab species namely Limulus polyphemus (American horseshoe crab), Tachypleus gigas, T. tridentatus and Carcinoscorpius rotundicauda (Asian conspecifics) together with predicted ancestral lineages (insects, scorpions and common crabs) were considered for phylogram construction using distance matrix methods. Genetic distance (GD) data analysis revealed the distant genetic relatedness of L. polyphemus with Asian conspecifics. More interestingly, the monophyletic origin of Tachypleus gigas and Tachypleus tridentatus was quite evident in the phylogram which other molecular markers failed to address. Close genetic relatedness of horseshoe crabs with insects showed that they might have evolved from ancient aquatic insects. The efficiency of cytochrome oxydase C subunit 1 gene in species level identification among the horseshoe crab genome was clear in both the phylogram together with the precise identification of the differential developmental stages to the species level. Keywords Horseshoe crabs Malaysia
Living fossil
Xiphosuran
Genetic lineage
B. Akbar John (&) K. Zaleha INOCEM Research Station (IRS), Kulliyyah of Science, International Islamic University Malaysia, Kuantan, Pahang, Malaysia e-mail: [email protected] H.I. Sheikh Department of Biotechnology, Kulliyyah of Science, International Islamic University Malaysia, Kuantan, Malaysia K.C.A. Jalal B.Y. Kamaruzzaman Department of Marine Science, Kulliyyah of Science, International Islamic University Malaysia, Kuantan, Malaysia © Springer International Publishing Switzerland 2016 S. Trivedi et al. (eds.), DNA Barcoding in Marine Perspectives, DOI 10.1007/978-3-319-41840-7_7
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1 Introduction Among the bewildering array of animal taxa, horseshoe crabs are unique in their genetic makeup and are commonly known as “Living Fossil”. An Intriguing characteristic of horseshoe crabs is that they are morphologically similar in look and having virtually unchanged genetic makeup which helped them in withstanding various environmental stresses for the past 150 million years (Rudkin and Young 2009; Kamaruzzaman et al. 2011). It is interesting to note that, within the impressive diversity and ecological range of extant chelicerate arthropods, only the xiphosurid horseshoe crabs retain a primitively obligate aquatic habit harking back to their distant genealogical roots. It was noted that the fossil record of the basic xiphosurid horseshoe crab body plan has been extended back to the late Ordovician Period, about 445 million years ago, demonstrating an origin that lies outside of the paraphyletic ‘synziphosurines’ (Obst et al. 2012). Global distribution pattern of four extant species of horseshoe crabs showed restricted inhabitation of Limulus polyphemus along the American coastline especially in Gulf of Mexico, while other three Asian conspecifics s
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