The population structure of Haptosquilla glyptocerus in the Philippines as inferred by mitochondrial DNA oxidase 1

In identifying patterns in the genetic distribution of the species, possible mechanisms which drive high diversity in the Coral triangle are reflected. This study makes use of the species Haptosquilla glyptocercus and a 624 bp portion of its mitochondrial DNA gene, cytochrome oxidase 1 to examine its population structure. H. glyptocercus is one of the most widely distributed and abundant species of stomatopods with a moderately pelagic larval stage which would contribute to higher possibility of gene exchange between different localities. Added to that, this species has a wider range of possible habitat, from shallow reefs flats 0-2m from shore, sea grass beds to reefs greater than 10 km from shore. These two factors suggests that the species is capable of widespread dispersion. Of the 131 successfully sequenced samples, 91 haplotypes were identified. Of the 91 haplotypes, 51 are singletons occurring in one individual in a location. The traditional assessment of the population genetic structure of Haptosquilla glyptocercus indicates that this species exhibits a general lack of structure for the Philippines (ΦST=0.00894, pvalue = 0.01). The low ΦST is a stark contrast with what was previously reported for this species which was as high as ΦST=0.55, indicating a strong population structure. This is further supported by the absence of genetic breaks in the minimum spanning tree constructed that was previously identified for this species in Indonesia. The high haplotype diversity and low nucleotide diversity would indicate that the population has recently undergone a population expansion. The population structure of this species for the Philippines is better understood when it is compared with the adjacent regions. Adding the data previously obtained in Indonesia, the high ΦST (ΦST= 0.79874, p-value= 0.0) is obtained. However, examining this result more closely and removing certain population when computing for ΦST, it is seen that when the Philippines is examined with central Indonesia alone, the ΦST value lowers to 0.08224, p-value = 0.0, indicating a lack of structure. This indicates that the Philippines and central Indonesia are one population. The pattern of the genetic distribution is more consistent with present day oceanographic conditions rather than the Pleistocene events. This is evident in the lack of structure in the Philippines wherein the glaciation and deglaciation event should have caused structure in the organism. The general lack of structure in the Philippines and the exchange occurring between it and Indonesia is more consistent with the reversing monsoonal systems in the Region. Alternative explanations to the lack of structure influenced by the Pleistocene in the region are the possibility that gene flow was quickly re-established after the glacial events. Another factor to consider is the biological and ecological needs of the organism, it being more adaptable to diverse environments and its moderately long pelagic phase. The high ΦST values merit the examination of the possibility of the existence of cryptic species