Genetic mixing between distribution areas of Birgus latro based on maternal lineage molecular markers

¹ Department of Biology, Faculty of Mathematics and Natural Science, IPB University, Bogor 16680, Indonesia
² Departement of Aquatic Resources Management, Faculty of Fisheries, IPB University, Bogor 16680, Indonesia

^* Corresponding author: achamad@apps.ipb.ac.id

Abstract

The distribution of Birgus latro, commonly known as the coconut crab, is influenced by its planktonic larvae, which migrate along ocean currents. The larvae’s planktonic phase, facilitates genetic exchange among B. latro subpopulations, particularly between geographically proximate islands. This study investigates the genetic mixing across B. latro distribution ranges in the Pacific and Indonesia. DNA was extracted from hemolymph voucher specimens collected between 2017 and 2018. A total of 32 samples from four subpopulations - Derawan Island (n = 9), Morotai Island (n = 2), Ternate (n = 11), Yoi Gebe Island (n = 10) - were analyzed. The mitochondrial CO1 gene was amplified via PCR and sequenced. These sequences were then aligned with publicly homologous data from various Pacific locations. The reconstruction of phylogeographic tree based on the NJ grouping did not find any grouping supported by bootstrap values >50%. Genetic diversity within subpopulations (0.0113) is much greater than between subpopulations (0.0017). From a total of 102 sequence data grouped into 49 haplotypes. There is no specific haplotype that correlates with a specific location. This strengthens the suggestion that the longer age of pelagic larvae will cause genetic mixing between subpopulations.