Liolophura species discrimination with geographical distribution patterns and their divergence and expansion history on the northwestern Pacific coast

Abstract

The chiton Liolophura japonica (Lischke 1873) is distributed in intertidal areas of the northwestern Pacific. Using COI and 16S rRNA, we found three genetic lineages, suggesting separation into three different species. Population genetic analyses, the two distinct COI barcoding gaps albeit one barcoding gap in the 16S rRNA, and phylogenetic relationships with a congeneric species supported this finding. We described L. koreana, sp. nov. over ca. 33°24′ N (JJ), and L. sinensis, sp. nov. around ca. 27°02′–28°00′ N (ZJ). We confirmed that these can be morphologically distinguished by lateral and dorsal black spots on the tegmentum and the shape of spicules on the perinotum. We also discuss species divergence during the Plio-Pleistocene, demographic expansions following the last interglacial age in the Pleistocene, and augmentation of COI haplotype diversity during the Pleistocene. Our study sheds light on the potential for COI in examining marine invertebrate species discrimination and distribution in the northwestern Pacific.

Chromosome-level genome assembly of the common chiton,Liolophura japonica(Lischke, 1873)

“…Liolophura japonica (Polyplacophora, Chitonidae) (Lischke 1873) (Figure 1A) is one of the most abundant polyplacophorans found on intertidal rocky reefs of the Asian continent including China, Korea, and Japan. This species diverged from the last common ancestor of Liolophura at ∼184 million years ago during the early Pleistocene period (Choi et al 2021). On the shore, they are distributed over a wide vertical range from the mid littoral zone to the low subtidal zone, where the animals experience periodic fluctuations in environmental conditions with the ebb and flow of the tide (Harper 1996; Harper & Williams 2001).…”

Possible species discrimination of a blotched nerite Nerita albicilla with their distribution pattern and demographic history in the Indo-Pacific

“…The evolutionary rate of mitochondrial DNA is faster than that of nuclear DNA, enough to examine genetic diversity and differentiation of not only closely related sibling species but also phylogeographically diverged genetic groups within a single species 8 – 12 . These characteristics make mitochondrial DNA particularly appropriate for tracing recent evolutionary history, including colonization or translocation events and population bottlenecks 13 .…”

“…Especially, a single mitochondrial gene, such as the cytochrome c oxidase subunit I gene ( COI ), can be used as an effective biological species identification system 9 , 17 and can be informative in tracing the movement of a species 18 . This marker can also genetically distinguish closely related marine invertebrate species 12 , despite its short sequence (~ 543 bp). Crandall et al 5 analyzed the demographic history and phylogeographical patterns of N. albicilla and N. plicata .…”