Phylogeography of Tetrancistrum nebulosi (Monogenea, Dactylogyridae) on the host of mottled spinefoot (Siganus fuscescens) in the South China Sea, inferred from mitochondrial COI and ND2 genes

Abstract

To examine the phylogeographical pattern of Tetrancistrum nebulosi (Monogenea, Dactylogyridae) in the South China Sea, fragments of mitochondrial cytochrome c oxidase subunit I and NADH dehydrogenase subunit 2 genes were obtained for 220 individuals collected from 8 localities along the southeast coast of China and 1 locality in Terengganu, Malaysia. Based on these two genes, two and three distinct clades with geographic signals were revealed on the phylogenetic trees respectively. The divergence between these clades was estimated to occur in the late Pleistocene. Analysis of molecular variance and pairwise F_ST suggested a high rate of gene flow among individuals sampled from the Chinese coast, but with obvious genetic differentiation from the Malaysian population. Mismatch distribution and neutrality tests indicated that the T. nebulosi population experienced expansion in Pleistocene low sea level periods. Vicariance was considered to account for the genetic divergence between Chinese and Malaysian populations, while sea level fluctuations and mainland-island connections during glacial cycles were associated with the slight genetic divergence between the populations along the mainland coast of China and those off Sanya. On the contrary, oceanographic circulations and host migration could lead to genetic homogeneity of populations distributed along the mainland coast of China.

Keywords:

• COI
• Monogenea
• ND2
• pleistocene isolation
• Tetrancistrum nebulosi

Acknowledgements

We would like to thank Yang Chaopin for their assistance with sample collection, and Zhang Guangzhen, Yang Yang and Liang Jingzhen for their help during the experiment.

Declaration of interest

There are no conflicts of interest for the present paper. The authors are responsible for the content and writing of the paper. This work was funded by National Natural Science Foundation of China (No. 31072215) and Science Foundation of the State Key Laboratory of Biocontrol, Sun Yat-sen University, China (SKLBC10B04).