Genetic variability and divergence of Neutrodiaptomus tumidus Kiefer 1937 (Copepoda: Calonida) among 10 subpopulations in the high mountain range of Taiwan and their phylogeographical relationships indicated by mtDNA COI gene

Shuh-Sen Young,Yan-Ying Lee,Min-Yun Liu

doi:10.1186/s40555-014-0022-6

Abstract

In the mountain area of Taiwan, we investigated 10 subpopulations of Neutrodiaptomus tumidus Kiefer 1937 living in isolated alpine ponds or lakes. We used mitochondrial DNA cytochrome C oxidase subunit I (COI) sequence as molecular marker to investigate the population genetic structure and their phylogeographical relationships. We obtained 179 sequences from 10 subpopulations and found 94 haplotypes. Nucleotide composition was AT-rich. Haplotype diversity (Hd) and nucleotide diversity (π) indicated significant genetic differences between subpopulations (Hd = 0.131 ~ 0.990; π = 0.0002 ~ 0.0084); genetic differentiation index (F st) and gene flow index (N m) also exhibited significant genetic diversification between subpopulations (F st = 0.334 ~ 0.997; N m = 0 ~ 1). Using Tajima’s D and Fu and Li’s D* and F* as neutrality tests, we found that the nucleotide variation within the population was consistent with the neutral theory except in the JiaLuoHu subpopulation. The JiaLuoHu subpopulation significantly deviated from the neutral theory and was speculated to have experienced a bottleneck effect. According to the phylogenetic tree, these alpine lake subpopulations could be divided into four phylogroups (northern region, Xueshan group, central region, and southwestern region). Xueshan group contains one subpopulation, DuRongTan, which is a unique group relative to other groups. It is close to northern group geographically but closer to southwestern group genetically. According to AMOVA, the major genetic variation came from different geographical distribution of subpopulations. Molecular clock estimates that the northern and southern regional divergence time was about 2.2 ~ 3.9 MYA, when the Central Mountain Range uplift (3 ~ 5 MYA) caused the population of N. tumidus to be segregated into northern and southern parts. Significant genetic divergence between each subpopulation of N. tumidus was found in this study. This result indicated the low dispersion ability of planktonic copepods with limited gene flow between each subpopulation.

Highlights

In the mountain area of Taiwan, we investigated 10 subpopulations of Neutrodiaptomus tumidus Kiefer 1937 living in isolated alpine ponds or lakes
We report the levels of genetic variability and divergence within and among 10 subpopulations of N. tumidus isolated in lakes and ponds in the high mountain area
In this study, we found significant genetic divergence between each subpopulation of N. tumidus isolated in high mountain ponds or lakes

Summary

Introduction

In the mountain area of Taiwan, we investigated 10 subpopulations of Neutrodiaptomus tumidus Kiefer 1937 living in isolated alpine ponds or lakes. After the formation of the Central Mountain Range, other series of mountain formations formed Xueshan Range, Yushan Range, and Alishan Range (Figure 1). Today these four major mountain systems cover the two third of the land area of Taiwan; the Central Mountain Range stretches along the central area of island from north to south and off to the east. The northern part of Xueshan Range is more isolated from the main range, and the LanYang River system flows through the deep valley between Xueshan Range and Central Mountain Range and northward into Ilan Bay. DaJia River system runs across middle region of Xueshan Range through the western plain into the Taiwan Strait, with its headwaters near the origin of LanYang River.

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Discussion

Conclusion