The Origins’ of Neocaridina


Population diversity of N. davidi in Taiwan

A total of 44 N. davidi COI haplotypes (641 bp) from 263 sequences were defined by 53 variable sites and 35 phylogenetically informative sites. The nucleotide sequences were A + T rich (60.0%). The mean COI haplotype diversity in each population was 0.47 (range: 0.00 to 1.00) (Table 1). The estimates of the current (θπ) and historical (θω) genetic diversity of each population indicated that most populations showed a pattern of decline (θπ < θω) (Table 1). A comparison of the fixation indices NST and GST revealed that NST was larger than GST (0.72 and 0.47, respectively; Table 3). This result suggested a very weak relationship between phylogeny and geography.

Among the 44 COI haplotypes, eleven haplotypes (D1-D11) were shared between two or more populations (Table 1). The most widespread haplotype was D9, which was distributed among nine populations. Among the 26 sampling populations, only one population (DA) had more than two shared haplotypes, and six populations (ML, DT, DJ, SA, DZ and GF) did not have any shared haplotypes. The population DA had the most shared haplotypes (D2, D3 and D9; Table 1). In the phylogenetic analyses, the haplotype trees reconstructed with different methods (ML and BI) were identical. In the BI tree (Fig. 5a), 44 mtDNA haplotypes fell into three lineages (ND1-ND3). Lineage ND1 included 15 populations that were widespread in Taiwan, lineage ND2 contained five populations in northern Taiwan, and lineage ND3 contained nine populations in northern, eastern and southern Taiwan (Fig. 5a).

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Fig. 5
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To detect the ancestral region of N. davidi in Taiwan, all sampling populations were sorted into five regions as in previous studies: northern (A), central (B), southern (C), northeastern (E), and eastern (D) Taiwan [1032]. The results of the S-DIVA analysis produced a scenario with dispersion and vicariance events that shaped the current distribution patterns of N. davidi in Taiwan (Fig. 5a). The ancestral populations of N. davidi were distributed in northern, central and northeastern Taiwan and then diverged and dispersed widely in Taiwan.

Population diversity of N. ketagalan

A total of 27 N. ketagalan haplotypes from 126 sequences were defined by 44 variable sites and 36 phylogenetically informative sites. The nucleotide sequences were A + T rich (58.2%). The mean COI haplotype diversity in each population was 0.49 (range: 0.00 to 0.75) (Table 1). The estimates of θπ and θω indicated that this species showed a pattern of decline (θπ < θω) (Table 1). A comparison of the fixation indices NST and GST revealed that NST was larger than GST (0.82 and 0.44, respectively; Table 3). This result suggested a weak relationship between phylogeny and geography.

Among the 27 haplotypes, four haplotypes (K1-K4) were shared between two or more populations (Table 1). Among these ten sampling populations, two populations (XH and DA) had two shared haplotypes, and four populations (ML, DT, LZ and JG) did not have any shared haplotypes. The haplotype trees reconstructed with different methods (ML and BI) were identical. In the BI tree (Fig. 5b), 27 mtDNA haplotypes fell into three lineages (NK1-NK3). Lineage NK1 included three populations in northern Taiwan; lineage NK2 contained seven populations in northern and central Taiwan; lineage NK3 only contained one population (DS) in northern Taiwan (Fig. 5b). To detect the ancestral region, all sampling populations were sorted into three regions, A1, A2, and B (Fig. 5b). Northern Taiwan (A) was divided into two sub-regions (A1 and A2) by the Taoyuan Plateau (Fig. 1). The results of the S-DIVA analysis produced a scenario with vicariance and dispersal events that shaped the current distribution patterns (Fig. 5b). The ancestral populations of N. ketagalan were distributed north of the Taoyuan Plateau and then dispersed southward.

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