DNA sequence variations
The three aligned cpDNA fragments, atp B-rbc L (delete the
poly T), psb A-trn H and psb B-psb H, were 729,
617 and 644 bp in length for C. bifida ; 735, 581 and 644 bp in
length for C. micholitzii , respectively. The 1990 bp combined
cpDNA data set of C. bifida had 22 parsimony-informative
polymorphic sites (S) and identified seven haplotypes (cpH1-cpH7). The
nucleotide diversity per site (π) was 0.00191 and haplotype diversity
(H d) was 0.7184. While, the 1960 bp combined cpDNA data set ofC. micholitzii had 24 parsimony-informative polymorphic sites (S)
and identified 14 haplotypes (cpH8-cpH21). Its nucleotide diversity per
site (π) was 0.00107 and haplotype diversity (H d) was 0.9078. The
haplotype geographical distributions of the two species were presented
in Figure 1a. For C. bifida , two populations in China, XS and SJ,
had three haplotypes respectively and the remaining three populations
(PX, TA and BT) had only one unique haplotype. For C.
micholitzii , population ATT and KON had four haplotypes and the other
five populations only had one unique haplotype.
The length of the five amplified nuclear genes ranged from 520 to 1005
bp (Table 1). All indels were excluded from subsequent analysis. The
genetic diversity indices of C. bifida and C. micholitziiwere showed in Table 1. Recombination events occur frequently in the low
copy nuclear genes. The number of segregating sites and number of
haplotypes of C. micholitzii were generally higher than that ofC. bifida , while nucleotide diversity per site (π) and haplotype
diversity (H d) of C. micholitzii were lower than that ofC. bifida . The haplotype geographic distributions of each gene
for the two species were shown in Figure 1b-f. Results showed that there
is one haplotype (A5) of the PHYP gene and two haplotypes (D6 and
D10) of ATT that shared between C. bifida and C.
micholitzii , and the haplotypes of the other three genes were all
species-specific.