3.2 Clonal diversity and structure of diploid and tetraploid
Both the diploid and tetraploid of C. udensis were clonal
populations. There were 89 and 46 genets in tetraploid and diploid,
respectively. For this species, it also presented relatively higher
clonal diversity (Table 4).
The average clone size (N /G ) of the tetraploid was 1.146,
the Simpson diversity index (D ) and Fager evenness index
(E ) were 0.4695 and 0.6863, respectively. Correspondingly, these
parameters for the diploid were 1.109, 0.3741 and 0.4612 respectively,
indicating that the tetraploid had higher clonal diversity than the
diploid.
No shared genotype was found between diploid and tetraploid (Table 4).
The analysis of variance between Simpson diversity index (D ) and
Fager evenness index (E ) showed that there were significant
differences in clonal diversity between diploid and tetraploid
(P <0.05).
There were no dominant clones in the C. udensis diploids and
tetraploids of the Hualongshan Mountains. The diploids consisted of 46
genotypes (genets), of which three genets had two clonal ramets, and one
genet had three clonal ramets, while the other 42 genets had only a
single clonal ramet. For the tetraploid, there was 89 genotypes
(genets), of which three genets had two clonal ramets, and two genets
had three clonal ramets, while the other 78 genets had only a single
clonal ramet (Fig. 3). Therefore, both the diploids and tetraploids were
polyclonal. Further, no identical individual genotype was found between
the different ploidies, which verified that differentiation occurred
between the diploids and tetraploids.
It is worth noting that there was differentiation in the clonal
reproduction characteristics between the diploids and tetraploids. In
the diploids, the numbers of clones (number of genets) were relatively
lower, and the distribution of clones or genets was scattered. While for
the tetraploids, the distribution of genets was relatively close and
dense, which indicated higher clonal diversity.
All of the sample C. udensis diploid and tetraploid individuals
were amplified by PCR using SSR markers (Table 1). Finally, 51 clear and
stable DNA fragments were obtained for eight pairs of SSR primers. The
sizes of the DNA fragments were from 350-750 bp. No linkage
disequilibrium loci were found. Among the 51 bands, 40 bands were
polymorphic. The percentage of polymorphic loci (PPL ) was 78.4%,
in addition, Nei’s gene diversity index H was 0.2358, and the Shannon
information diversity index I was 0.6337. All these results confirmed a
high level of genetic diversity in C. udensis (Table 4).
Three genetic diversity indices of the tetraploid were PPL =
68.5%, H = 0.2332, and I = 0.3416, respectively, which were slightly
higher than that of the diploid (PPL = 63.5%, H = 0.2127, and I
= 0.3012) (Table 2). It showed that the genetic diversity of the
tetraploid was slightly higher than that of the diploid.
The gene differentiation coefficient G ST between
the diploid and tetraploid was 0.6193, which indicated that 61.93% of
the total genetic diversity existed between the different ploidies, and
the genetic variation within different ploidies was 38.07%. This was
consistent with the results of AMOVA analysis, namely, greatest genetic
variation occurred between the diploid and the tetraploid (Table 5).