2.5 Statistical analysis of the results
The Kruskal-Wallis H-test and Mann-Whitney U-test values are shown in Supplementary Table 11. In this study, only SSRs in the chloroplast genome in its IGS and LSC regions, as well as single-nucleotide SSRs in the whole chloroplast genome, were considered. There were significant differences in the number, relative abundance, relative density, and GC content of SSRs when the eight species of Cyatheaceae were divided into three genera (Kruskal-Wallis H, P < 0.05). WhenGymnosphaera was included in the genus Alsophila , they were divided into two genera, and only the difference in the GC content was significant (Table 4). The number of SSRs in other regions of the chloroplast genome and the number of SSRs of other unit lengths were small, so they are not discussed in this study. The clustering results of the number, relative abundance, relative density, and GC content of the SSRs in the chloroplast genomes and their IGS regions and the single-nucleotide SSRs of the whole chloroplast genome of the eight species of Cyatheaceae (Figure 5) showed that the eight species were divided into two groups. That is, Sphaeropteris brunoniana ,Sphaeropteris lepifera , Alsophila spinulosa andAlsophila costularis were in a group, and Alsophila denticulata , Alsophila podophylla , Alsophila metteniana , and Alsophila gigantea were in a group.
Table 4 Significance test of the number, relative abundance, relative density, and GC content of SSRs in the whole chloroplast genome, IGS, and LSC and mononucleotide SSRs in the whole chloroplast genome of the eight Cyatheaceae species