Influence of small-scale habitat patchiness on the genetic diversity of the Korean endemic species Saussurea chabyoungsanica (Asteraceae)

Abstract

The level of genetic diversity within and among six populations of Saussurea chabyoungsanica, a Korean endemic plant distributed as small patches in limestone regions, was analyzed using ISSR markers. A correlation analysis was conducted to understand the influence of the species' ecological characteristics on the genetic diversity parameters. The genetic patch widths were estimated through a spatial genetic structure (SGS) analysis. The genetic diversity at the species level was quite compatible (P = 90.5%; h = 0.352), but reduced by almost half (P = 45.6%; h = 0.173) at the population level. The genet diversity was high at the species level (Gm/N = 0.528; DG = 0.980), but it varied among the populations. The high level of interpopulational genetic differentiation (ФST = 0.532) appeared to have been influenced by the genetic drift because of the small population size. The flowering rate was positively correlated with each genetic parameter. On the other hand, the coverage of the canopy layer and the number of shoots per bunch were negatively correlated with the genetic parameters. The SGS was significant, but its intensity was low (Sp = 0.021). Sexual propagation enhanced the SGS magnitude within a short distance (<1 m), but not the SGS pattern. Thus, the genetic patch was about 4 m wide at both the genet and ramet levels. The small and isolated populations of S. chabyoungsanica could be at risk of extinction due to their continuously shrinking population sizes and the accelerated genetic drift. Therefore, several specific conservation measures were suggested.