Genetic diversity of five Kobresia species along the eastern Qinghai-Tibet plateau in China

Abstract

Plants of the genus Kobresia are alpine grass species of high ecological and economic importance. Vegetative growth is the dominant means of reproduction for the Kobresia. Studies suggest that substantial vegetative growth can reduce genetic diversity and renders populations less able to buffer changing and extreme conditions. Kobresia are dominant species in the Qinghai-Tibet plateau in China where they face harsh conditions and frequent disturbance. The genetic diversity of five Kobresia species (K. humilis, K. royleana, K. kansuensis , K. tibetica and K. setchwanensis) from the Qinghai-Tibet plateau was assessed. The results reveal high genetic diversity at the population level for all of the species and there does not appear to be a relationship between altitude and genetic diversity. AMOVA analysis shows that most genetic variability resides among individuals within populations, whereas only a minor portion is found among populations. Of the five species, K. royleana and K. kansuensis have the highest levels of gene flow and the lowest genetic differentiation. While K. setchwanensis has the lowest gene flow and the greatest genetic differentiation. The level of gene flow between populations and the mating system play a critical role in the genetic structure of these Kobresia populations. Despite the predominance of vegetative growth enough sexual reproduction occurs to maintain the relatively high genetic diversity in Kobresia populations.

Restoration prospects for Heitutan degraded grassland in the Sanjiangyuan

“…The warming of the regional climate over the last 40 years in the Sanjiangyuan is not disputed (Li et al 2006;Chen et al 2007), with a significant increase in average annual temperature over the period 1961 to (Li et al 2006. Mean annual temperature in 2003 was the highest on record, 1.4 o C higher than the average across the previous 30 years.…”

“…When yak grazing is either continuous or combined with grazing by sheep and horses, the unavoidable outcomes are the widespread depletion of surface turf/sod or wetlands, the proliferation of short pasture dominated by sedges (e.g. Kobresia; see Zhao et al 2006), the disabling of aquifers, and, eventually, a shift to a degraded Heitutan landscape. These ecological conditions greatly expand habitats capable of supporting high populations of small mammals, which in turn aggravate the natural resource problems further.…”

“…Mean annual temperature in 2003 was the highest on record, 1.4 o C higher than the average across the previous 30 years. As temperature adjustments are most marked in autumn and winter, the annual variation in temperature has also decreased (Li et al 2006;Chen et al 2007). Mean annual precipitation in the Sanjiangyuan from 1961 to 2004 decreased slightly.…”

“…It is especially difficult to restore the sod in areas dominated by degraded ground and associated soil erosion, because the dominant Cyperaceae species (Kobresia spp. ; see Zhao et al 2006) are slow growing (Li et al 2010b). Given the challenges faced in efforts to restore Heitutan, management efforts may be best served by targeting areas of moderate degradation, promoting recovery mechanisms that reduce the risk that such areas will be transformed into more degraded Heitutan ( Figure 5).…”

Comparative genetic diversity and genetic structure of three chinese silkworm species Bombyx mori L. (Lepidoptera: Bombycidae), Antheraea pernyi Guérin-Meneville and Samia cynthia ricini donovan (Lepidoptera: Saturniidae)

“…A PPB around 50% is regarded as high genetic diversity (Zhao et al 2006). Therefore, the results reported here revealed high genetic diversity at the species level for A. pernyi (PPB = 78.57%; h = 0.2666; I = 0.3983) and B. mori (PPB = 61.54%; h = 0.2654; I = 0.3835), whereas low genetic diversity for the Chinese populations of S. cynthia ricini (PPB = 37.97%; h = 0.1407; I = 0.2079).…”