Stipa grandis steppe, a tussock steppe in the Mid-Asian grassland of Euro-Asian Steppe Region, is one of the representative formations of the typical steppes in Inner Mongolia, China. Increasing awareness of diversity reduction has brought about the increased interest in the studies of dominant species like S. grandis, both at home and abroad. A study on genetic diversity and genetic structure of the dominant species will provide a better measure of the ecosystem’s genetic health, as well as provide a scientific basis for its conservation and utilization. However, there have only been a few studies on S. grandis genetic diversity so far and studies on the association with ecological factors are even rare. Therefore, it is necessary to thoroughly investigate the genetic characters of S. grandis.
In the present study, genetic diversity in random amplified polymorphic DNAs (RAPD) was studied for 90 genets of the S. grandis, from 5 natural populations sampled in Xilingol steppe. Sixteen oligonucleotides screened from 100 random decamer primers were used to amplify 310 scorable RAPD loci that were all polymorphic.
By analysis of RAPD data with POPGENE software, it was found that high level of genetic diversity existed in S. grandis populations. Most variation existed within populations and 28% variation existed among populations. By Pearson correlation analysis, significant correlations were found between gene diversity indexes and temperature factors (≥10℃cumulative temperature in a year, annual mean temperature and mean temperature in January), and all diversity indexes showed significant correlations with mean temperature in January. Mantel tests showed that there was no significant correlation between Nei’s unbiased genetic distance and geographic distance of S. grandis populations, but positive and significant correlations existed between Nei’s genetic distance and several climatic divergences in pair-wise S. grandis populations (p<0.05), suggesting that natural selection of climatic variation (mainly in precipitation and temperature) resulted in the adaptive RAPD eco-geographic differentiation.