| On Inner-Mongolia Plateau, Reaumuria soongorica distributes in typical steppe, desertification steppe, steppe desert, and typical desert. Along with changes of types of steppe, natural R. soongorica shows diversity in both morphology and genetics. Meanwhile, meteorological factors and soil factors change too. This study worked on population morphology, ISSR genetic diversity characteristics, analysed the reason why R. soongorica showed those gradient changes linking to meteorological factors and soil factors on large scale.In the contrast, we chose4meta-populations in QiPanjing fragmented habitats on ordos plateau, applying both ISSR and SSR molecular markers, compared and analysed genetic diversity of4meta populations in fragmented habitat. The results are as follows:1The highest value of stem length of R. soongorica on Inner-Mongolia Plateau appeared in typical desert, while the lowest one appeared in Dongsu typical steppe. The highest value of canopy size belonged to desertification steppe, while the lowest one belonged to steppe desert. Extrem values of volume were the same as canopy size.Total salt concentrations of R. soongorica maintaining at a high level was higher than soil total salt concentrations as a whole. pH value of R. soongorica was higher than soil pH value, with a significant correlated relationship with pH value of middle soil layer. Total organic carbon of R. soongorica decreased generally, while there was a low value in desertification steppe.2Different soil layers of8R. soongorica sampled sites on Inner-Mongoia Plateau had the same trends of changes of soil factors. That is, soil water contents decreased gradually from transition region of desertification steppe and steppe desert. While from typical steppe to desertification steppe, there was no obvious gradient change law. Total salt concentrations showed a upward-downward-upward-downward-upward trend, with the high value appearing on Dongsu typical steppe, transition region of desertification steppe and tylcal desert, and tylcal desert. pH values of all8R. soongorica sampled sites remained at8.0, with a narrow range. Soil total phosphorus decreased gradually from Dongsu typical steppe to its west, with a narrow range. Soil available phosphorus showed a gradient decrease trend with little difference except that there was a obvious high value on Dongsu typical steppe. Soil N-available was with a trend of downward-upward-downward, in detail, soil N-available fell to valley bottom on desertification steppe. Then the lowest value appeared on typical desert. TOC of soil decreased gradually along with types of steppe changing from typical steppe to typical desert.3The stem length of R. soongorica populations on Inner-Mongolia Plateau significantly correlated with≥10℃accumulated temperature which belonged to meteorological factors(p=0.0051＜0.05), and its interpretation extent was as high as75.49%. Stem length of R. soongorica significantly correlated with10-20cm soil organic carbon; canopy size had significant correlation with0-10cm soil available phosphorus,20-30cm soil N-available and10-20cm soil pH value,, with a degree of explaination of94.51%、4.23%and0.88%respectively; Volume had significant correlation with20-30cm soil water contents and0-1Ocm soil organic carbon, which could explain62.34%and24.11%in degree.4There were316loci applying14primers to do PCR for160samples of8R. soongorica populations, with total percentage of polymorphic loci being100%. At spicies level, observed number of alleies was2.0000, number of effective alleles was1.3955, Nei’s genetic and Shannon diversity index were0.2499and0.3953respectively. Genetic diversity among8R. soongorica populations was0.2499, while within8populations was0.2016, Nei’s genetic differentiation (GST) was0.1931. Analysis of molecular variance(AMOVA) showed that,26.23%genetic differentiation accurred among populations, while73.77%accurred within populations, with FST being0.26233. Gene flow among populations Nm=2.0899, which demonstrated tha there was frequency gene flow among Inner-Mongolia populations. The cluster analysis of8populations did not show the same change rule according to changes of geographic sites, while there was geographic marks, though. Analysis of PCA and UPGMA cluster of all samples also showed that, there was a genetic penetration phenomenon. The genetic distance had no relationship with geographic distance according to Mantel test.5Number of alleles and percentage of polymorphic loci significantly correlated with frost-free days; on the top of that, number of effective alleles, number of alleles, Nei’s diversity, Shannon diversity index and percentage of polymorphic loci all had significant correlation with average water contents of three soil layers.6Both ISSR and SSR for R. soongorica in fragment habitat had high polymorphism. When in consideration of the comparison between them, SSR possess higher resolution than ISSR in total percentage of polymorphic loci, observed number of alleles, number of effective alleles, Nei’s genetic, Shannon diversity index and total genetic differenciation among and within populations. Nei’s genetic distance analysis demonstrated that there was strong difference between ISSR and SSR results. While there also was partial similarity between them, that was, population20and population21cluster to one kind, which should because of their own detecting ranges. Study on genetic diversity of R. soongorica populations on Inner-Mongolia Plateau made a usefull scientific inquiry to declare the relationship between landscape characteristics and inside population micro-evolution such as gene flow and local adaptive. |
PDF Full Text Request