天山西部果子沟地区拟南芥生存群落种间联结性分析

Interspecific associations among main species in the communities with Arabidopsis thaliana occurrence in Guozigou region of the western Tianshan Mountains

采用方差比率法(VR),基于2×2列联表的χ2统计量、Ochiai、Dice和Jaccard联结指数以及去势对应分析(DCA),对天山西部果子沟地区拟南芥(Arabidopsis thaliana)生存群落20个主要物种间的联结特征及拟南芥分布的主要依赖物种进行了分析。结果表明:群落内20个主要物种总体联结方差比率为1.552 3,表现为显著正联结。190个种对中,有108对表现出正关联,82对为负关联;χ2检验有18对表现显著或极显著正关联,有16对表现显著或极显著负关联。有153个种对OI<0.6,但主要优势种间的OI值基本都>0.6。Dice和Jaccard指数也具有相同规律。DCA排序图较直观地表示了种间联结关系,与χ2检验和联结指数对应较好。主要优势种都聚集在排序图中央,种间联结紧密,而次要种则散布于周缘,联结性较弱。20个物种分成3个生态种组,组间区分较为明显。拟南芥与群落主要优势种关系密切,对它们依赖性较强,它们是影响拟南芥分布的主要生物因素;拟南芥与次要物种之间联结性较弱,表明它们生境趋异。总体上,本地区拟南芥生存群落处于相对稳定的发展阶段。

Arabidopsis thaliana is an important model plant in the field of plant biology, and it has been studied in depth in molecular biology, evolutionary genetics, developmental biology etc. , but now the relationship between different ecotypes of A. thaliana and its closely related species, and the related ecological research have become the hotspots. The Tianshan Mountains and its nearby mountains are one of the main distribution regions of A. thaliana and its closely related species in the world. The species resources of A. thaliana and its closely related species shaped under the special habitat are the precious materials to study the evolutionary ecology of A. thaliana. The a- nalysis on interspecific associations can help understand the distribution characteristics and environmental depend- ence of A. thaliana and its closely related species, and it is valuable for revealing the natural selection character of local A. thaliana. The two typical 10 m × 10 m plots （communities） with A. thaliana occurrence were selected in Guozigou region of the western Tianshan Mountains, and the variance ratio （VR） ,X2 test, Ochiai, Dice and Jaccard indices based on the 2 × 2 contingency table, and the detrended correspondence analysis （DCA） were used to ana- lyze the interspecific associations among 20 main species, including the key species which A. thaliana distribution depended on. The results show that the variance ratio （VR） of overall association of 20 main species is 1. 552 3,in- dicating signifcant positive correlation. 108 species pairs show positive correlation in a total of 190 species pairsa- mong 20 species,while the other 82 species pairs are negative correlation. 18 significant positive correlation and 16 species pairs show significant or very species pairs show significant or very significant negative correlation in X2 test. The Ochiai values of 153 species pairs are less than 0.6, but the values among main dominant species are more than O. 6 almost. The Dice and Jaccard indices have the shows the relationships among 20 main species intuitively, and th same regularity as Ochiai index. The DCA figure e result corresponds tox2 test and three association indices obviously. Main dominant species are gathered in the centre of the DCA figure with close association, and the secondary species are scattered in the surrounding with weak association. 20 species can be divided into three ecological species groups with obvious inter-group distinction. A. thaliana is closely related to and strongly depend- ent on the main dominant species which are the dominant biological factors affecting the existence and distribution of A. thaliana populations, such as Myosotis sylvatica, Trigonella arcuata and Cleistogenes squarrosa. The associa- tions between A. thaliana and the secondary species are weak,indicating they have a divergence of habitat. Compared with other distribution sites of A. thaliana in the northern Tiansn Mountains,the Guozigou region has more precipitation, particular environment and species, therefore the special interspecific association and dependence were formed through the long-term evolution and adaptation. In conclusion,A, thaliana communities in Guozigou region of the western Tianshan Mountains are in a relatively stable development stage.