关键词: 拟步甲, 生态位宽度, 生态位重叠, 种间联结, 冲积扇, 贺兰山

Abstract:  【Aim】 The darkling beetle plays an important role in maintaining biodiversity and ecosystem function in desert semi-desert habitats. This study aims to reveal the niche and interspecific associations of darkling beetles so as to lay a basis for studying the mechanism of community construction in desert grasslands of alluvial fans. 【Methods】 A field survey was carried out to investigate darkling beetle communities using pitfall in a desert grassland of alluvial fans in Helan Mountain, northwestern China from May to October 2019. The sampling transect of about 200 m×200 m was divided equally into 100 square plots. Based on 2×2 contingency table analysis, niche breadth, niche overlap, variance ratio test, Chi-square test, association coefficient (AC), percentage of cooccurrence (PC), Ochiai index (OI), Dice index (DI) and Spearman rank correlation coefficient, we analyzed the niche and interspecific association of darkling beetle species at a small scale. 【Results】 A total of 1 086 individuals of adult darkling beetles belonging to 10 species from 7 genera were collected. Microdera kraatzi kraatzi, Anatolica pandaroides and Anatolica planata were the dominant species in the whole community. The spatial niche breadth of A. planata was the largest, the temporal niche breadth of Scytosoma pygmaeum was the largest and the temporal-spatial niche breadth of M. kraatzi kraatzi was the largest. The temporal, spatial and temporal-spatial niche breadth of Opatrum subaratum was the smallest, which was at a weak competitive position. The results of niche breadth clustering showed that M. kraatzi kraatzi, A. pandaroides, S. pygmaeum and S. dissilimarginis are wide niche species. The temporal niche overlaps of species pairs of darkling beetles were more significant than their spatial niche overlaps. The variance ratio and W test results showed that there existed a significantly positive interspecific association. The results of the Chi-square test, association coefficient (AC), and the Spearman rank correlation coefficient showed that the ratio of species pairs of the positive and negative associations was greater than 1 and the overall correlation tended to be positive. The percentage of co-occurrence (PC), Ochiai index and Dice index indicated that there was a significant positive correlation among the dominant species M. kraatzi kraatzi, A. pandaroides and A. planata. According to constellation diagram of the Spearman rank correlation coefficient network, the 10 species were divided into three ecological species groups. 【Conclusion】 The dominant species have a wide niche, the temporal niche and spatial niche of species vary inconsistently, and the niche overlaps of species pairs with significant positive connection are also relatively higher. Clustering of ecological species groups reflects the differences in the ecological adaptability of species pairs. The results provide references for studying the succession of darkling beetle community in desert grasslands of alluvial fans.

Key words: Tenebrionidae, niche breadth, niche overlap, interspecific association, alluvial fans, Helan Mountain