Fluctuating and directional asymmetry in species abundance.

*In order to compare the FA level among the groups, we used the non-parametric Kruskal-Wallis test.**In order to test for directional asymmetry, we used one sample two tailed t-test of against zero, separately for each one of the different groups.***We tested for normality of the signed asymmetry using the Shapiro-Wilk test.为比较各组的FA水平，我们采用了非参数克鲁斯卡尔-沃利斯检验（Kruskal-Wallis test）。为检验定向不对称性，我们针对每个不同组别分别采用了以零为基准的单样本双侧t检验。我们采用夏皮罗-威尔克检验（Shapiro-Wilk test），对符号化不对称性的正态性进行了检验。