Benedetti-Cecchi Lisandro, Bertocci Iacopo, Vaselli Stefano, Maggi Elena, Bulleri Fabio
Dipartimento di Biologia, Università di Pisa, Pisa, Italy.
PLoS One. 2008 Jul 23;3(7):e2777. doi: 10.1371/journal.pone.0002777.
Neutral models and differential responses of species to environmental heterogeneity offer complementary explanations of species abundance distribution and dynamics. Under what circumstances one model prevails over the other is still a matter of debate. We show that the decay of similarity over time in rocky seashore assemblages of algae and invertebrates sampled over a period of 16 years was consistent with the predictions of a stochastic model of ecological drift at time scales larger than 2 years, but not at time scales between 3 and 24 months when similarity was quantified with an index that reflected changes in abundance of rare species. A field experiment was performed to examine whether assemblages responded neutrally or non-neutrally to changes in temporal variance of disturbance. The experimental results did not reject neutrality, but identified a positive effect of intermediate levels of environmental heterogeneity on the abundance of rare species. This effect translated into a marked decrease in the characteristic time scale of species turnover, highlighting the role of rare species in driving assemblage dynamics in fluctuating environments.
中性模型以及物种对环境异质性的差异响应为物种丰富度分布和动态提供了互补的解释。在何种情况下一种模型比另一种模型更具优势仍是一个有争议的问题。我们表明，在长达16年的时间里对岩石海岸藻类和无脊椎动物群落进行采样，随着时间推移相似度的衰减，在时间尺度大于2年时与生态漂变随机模型的预测一致，但在3至24个月的时间尺度上不一致，此时相似度是用一个反映稀有物种丰度变化的指数来量化的。进行了一项野外实验，以检验群落对干扰时间方差变化的响应是中性还是非中性的。实验结果并未否定中性，但确定了中等水平的环境异质性对稀有物种丰度有积极影响。这种影响转化为物种更替特征时间尺度的显著缩短，突出了稀有物种在波动环境中驱动群落动态的作用。
