Passy Sophia I
Am Nat. 2016 Apr;187(4):502-16. doi: 10.1086/685424. Epub 2016 Mar 3.
The hollow-shaped species abundance distribution (SAD) and its allied rank abundance distribution (RAD)-showing that abundance is unevenly distributed among species-are some of the most studied patterns in ecology. To explain the nature of abundance inequality, I developed a novel framework identifying environmental favorability, which controls the balance between reproduction and immigration, as the ultimate source and species stress tolerance as a proximate factor. Thus, under harsh conditions, only a few tolerant species can reproduce, while some sensitive species can be present in low numbers due to chance immigration. This would lead to high abundance inequality between the two groups of species. Under benign conditions, both groups can reproduce and give rise to higher abundance equality. To test these ideas, I examined the variability in the parameters of a Poisson lognormal fit of the SAD and a square root fit of the RAD in diatom and fish communities across US streams. Indeed, as environmental favorability increased, more sensitive forms were able to establish large populations, diminishing the abundance disparity between locally common and rare species. Finally, it was demonstrated that in diatoms, the RAD belonged to the same family of relationships as those of population density with body size and regional distribution.
空心形状的物种丰度分布（SAD）及其相关的秩丰度分布（RAD）（表明丰度在物种间分布不均）是生态学中研究最多的一些模式。为了解释丰度不平等的本质，我开发了一个新框架，将控制繁殖和迁入之间平衡的环境适宜性确定为最终来源，并将物种胁迫耐受性作为一个直接因素。因此，在恶劣条件下，只有少数耐受性物种能够繁殖，而一些敏感物种可能由于偶然迁入而数量较少。这将导致两组物种之间的丰度高度不平等。在良性条件下，两组物种都能繁殖并产生更高的丰度平等性。为了验证这些观点，我研究了美国溪流中硅藻和鱼类群落的SAD的泊松对数正态拟合参数以及RAD的平方根拟合参数的变异性。确实，随着环境适宜性的增加，更多敏感物种能够建立大量种群，减少了本地常见物种和稀有物种之间的丰度差异。最后，结果表明，在硅藻中，RAD与种群密度与体型和区域分布的关系属于同一关系家族。
