With inspiration from the past

Sometimes it’s worth bringing good old science back into the light. Hideyuki Doi and Terutaka Mori were inspired by two papers from 1932 and 1953 about species abundance distirbution and brought them into modern days’ science. Read the paper “The discovery of species–abundance distribution in an ecological community” on Early View. Here’s the author’s own background story:

Species–abundance distribution (SAD), representing relative species abundance, is one of the most basic descriptions of an ecological community. The description can represent more detailed attributes of the community than species richness. Universal observations that few species in a community are dominant, but that many more species are rare, can be neatly encapsulated in a SAD, but not represented by species richness.

Prof. Isao Motomura (1904–1981, photo) first found a SAD pattern for some animal communities and then published a notable paper in 1932. Motomura (1932) described SAD in the following way: ‘In a community, there are generally many more species with relatively low abundances. When the species found within a quadrat are ranked according to abundance (i.e. the order of dominance in the community), a definite graphic pattern is observed between the rank and abundance of species’. He found that a straight line is produced when logarithm of abundance is plotted against rank, and then fitted observed SAD to “geometric series”. Motomura’s study is the first discovery of a SAD pattern, but has often been overlooked or incorrectly cited, probably due to being published in Japanese.

In this article, we in-deep introduce the works of Motomura and the subsequent research history of SAD. Specifically, we also introduce the work of Numata et al., another Japanese paper, which provided the biological explanation for Motomura’s model of SAD. Numata et al. (1953) showed that Motomura’s model (i.e. geometric series) is explained by supposing that species occupy the available area according to the rank of a set of ability for individual and species survival (i.e. reproduction, competition, etc.). Therefore, they provided biological explanations with a deductive approach for Motomura’s model in which an inductive statistical approach was employed. We believe that the field of SAD is increasing in importance and activity, because SAD has proven to be one of the most important fundamental tools in community ecology and management. Motomura (1932) paper also includes an important suggestion for ecologists: ‘In a natural ecosystem, it is very unusual to find such geometric series for the abundances of species coexisting in a habitat’. The finding of such a surprising pattern in ecological communities therefore represents a frontier of ecological research. Our motivation for finding a new general rule in ecology is highly recommended.