Literature review
We searched the Web of
Science for studies plotting the relationship between the abundance of
an organism and an environmental factor at large geographical scales. We
used the following terms: (Abundan* OR ”population size” OR ”population
trend” OR density) AND (biogeography OR Macroecology OR “large extent”
OR “large scale”) on November 25th, 2020. Then, we selected literature
from ecology and biogeography journals together with the
multidisciplinary journal Nature (see the list of journals in
Appendix S1), returning 4,700 articles (Fig 2A).
From those, we conducted a
title-based filtering that resulted in 744 publications
(~18% of initial articles). Then, we reviewed the
articles’ main text in search for at least one plot relating the
abundance of an organism (or an equivalent measure, such as population
density) against a continuous environmental predictor.
For those that showed the data
points in the plot, we visually classified the shape of the
abundance-environment relationship as line-shaped, polygon-shaped, or
unclear – in cases where it was not possible to clearly identify the
point cloud shape due to low sample sizes or representation means. We
also identified the statistical method used to estimate the relationship
and if there was any mention to the LoM. Lastly, we recorded the
taxonomic group, the habitat, and the geographical region of study.