Are species most abundant in the centre of their climatic niches?

Massive study fails to find support for this hypothesis–but is criticized of methodological problems preventing a sound conclusion

Data resources used via GBIF : 20,210,035 species occurrences

The abundant centre hypothesis represents the phenomenon that a species is most abundant at the centre of its geographical range or climatic niche. However intuitive this may sound, the empirical support for this claim is rather weak.

In a large data analysis, researchers from UC Davis tested the hypothesis by examining the relationships between abundance and distance to centre of range or niche for more than 1,600 species of birds, mammals, fish and trees. Relying on GBIF-mediated species occurrences to define the range and niche centroids, the authors’ analyses found only slight correlations for some species–both positive and negative–while the majority of tested species showed no relationship at all.

Contrasting previous findings, the results of the study, however, has since been questioned by other researchers, arguing that a number of methodological problems in fact hinders a robust conclusion. While the original paper represents the largest-scale analysis of species spatial abundance patterns, the jury on abundant centres still appears hung.

Dallas T, Decker RR and Hastings A (2017) Species are not most abundant in the centre of their geographic range or climatic niche. Ecology Letters. Wiley 20(12): 1526–1533. Available at: https://doi.org/10.1111/ele.12860.

Soberon J, Peterson AT and Osorio-Olvera L (2018) A comment on ‘Species are not most abundant in the center of their geographic range or climatic niche’. Cold Spring Harbor Laboratory. Available at: https://doi.org/10.1101/266510.