Evenness measures the similarity in abundance across species in an ecological community. In a perfectly even community, all species have the same abundance. In a very uneven community, a few species are common and most species are rare. Although the concept of evenness has been applied in ecology for over 60 years, it has recently come under fire. In a Perspective piece just published in Ecology Letters, Ryan explores the theoretical foundations of evenness indices and their usefulness in furthering productive research programmes. He concludes that, despite some limitations, evenness is still a useful concept in ecology.

Chisholm, R. A. 2026. The usefulness of evenness. Ecology Letters (in press)