The promise and pitfalls of β-diversity in ecology and conservation

A key challenge in ecology and conservation is to determine how processes at different scales create variation in community composition (beta-diversity). In this issue, Olden & Halme show that grazers increase beta-diversity through multiple processes at different scales. We discuss how beta-diversity can elucidate fundamental processes of community assembly, challenges in linking processes to patterns, and unresolved questions across scales.