The introduction of the special issue on "eco-evolutionary dynamics" highlights the intimate link between ecological and evolutionary changes, which can occur on the same time scale. Recent theoretical and empirical developments have shown that ecological changes can lead to rapid evolutionary responses, and vice versa. The integration of ecology and evolution is crucial for advancing our understanding of biodiversity maintenance. The issue brings together biologists from various backgrounds to explore eco-evolutionary dynamics, focusing on three main categories: (1) effects of genotypes and phenotypes on population dynamics, (2) interactions between environmental and genetic variation, and (3) consequences of contemporary evolution on community composition and ecosystem processes. Historical developments in the field are reviewed, emphasizing the reciprocal causal pathway between ecology and evolution. The issue also addresses key questions such as how evolution influences demography, how ecological variables influence the potential for evolution, and when evolution will influence community and ecosystem variables. Finally, the challenges for future research are discussed, including the need for a general theoretical framework, quantifying eco-evolutionary dynamics in natural populations, and overcoming traditional views that separate ecological and evolutionary processes.The introduction of the special issue on "eco-evolutionary dynamics" highlights the intimate link between ecological and evolutionary changes, which can occur on the same time scale. Recent theoretical and empirical developments have shown that ecological changes can lead to rapid evolutionary responses, and vice versa. The integration of ecology and evolution is crucial for advancing our understanding of biodiversity maintenance. The issue brings together biologists from various backgrounds to explore eco-evolutionary dynamics, focusing on three main categories: (1) effects of genotypes and phenotypes on population dynamics, (2) interactions between environmental and genetic variation, and (3) consequences of contemporary evolution on community composition and ecosystem processes. Historical developments in the field are reviewed, emphasizing the reciprocal causal pathway between ecology and evolution. The issue also addresses key questions such as how evolution influences demography, how ecological variables influence the potential for evolution, and when evolution will influence community and ecosystem variables. Finally, the challenges for future research are discussed, including the need for a general theoretical framework, quantifying eco-evolutionary dynamics in natural populations, and overcoming traditional views that separate ecological and evolutionary processes.