[For the David Penny and Mike Hendy Symposium]
David Penny and Mike Hendy have made a remarkable contribution to the development of evolutionary biology by helping to develop not only the tools but also the insight needed to connect biomolecular change at the genomic level to microevolutionary change at the population level to the generation of biodiversity. These different levels of evolutionary change have commonly been studied by biologists from different disciplines, with geneticists and biochemists investigating mutation, population biologists and ecologists studying population level processes, and palaeontologists and systematists revealing patterns of biodiversity. But Penny and Hendy have contributed to the emergence of a new field whereby we can consider all of these levels of evolutionary change within a single framework, through the analysis of DNA sequences. Through molecular phylogenetic analysis, we can link change at the biochemical level to species characteristics and biodiversity generation, highlighting the continuity of processes of mutation (generation of variation), microevolution (population divergence) and macroevolution (lineage diversification).