At a glance, most species seem adapted to the environment in which they live. Yet species relentlessly evolve, and populations within species evolve in different ways. Evolution, as it turns out, is much more dynamic than biologists realized just a few decades ago. In "Relentless Evolution," John N. Thompson explores why adaptive evolution never ceases and why natural selection acts on species in so many different ways. Thompson presents a view of life in which ongoing evolution is essential and inevitable. Each chapter focuses on one of the major problems in adaptive evolution: How fast is evolution? How strong is natural selection? How do species co-opt the genomes of other species as they adapt? Why does adaptive evolution sometimes lead to more, rather than less, genetic variation within populations? How does the process of adaptation drive the evolution of new species? How does coevolution among species continually reshape the web of life? And, more generally, how are our views of adaptive evolution changing? "Relentless Evolution" draws on studies of all the major forms of life--from microbes that evolve in microcosms within a few weeks to plants and animals that sometimes evolve in detectable ways within a few decades. It shows evolution not as a slow and stately process, but rather as a continual and sometimes frenetic process that favors yet more evolutionary change.

Traditional ecological approaches to species evolution have frequently studied too few species, relatively small areas, and relatively short time spans. In "The Coevolutionary Process," John N. Thompson advances a new conceptual approach to the evolution of species interactions--the geographic mosaic theory of coevolution. Thompson demonstrates how an integrated study of life histories, genetics, and the geographic structure of populations yields a broader understanding of coevolution, or the development of reciprocal adaptations and specializations in interdependent species.
Using examples of species interactions from an enormous range of taxa, Thompson examines how and when extreme specialization evolves in interdependent species and how geographic differences in specialization, adaptation, and the outcomes of interactions shape coevolution. Through the geographic mosaic theory, Thompson bridges the gap between the study of specialization and coevolution in local communities and the study of broader patterns seen in comparisons of the phylogenies of interacting species.