1. Department of Ecology and Evolutionary Biology, Earth and Marine Sciences Building, University of California, Santa Cruz, California 95064, USA
2. School of Life Sciences, Washington State University, Pullman, Washington 99164, USA

Correspondence to: John N. Thompson¹ Correspondence and requests for materials should be addressed to J.N.T. (e-mail: Email: thompson@biology.ucsc.edu).

Abstract

Coevolution of species is one of the major processes organizing the Earth's biodiversity. Recent coevolutionary theory has indicated that the geographic structure of species has the potential to impose powerful and continuing effects on coevolutionary dynamics, if that structure creates selection mosaics and coevolutionary hotspots across landscapes^{1, 2, 3, 4, 5, 6, 7}. Here we confirm that current coevolutionary selection in interspecific interactions can be highly divergent across both narrow and broad geographic scales, thereby fuelling continuing coevolution of taxa. Study of a widespread plant–insect interaction across a broad range of habitats for several years showed that an insect functioning both as a pollinator and a floral parasite can be strongly mutualistic in some habitats but commensal or antagonistic in neighbouring habitats. The results for one of the habitats span seven years, demonstrating that the local structure of coevolutionary selection can remain stable across multiple generations. Conservation of the evolutionary processes maintaining long-term biological diversity may require preservation of the conditions that allow a long-term shifting geographic mosaic of coevolutionary hotspots and coldspots.