Taxonomy, phylogeny, and coevolution of pines and their stem rusts

Abstract

We review and reinterpret major events in the evolution of pines and their stem rusts using information from their taxonomy, genetics, biogeography, and fossil history. Understanding of pine evolution has been significantly revised in the last 20 years. Pines appear to have evolved early in the Mesozoic and to have diversified and migrated throughout middle latitudes in the Northern Hemisphere supercontinent, Laurasia, by the end of the Mesozoic. By this time, the major subgenera had appeared (subgenus Strobus, oldest) as well as several early subsections, probably including at least Cembroides, Gerardianae, Strobi, Canarienses, Pineae, Sylvestres, Ponderosae, and Australes. In the early Tertiary, global climates changed and favored the spread throughout middle latitudes of angiosperm floras adapted to hot, humid conditions. These apparently fragmented and displaced pines into local cool dry refugia in polar latitudes, warm dry refugia at low latitudes, and scattered upland refugia at middle latitudes (e.g., present Rocky Mountains and Japan). Several subsections were split north and south. Some of these areas experienced intensive mountain-building. which created environmental heterogeneity that favored pine radiation and created secondary centers of origin (e.g., Mexico). Following the climatic deterioration at the end of the Eocene, tropical-adapted angiosperms were eliminated throughout middle latitudes, and pines replaced them. Radiations of subsections Oocarpae, Sabinianae, and Contortae and of many species within subsections seem to date to this period.

Citation

Millar, C. I.; Kinloch, B. B. 1991. Taxonomy, phylogeny, and coevolution of pines and their stem rusts. In: Y. Hiratsuka, J. K. Samoil, P. V. Blenis, P. E. Crane, and B. L. Laishley, editors. 1991. Rusts of Pine. Proc. 3rd IUFRO Rusts of Pine Working Party Conference, Sept. 18-22. 1989, Banff, Alberta. For. Can, Northwest Reg., North. For. Cent., Edmonton, Alberta. Inf. Rep. NOR-X-317: p. 1-38