THE EVOLUTIONARY DIVERSIFICATION OF SEED SIZE: USING THE PAST TO UNDERSTAND THE PRESENT
Article first published online: 6 FEB 2012
© 2012 The Author. Evolution© 2012 The Society for the Study of Evolution.
Volume 66, Issue 5, pages 1636–1649, May 2012
How to Cite
Sims, H. J. (2012), THE EVOLUTIONARY DIVERSIFICATION OF SEED SIZE: USING THE PAST TO UNDERSTAND THE PRESENT. Evolution, 66: 1636–1649. doi: 10.1111/j.1558-5646.2011.01527.x
- Issue published online: 20 APR 2012
- Article first published online: 6 FEB 2012
- Accepted manuscript online: 12 DEC 2011 05:00PM EST
- Received November 24, 2010, Accepted November 16, 2011
Vol. 66, Issue 10, 3311, Article first published online: 6 AUG 2012
- Evolutionary trends;
- plant traits;
- seed size
The Devonian origin of seed plants and subsequent morphological diversification of seeds during the late Paleozoic represents an adaptive radiation into unoccupied ecological niche space. A plant's seed size is correlated with its life-history strategy, growth form, and seed dispersal syndrome. The fossil record indicates that the oldest seed plants had relatively small seeds, but the Mississippian seed size envelope increased significantly with the diversification of larger seeded lineages. Fossil seeds equivalent to the largest extant gymnosperm seeds appeared by the Pennsylvanian, concurrent with morphological diversification of growth forms and dispersal syndromes as well as the clade's radiation into new environments. Wang's Analysis of Skewness indicates that the evolutionary trend of increasing seed size resulted from primarily passive processes in Pennsylvanian seed plants. The distributions of modern angiosperms indicate a more diverse system of active and some passive processes, unbounded by Paleozoic limits; multiple angiosperm lineages independently evolved though the upper and lower bounds. Quantitative measures of preservation suggest that, although our knowledge of Paleozoic seeds is far from complete, the evolutionary trend in seed size is unlikely to be an artifact of taphonomy.