Submitted to: Proceedings of the Royal Society of London B
Publication Type: Peer reviewed journal
Publication Acceptance Date: 4/28/2005
Publication Date: 7/5/2005
Citation: Givnish, T.J., Pires, J.C., Graham, S.W., McPherson, M.A., Prince, L.M., Patterson, T.B., Rai, H.S., Roalson, E.H., Evans, T.M., Hahn, W.J., Millam, K.C., Meerow, A.W., Molvray, M., Kores, P.J., O'Brien, H.E., Hall, J.C., Kress, W.J., Sytsma, K.J. 2005. Repeated evolution of net venation and fleshy fruits among monocots in shaded habitats confirms a priori predictions: evidence from an ndhf phylogeny. Proceedings of the Royal Society of London B. 272(1571):1481-1490. Interpretive Summary: Sequence variation in the chloroplast gene ndhF was used to estimate relationships across the monocotyledons, based on 282 taxa representing 74 of 92 monocot families and all 12 monocot orders. The resulting phylogeny is highly resolved and supports the common ancestry for all groups recognized by studies with other genes. We also show that that net venation and fleshy fruits have evolved upon invasion of shaded habitats, and reverted to parallel venation and dry, passively dispersed fruits upon invasion of open, sunny habitats. In fact, net venation has arisen at least 26 times in monocots and been lost 8 times, while fleshy fruits have arisen 22 times and been lost 11 times. Both traits arose together at least 15 times and been lost together five times.
Technical Abstract: We present a well-resolved, highly inclusive phylogeny for monocots based on ndhF sequence variation, and use it to test the hypotheses that net venation and fleshy fruits have undergone concerted convergence and represent independent but often concurrent adaptations to shaded conditions. Our data demonstrate that net venation arose at least 26 times and was lost 8 times over the past 90 million years; fleshy fruits arose at least 22 times and disappeared 11 times. Both traits show a highly significant pattern of concerted convergence (P < 10-9),arising 15 times and disappearing 5 times in tandem. This phenomenon appears driven by even stronger tendencies for both traits to evolve in shade and be lost in open habitats (P < 10-10 to 10-23). These patterns are among the strongest ever demonstrated for evolutionary convergence in individual traits and the repeatability of evolution, and the strongest evidence yet uncovered for concerted convergence.