that favor niche shifts in the resident species [cf. Ackerly (2003)]. Then again, such changes would be counterbalanced by probable reductions in genetic diversity and human species introductions.

If attention is focused on ecological traits that are highly labile, and likely to evolve quite rapidly, optimism about in situ adjustments may well be warranted. My basic argument is that it is important to appreciate that some ecological traits are far less likely to evolve rapidly, and that this conservatism has consequences. As we proceed to predict responses to global change, I believe it will be necessary to acknowledge and more finely characterize the spectrum that exists in the evolutionary lability of ecologically relevant traits. Ironically, however, we are rapidly creating genuinely unparalleled circumstances in which it is becoming difficult to apply our expanding knowledge of the past to predict the future. In this very important sense, it is becoming increasingly unclear what lies ahead for biodiversity.

I thank F. Ayala, J. Avise, and S. Hubbell for inviting me to participate in the colloquium and for their patience; my laboratory group at Yale, where many of these ideas have been vetted, and especially D. Ackerly, E. Edwards, R. Ricklefs, C. Webb, and, J. Wiens, who, over the years, have shaped the outlook developed there; C. Bell, J. Cavender-Bares, P. Crane, C. Davis, T. Feild, L. Lohmann, T. Near, and D. Tank for helpful discussions; B. Moore for an insightful critique of the manuscript; and members of the Scientific Committee of the bioGENESIS program within DIVERSITAS. My work on angiosperm phylogeny and biogeography has been supported recently by the National Science Foundation through two Assembling the Tree of Life grants, Cyberinfrastructure for Phylogenetic Research, and the National Evolutionary Synthesis Center Northern Hemisphere Phytogeography Working Group.