interest in extinction, yet research on the topic is still at a reconnaissance level, and our present understanding of its role in evolution is weak. Despite uncertainties, extinction probably contains three important elements. (i) For geographically widespread species, extinction is likely only if the killing stress is one so rare as to be beyond the experience of the species, and thus outside the reach of natural selection. (ii) The largest mass extinctions produce major restructuring of the biosphere wherein some successful groups are eliminated, allowing previously minor groups to expand and diversify. (iii) Except for a few cases, there is little evidence that extinction is selective in the positive sense argued by Darwin. It has generally been impossible to predict, before the fact, which species will be victims of an extinction event.

I thank David Jablonski for many helpful discussions and for his helpful comments on the manuscript. This research was supported by National Aeronautics and Space Administration Grants NAGW-1508 and NAGW-1527.

References

Alvarez, L. W., Alvarez, W., Asaro, F. & Michel, H. V. (1980) Extraterrestrial cause for the Cretaceous-Tertiary extinction. Science 205, 1095–1108.


Clarke, A. (1993) Temperature and extinction in the sea: a physiologist's view. Paleobiology 19, 499–518.

Clemens, W. A. (1986) Evolution of the vertebrate fauna during the Cretaceous-Tertiary transition, in Dynamics of Extinction, ed. Elliot, D. K. (Wiley-Interscience, New York), pp. 63–85.

Copper, P. (1988) Ecological succession in Phanerozoic reef ecosystemns: Is it real? Palaios 3, 136–152.


Darwin, C. (1859) On the Origin of Species (Murray, London).

Dodson, P. (1990) Counting dinosaurs: How many kinds were there? Proc. Natl. Acad. Sci. USA 87, 7608–7612.


Jablonski, D. (1986a) Causes and consequences of mass extinctions: a comparative approach, in Dynamics of Extinction, ed. Elliot, D. K. (Wiley-Interscience, New York), pp. 183–229.

Jablonski, D. (1986b) Mass and background extinctions: the alternation of macroevolutionary regimens. Science 231, 129–133.

Jablonski, D. (1991) Extinctions: a paleontological perspective. Science 253, 754–757.


LaBarbera, M. (1986) The evolution and ecology of body size, in Patterns and Processes in the History of Life, eds. Raup, D. M. & Jablonski, D. (Springer-Verlag, Berlin), pp. 69–98.

Levinton, J. S. et al. (1986) Organismic evolution: the interaction of microevolutionary and macroevolutionary processes, in Patterns and Processes in the History of Life, eds. Raup, D. M. & Jablonski, D. (Springer-Verlag, Berlin), pp. 167–182. [other authors: Bandel, K., Charlesworth, B., Muller, G., Nagl, W., Runnegar, B., Selander, R. K., Stearns, S. C., Turner, J. R. G., Urbanek, A. J. & Valentine, J. W.]

Lyell, C. (1833) Principles of Geology (Murray, London), Vol. 3.



The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement