Hi All, I did not foresee to stir such a discussion, but I am glad I did, and the discussion is very helpful, to show that we are using so many different working definitions. I will give my 2 cents on this.
First of all, we have to distinguish between "Natural Selection" and "Evolution by means of Natural Selection". And in that line, in accordance with Haldane, Lande and Arnold, Futuyma and many more, I think we have to separate the process itself from the result. The result requires heritable variation, the process just needs fitness differences. Combined, we have the process, the result in the next generation and the long-term effect. (I always think about artificial selection, there the result is not part of the actions). Now, the differential reproduction is a comparative definition, you need two groups and compare the reproductive effect. That is a great working definition, but it just does not work in all cases (single inbred population with no genetic variation). A different approach is to look at absolute fitness. If it is larger than 1, in increases in numbers, if it decreases, the species does bad and can go extinct. For me, differential reproduction is insufficient as it fails in obvious cases where nature does select, but does not on the basis of differences between groups, but just because something is maladapted. And differential reproduction is derived from absolute finesses anyway. Anyway, enough food to think about. It is actually funny to read various books about NatSel, and to see how they carefully avoid about actually defining the term. Regards, Kim * Lande R & Arnold SJ (1983) The measurement of selection on correlated characters. Evolution 37:1210-26 * Futuyma DJ (2005) Evolution. Sinauer Associates, Inc., Sunderland, Massachusetts. ISBN 0878931872 * Haldane, JBS (1953) The measurement of natural selection. Proceedings of the 9th International Congress of Genetics. 1: 480-487 -- http://www.kimvdlinde.com
