> It seems to me a bit arbitrary to accept that natural selection is > taking place when a certain fraction of individuals are selectively > culled from a population, yet when that fraction reaches 100% that > something different is necessarily going on. To be sure, the RESPONSE > of a population to natural selection when mortality is 100% will be a > moot point (unless one is considering selection of higher scale > entities, dare I say groups?), but to deny that the same processes are > at work seems like a bid for special treatment. Indivdiuals are not selectively "culled" from a population, but rather they leave fewer descendants than others.
I would say that a population decline is probably completely independent of natural selection, in that something else is causing the decline. Natural selection is only about the differential representation of genes in subsequent generations, in which some individuals with some traits leave more descendents - WHEN natural selection is occuring. So, my point has nothing to do with how many individuals are involved. Besides, natural selection works with individuals, not populations... Cheers, JIm -- ------------------------------------- James J. Roper, Ph.D. Universidade Federal do Paraná Depto. de Zoologia Caixa Postal 19020 81531-990 Curitiba, Paraná, Brasil ===================================== E-mail: [EMAIL PROTECTED] Phone/Fone/Teléfono: 55 41 33611764 celular: 55 41 99870543 e-fax: 1-206-202-0173 (in the USA) ===================================== Zoologia na UFPR http://www.bio.ufpr.br/zoologia/ Ecologia e Conservação na UFPR http://www.bio.ufpr.br/ecologia/ ------------------------------------- http://jjroper.sites.uol.com.br
