Warren, If you want succinct, then I believe Endler does the job:
If you have: 1. Phenotypic vaiability that 2. comes from genotypic variability, and that gives 3. Differential reproductive success (due to that phenotypic variability). We call this fitness. Then you will have natural selection, which is just a different genotype frequency in subsequent generation. If that continues in the same way for generations, then we are likely to have Evolution by Natural Selection. These are all necessary and sufficient conditions for natural selection. We can also see that fitness differences CAN come from competition, but they do not HAVE to. And, we must remember that while Darwin coined the term, he knew nothing of genetics, which has come a long way since then. And, there was the New Synthesis that put Darwin's ideas into a more modern framework, with Fischer, White, Mayr. And, then, we have Dawkins and Gould, who might have argued between themselves, but who, by reading, WE can all come to understand evolution better. Cheers, Jim Warren W. Aney wrote: > I've been trying to follow this discussion with little profit until I read > this last posting from Wirt Atmar. This is the most intelligent, succinct, > evocative and accesible (and inspiring) explanation I've ever read on the > topic of basic evolution. Maybe it's old-hat to evolutionary biologists, > but it's going to be part of this wildlife ecologist's permanent lexicon. > > Thanks, Wirt, for persisting on this topic. > > Warren Aney > Senior Wildlife Ecologist > Tigard, OR > > -----Original Message----- > From: Ecological Society of America: grants, jobs, news > [mailto:[EMAIL PROTECTED] Behalf Of Wirt Atmar > Sent: Tuesday, 18 July, 2006 14:20 > To: ECOLOG-L@LISTSERV.UMD.EDU > Subject: Re: Maldaptation, Extinction and Natural selection > > > Dan writes: > > >> I am not an expert on evolution (far from it) but I have a >> hunch that relates to Hutchinson's quote and analogy about >> "the evolutionary play in the ecological theater". >> > > Let me say that you can do no wrong by reading and memorizing G. Evelyn > Hutchinson, and especially his student, Robert MacArthur. > > The metaphor I tend to use however invokes a different art form, that of a > movie. The study of ecology, which entails investigations into the totality > of > the biotic interactions we find on earth, is like the last, current frame of > a > movie that has been running at 24 frames per second for the last several > hundred years. > > When we do ecology, we're looking only at the last frame of the movie. > Ecology is evolution in "now" time, captured in the current frame, but no > matter how > intricately we tease apart the ecological physics of those interactions in > this last frame, the interactions will never make complete sense unless they > are > examined over the course of the entire movie. > > The "ghosts of competitions past," where pronghorn antelope run at high > speed > from a cheetah that's no longer present on the North American plains, is as > good an example as we have of the necessity of imposing time into our > studies, > making Hutchinson's "the evolutionary play in the ecological theater" phrase > all the more relevant. > > Why are developing these metaphors important? On one hand, saying all of > this > is obvious. On the other, these discussions have almost no practical value > when you're in the field, taking detailed measurements. But "science" > doesn't > mean "data." The mathematician Henri Poincare wrote, "Science is built of > facts > the way a house is built of bricks, but an accumulation of facts is no more > science than a pile of bricks is a house." > > "Science" literally means "understanding," and without developing these > perspectives, we really don't understand much of anything. Evolving truly > accurate > mental metaphors and models is fundamental to doing science, of any stripe. > > Saying this, what then of the idea of the "evolutionary algorithm"? In that > regard, you write: > > >> My hunch combined with your analogy below of "evolution as >> algorithm" might be considered "ecology as operating system". >> This focuses on ecology at the ecosystem and biosphere level. >> Your description of the algorithm seems to explain and >> characterize selection well, but it does not seem to account >> for 1) generation of novelty, other than via random or >> error-related mutation, 2) feedbacks that result when the >> organisms and communities/ecosystems alter the environment >> and then have to adapt to their own alterations (as studied >> in "niche construction" and "ecosystem engineers") and >> 3) the infrastructure and maintenance of elements, energy, >> materials that make the instantiation or materialization of >> new forms ("actors") possible, participates in juxtaposing >> them in new "plays" and "cleans up the mess" after the "play" >> (i.e. decomposition and recycling) so that the "theater" is >> not cluttered from past performances. I could convert these >> to algorithm or application/program vs operating system >> examples relation to hardware realizations, memory and/or >> disk space/clutter. >> >> Algorithms are great, but for them to work one needs an >> operating system that can continue to "run" and allow many >> "programs" to "run" and that is robust and does not itself >> "crash". There is also work by folks following up on Robert >> Rosen that suggests that much of the essence of life process >> is non-computable, not algorithmic and non-mechanistic. Some >> of the work here focuses on ambiguity and circularity, both >> of which algorithms do not handle well but life seems >> accustomed to. >> > > I previously wrote the evolutionary algorithm as: > > "Given self-reproduction, Darwinian evolution is composed of only these five > components: > > o a bounded arena > o a replicating population which must eventually expand beyond the > bounds of the arena > o thermodynamically inescapable replicative error, guaranteeing > variation within the reproducing population > o competition for space in that arena among the inevitable variants > o the consequential competitive exclusion of the lesser fit" > > But it's important to note that Darwin probably would have said the same > thing, if the word "algorithm" had been in use 150 years ago. What he did > write, > in the final paragraph of his last chapter in "The Origin of Species," was > this: > > "It is interesting to contemplate an entangled bank, clothed with many > plants of many kinds, with birds singing on the bushes, with various insects > flitting about, and with worms crawling through the damp earth, and to > reflect > that these elaborately constructed forms, so different from each other, and > dependent on each other in so complex a manner, have all been produced by > laws > acting around us. These laws, taken in the largest sense, being Growth with > Reproduction; inheritance which is almost implied by reproduction; > Variability > from the indirect and direct action of the external conditions of life, and > from > use and disuse; a Ratio of Increase so high as to lead to a Struggle for > Life, > and as a consequence to Natural Selection, entailing Divergence of Character > and the Extinction of less-improved forms. Thus, from the war of nature, > from > famine and death, the most exalted object which we are capable of > conceiving, > namely, the production of the higher animals, directly follows. There is > grandeur in this view of life, with its several powers, having been > originally > breathed into a few forms or into one; and that, whilst this planet has gone > cycling on according to the fixed law of gravity, from so simple a beginning > endless forms most beautiful and most wonderful have been, and are being, > evolved." > > This is one of the most quoted paragraphs in all of biology, but the feeling > I get when I see it repeated is that most people are using it merely as a > poetic description of his ideas. I don't believe Darwin meant it to be taken > that > way. > > If you're going to read Darwin, you must first understand that beyond his > being a superior observationist, he was a hard-nosed mechanist, as much as > any > physicist or engineer. He wanted to understand process and mechanism, and in > doing so, gave evolutionary theory for the very first time a very clearly > defined > physics. > > I've written before here that we're not doing ourselves any favors by saying > that "ecology has no laws." More than that, I believe the sentiment to be > nonsense. When I look at nature, I see nothing but rules, where Darwin's > physics > merges seamlessly into the ecological physics of competitive exclusions, > carrying capacities, faunal relaxations and the like. > > If Darwin lived today, in a modern world of bullet-pointed PowerPoint > slides, > his last paragraph would probably look like this: > > o Growth and Reproduction, and by consequence, Inheritance > o Variability in form > o Ratio of Increase leading to a Struggle for Existence > o Natural Selection as a consequence > o Leading to Divergence of Character > o And the Extinction of less-improved forms > > This is the Darwinian algorithm, as explicitly outlined by Darwin himself. > > If this is truly an algorithm, who or what then is doing the processing? > Nature, of course. Given self-reproducing entities, the Darwinian algorithm > is the > inescapable consequence of reproduction in a positively entropic, bounded > universe. > > Finally, as long as we're on this paragraph, let me speak to one other, > unrelated item, one that deals with Darwin's phrase, "There is a grandeur in > this > view of life," a sentence which is also often quoted. > > My own idiosyncratic reading of these last few sentences is that he was > speaking primarily to himself, trying to salve his conscience for the > physics he > was proposing, a physics built on death, disease, famine, pestilence and > predation. To do that, he wrote an extremely uncomfortable truth: "Thus, > from the war > of nature, from famine and death, the most exalted object which we are > capable of conceiving, namely, the production of the higher animals, > directly > follows." > > I personally feel the same way. In any universe that I would build, there > would be no death, no aging, no sickness or war. The only rub is that I have > no > idea how such a world could either come into being or how it could be > maintained. In Darwin's alternate universe of death and famine, we > unfortunately have a > simple, easy-to-understand mechanism, one that does eventually builds the > most exalted objects which we are capable of conceiving, the production of > the > higher animals. > > Wirt Atmar > > -- ------------------------------------- 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://zoo.bio.ufpr.br/zoologia/ Ecologia e Conservação na UFPR http://www.bio.ufpr.br/ecologia/ ------------------------------------- http://jjroper.sites.uol.com.br
