Niches are best defined by the species - after all, what each species "does= " is its niche.... Imagine a planet with no animals, but with plants. There are no animal niches...
But, if we want to use the idea of potential for use, in which case we woul= d probably be talking about complexity in some sense, then why not just use the word complexity? After all, if we just use any word as we please, then we have to define our use of that word each time so that others who use the same word in a different way know what we mean - quite cumbersome that. I believe you meant MacArthur's warblers...and, if you read his paper today= , I think you might find a bit of him "proving" what he wanted to see. I could say more, but typing with a cast makes one be brief.... Jim On 11/23/07, William Silvert <[EMAIL PROTECTED]> wrote: > > We ecologists define the niche. We can stick with the Hutchinsonian > definition, or we can modify it in ways we might find more useful. > > Niches, empty or not, are not fixed. If there is a lot of breadth, then > organisms will tend to partition the "hyperspace" among themselves. > > Consider David Lack's warblers, who ended up occupying the same trees but > at > different heights above the ground. I think he identified three species. = I > suspect that if the trees were shorter he might have found just two, and > if > they were taller, more than three. > > The concepts of niche and speciation are complicated and we are still > working on them. To do so effectively, we should try to free ourselves > from > rigid definitions, although of course we always have to be clear what we > mean. The reason I like the term "empty niche" is not that I am against > Hutchinson and his disciples, but because it is a useful concept. If we > reject it, and insist instead on circumlocutions like "potential resource > manifold in hyperspace not currently fully exploited by any species" then > it > interferes with our doing science. > > Bill Silvert > > > ----- Original Message ----- > From: "Warren W. Aney" <[EMAIL PROTECTED]> > To: "William Silvert" <[EMAIL PROTECTED]>; <[email protected]> > Sent: Friday, November 23, 2007 6:18 PM > Subject: RE: "unoccupied" niches and 'competitive exclusion" > > > > Does the species define the niche? Or (in evolutionary terms) does the > > niche > > define the species? David seems to be saying that the species defines > the > > niche and Bill seems to be arguing that the niche exists independent of > > the > > species filling it. Did Darwin's Galapagos finches evolve to fit > > pre-existing niches, or did they define the niche as they evolved? > --=20 James J. Roper, Ph.D. Ecologia e Din=E2micas Populacionais de Vertebrados Terrestres Caixa Postal 19034 81531-990 Curitiba, Paran=E1, Brasil E-mail: [EMAIL PROTECTED] Telefone: 55 41 33857249 Mobile: 55 41 99870543 http://www.bio.ufpr.br/ecologia/ Ecologia e Conserva=E7=E3o na UFPR http://jjroper.googlespages.com Personal Pages
