Talk:Unified neutral theory of biodiversity

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  1. with probability 1 − m, pick two individuals at random from the local community. If they belong to the same species, no action is taken. Otherwise, with equal probability, replace one of the individuals with the offspring of the other. In other words, the two individuals serve as candidates for death and parentood.
  2. with probability m, pick one individual at random from the local community. Replace it by a new individual chosen with a probability proportional to the abundance of the species in the metacommunity. This corresponds to the death of the chosen individual in the local community followd by the arrival of an immigrant from the metacommunity.

Stochastic modelling of species abundances under the UNTB[edit]

  1. What is meant by "It is always possible to rescale so that &m1=1."? Also, the symbol isn't displayed correctly (missing ';') This line stands just above the Example in the section. Eef (A) 11:22, 24 Jun 2004 (UTC)

Hi Eef

Thanks for your interest.

The line should read mu=1. One can always rescale the time increment so that this is correct. I'll change the article accordingly.

best wishes

Robinh 12:53, 24 Jun 2004 (UTC)

I am currently preparing a talk on the UNTB and have read the relevant papers [Hubbell 2001 (of course)], [Vallade,Houchmandzadeh 2003 [1]], [Volkov, Hubbell 2003 [2]] and [Etienne 2005 [3]] describing the urn processes in the metacommunity and the local community. I think this distinction is not made clear in this section. In fact, the transition probabilities given are those in a completely isolated community with absorbing states of single species dominance. This is a notice, that I have decided to completely rewrite this section. --Ralf 07 Feb 2007

Yup, this isn't made clear. My own research is in the isolated case, so that's what I focussed on when I wrote it. The isolated case is, as you point out, simpler. Good luck with the rewrite! Robinh 16:03, 7 February 2007 (UTC)

Contradicting Darwinism[edit]

Does it really? I didn't read it to contradict "survival of the fittest", did I miss that bit? Guettarda 23:48, 16 Dec 2004 (UTC)

Hi. I didn't edit that bit of the article, so I can't be sure what the author intended, but the UNTB does specifically contradict "survival of the fittest" but none of Darwin's theories. I nearly reverted the edit until I actually read survival of the fittest!

best wishes Robinh 08:35, 17 Dec 2004 (UTC)

Actually I posted that question while I thought the author was still editing, and was hoping they would explain what they meant. But I should have read the link. I wonder if it makes sense to leave since it seems to reduce the clarity of the article...on the other hand, if you read the link it hits home the idea that the UNTB goes against the idea of competition structuring communities. Of course my take when I read the book (which was about 2 years ago) was that Hubbell backed away from saying that competition did not play a role (since there was an uptick in the 7 most abundant species), but rather, that a neutral model could explain much of the behaviour of the system. Of course my memory might be putting my own thoughts onto Hubbell's words. Guettarda 13:47, 17 Dec 2004 (UTC)

Hello Guettarda

I think you put your finger on the nail when you say that "a neutral model could explain much of the behaviour of the system". If true, this doesn't mean that competition has zero effect, just zero measurable effect on species abundance curves. My take on it is that any species with a genuine Darwinian disadvantage would have disappeared a long time ago. Still, I think the edit should stand: I for one found it very apposite (and indeed informative). I would says that the UNTB is so humoungously nonintuitive precisely because a cursory understanding of it appears to be at odds with a cursory understanding of Darwin. Of course there is no real contradiction: the contradiction is between UNTB and survival of the fittest. I think the edit goes a long way towards clarifying this issue (which isn't to say that it couldn't be improved still further!)

best wishes Robinh 14:00, 17 Dec 2004 (UTC)

Page title[edit]

An anon did a cut and paste move to Unified Neutral Theory of Biodiversity and Biogeography via Unified neutral theory of biodiversity and biogeography, which I've reverted to preserve the history. I've no opinion on the page title myself, but if it should be moved it'll need to be done by an admin (or via WP:RM). sjorford:// 21:54, 28 Jan 2005 (UTC)

Niche construction = niche assembly?[edit]

I assumed these were equivalent in my most recent edit prior to this post. - Samsara 01:27, 3 January 2006 (UTC)

I Can talk Filefire 12:35, 9 January 2007 (UTC)

Hubbell article[edit]

I've started a Stephen P. Hubbell article. Some of you who are familiar with Professor Hubbell may wish to edit/contribute. I'm a layman; I can hardly spell UNTB. Thanks. — Muffuletta 00:43, 28 February 2006 (UTC)

Relevance of R programming language?[edit]

The R programming language can be used to show that the maximum likelihood estimate for θ is about 1.1478.

I would suggest replacing "the R programming language" with something more general like "numerical methods," unless there's some reason why the language is important. Surely you are just maximizing a function, which can be done by any number of methods... such as "a graphite pencil and a sheet of recycled paper"? Mtford 09:51, 29 January 2007 (UTC)

Hi Mtford. When I wrote this I had just completed a suite of R software that computed θ. I have a paper that discusses the method under review at Journal of Statistical Software right now, so I'll rephrase the article now, and put a citation in when (if?) it gets accepted. Best wishes, Robinh 08:07, 30 January 2007 (UTC)


"The Unified Theory makes a large number of falsifiable hypotheses."

"The Unified Theory also makes predictions that have profound implications for the management of biodiversity, especially the management of rare species."


And one more funny thing: the list of "notable proponents" includes only the author himself. Come on...

Llnoba 17:58, 2 February 2007 (UTC)

Please be specific about what you consider non-neutral about this article. Guettarda 18:14, 2 February 2007 (UTC)

Is this an attempt at a bad joke? I find the entire article to be non-neutral. It makes sweeping assertions about the usefulness and importance of the theory and claims about its fit to empirical data without citing references to these assertions. It also does not discuss criticism of the theory. As a separate criticism, much of the article is overly technical. Cazort 19:52, 5 November 2007 (UTC)

I'd like to suggest that the notable proponents and critics section of the article be deleted. It adds nothing to the article. Theinsomniac4life (talk) 12:26, 16 July 2010 (UTC)

I disagree, it is a theory so knowing who supports it and who opposes it is quite significant. As ways of improving the article go, that doesn't seem like one to me. Smartse (talk) 13:18, 16 July 2010 (UTC)
Except few of the listed people are significant enough to merit their own pages, so mentioning them seems irrelevant. Further, appeal to authority is not a characteristic of encyclopedia articles. Again, it adds nothing to the article, and actually makes it worse, seem like trivial publicity for a few vocal names in the field.Theinsomniac4life (talk) 02:09, 18 July 2010 (UTC)

Broken-Stick Model is neutral?[edit]

I'm not sure about it, but I believe the Broken-Stick model is not purely neutral, given it assumes each species occupies some niche breadth, and only the niche breath is random and independent between species. leonardorejorge —Preceding comment was added at 18:21, 25 October 2007 (UTC)

Relation to other theories[edit]

I introduced a few improvements in the description of the relationship between the UNTBB and other theories. I hope the previous editors of the article will agree: (1) Since MacArthur’s broken stick is indeed a niche assembly theory, I moved the comment about the broken stick where niche assembly theories are mentioned (I think this solves leonardorejorge’s point). I also added the corresponding reference. (2) I replaced the assertion that MacArthur & Wilson Island Biogeography is a neutral theory by the assertion that Hubbell considers that it is a neutral theory. (3) I clarified that neutral theories are dispersal assembly theories (while, in the previous version, dispersal assembly theories were presented as alternatives to the neutral theory). (4) I replaced “niche construction” by “niche assembly”. “Niche assembly” theories assume that different species hold different niches instead of being ecologically equivalent, as the neutral theory assumes. “Niche construction” (as defined in another article in Wikipedia) refers to how the effects of species in their environment can modify niche structure, which is related but different from niche assembly (this answers Samsara’s question). (5) I mention an alternative to the neutral theory which has been just published in Ecology Letters. (6) I removed “Other examples of non-neutral explanations would be to hold that older organisms are fitter in the Darwinian sense”. As I understand it, changes in fitness through individual development do not contradict neutrality if they hold for all individuals regardless of species.Rupira 19:43, 12 November 2007 (UTC)

Hi Rupira. I reckon most of your edits are good. Could you cite the Ecology Letters paper (I don't have access to a library right now)?. And I'm not sure about your number 6. The older organisms being fitter was a reference to non unified neutral theory, as then the per-capita equivalence is lost. I'll put that back in if I find somewhere suitable for it. Best wishes, Robinh 22:14, 12 November 2007 (UTC)
Thanks, Robinh. I added the reference to the Ecology Letters paper (by the way, you can read it without a library, because this one is open access), and also some more details in the other references. About point 6, I would say that there is still per capita equivalence if we consider the whole life cycle, that species abundances will still be determined by ecological drift (plus migration and speciation), and that the results of the unified neutral theory should equally apply. However, if you know of some reference clarifying this point, that would be interesting. Best, Rupira 10:31, 13 November 2007 (UTC)
Hi again Rupira. I see what you mean about point 6: the entire life-cycle could well be the central concept. You are right that there is an ambiguity about what exactly "per capita equivalence" means. I always took it to mean that all sites are occupied by organisms that are equivalent to one another at each timestep; but you interpret it as meaning that any two organisms in the system are equivalent (this interpretation allowing older organisms to produce more seeds, for example, which would be forbidden in the first interpretation). These are different! Hmmm. I wonder which one Hubbell meant. Best wishes, Robinh 22:23, 13 November 2007 (UTC)

Dynamics under neutral hypothesis[edit]

First off, citation [7] in the text points to the correct article. However, the article in the reference list at the end is not concerned with the species turnover distribution. Secondly, while the theory in that article is certainly neutral, it has not much to do with the somewhat boastfully named Unifying Neutral Theory of Biodiversity, which this article is about. In fact, the authors propose the gamma distribution for species abundances which arises from a simple linear model without any species interaction (i.e. limits on the community size) whatsoever. And finally the variable r in the equation for P(r,t) is called gamma in the right hand side. I am inclined to delete the section. And while I am at it, I might remove the ham-fisted examples throughout the text, as well. (talk) 03:42, 24 January 2012 (UTC)

Thanks for your comments. Be bold! Robinh (talk) 08:12, 24 January 2012 (UTC)

A tip for an addition to the "Testing the theory" section[edit]

Here is a lead for an addition that I don't have time to write-up, but which on of the article's authors may take an interest in. A new paper is out showing how the theory breaks down for marine ecosystems (Connolly et al. 2014: "Commonness and rarity in the marine biosphere"), and is a free download at PNAS. Science Daily also has an article about the paper. Coastwise (talk) 06:47, 2 June 2014 (UTC)