Talk:Population bottleneck

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From the article:

All species being survivors in relation to the levels their environment support, there is reasonable thinking that says human beings are due for another bottleneck sometime soon.

Really? Please provide cites that this thinking is mainstream.

World population is rising rapidly. Each year there are far more births than the previous year. That situation is almost certain to continue for decades. Alfred Kinsey (talk) 22:05, 4 June 2009 (UTC)[reply]

List of species

It seems like we could benefit from a separate article listing known species which have experienced a genetic bottleneck, eg. CA Condor, Blue Whales.

AIDS

Also, AIDS, whilst a disastrous pandemic, is not anywhere near the level needed for a bottleneck.

Not globally, but it is approaching (and projected to reach) that level in parts of Africa. (The Black Death was only a regional phenomenon, too.) Mkweise

AIDS is not at, nor projected to be anywhere near, the scale of the Black Death. Sub-Saharan Africans have very high birthrates, preventing a bottleneck. Alfred Kinsey (talk) 22:01, 4 June 2009 (UTC)[reply]

Bunch to bushel

"From a bunch to a bushel" sounds poetic, but I think will lose some readers (even some fluent in English) -- can someone find a better way to say this? Slrubenstein

I think a loss of at least 50% qualifies, but I'm not sure. If anyone knows better, please fix the article. Mkweise 01:23 23 May 2003 (UTC)

YPB

What is "ybp"? Uncommon abbreviations should either be spelled out in full the first time they are used in an article, or they should be linked to a glossary entry.

"Years before present" should be spelled out in full at the first encounter.--Wetman 12:52, 12 Mar 2005 (UTC)

Drift

"as the rate of drift is inversely proportional to the population size." No, the rate of drift is a constant. This needs rethinking as well as rephrasing. --Wetman 12:52, 12 Mar 2005 (UTC)

The rate of mutation may be constant; but the rate of genetic drift, ie the changes in the proportions of alleles in a population, does indeed become greater, the smaller the population size. -- Jheald 11:47, 9 February 2006 (UTC).[reply]

Put more simply, the changes in general population characteristics will be more rapid in a small population than in a large one. However, inverse proportionality is both unlikely and unprovable. The graph line is more likely to be somewhat hyperbolic.Logical Analyst (talk) 20:02, 26 December 2009 (UTC)[reply]

Wisent or Bison?

Is the table in Example in the animal world section about wisent (European bison) or about American bison? The first row cites "Before 1492", so apparently it refers to the American Bison (arrival of Europeans is always considered a key point in American history); the second one cites 750 living bisons in 1890, and this could refer to both the European and American Bison; the third row clearly reports the number of European Bison (as told in American Bison there are thousand of living bison now). I'm going to assume that the table is about American Bison and fix consequently, if no one answer. GhePeU 21:37, 14 September 2005 (UTC)[reply]

I couldn't find a confirmation on the wisent having only 2 different versions of the Y-chromosomes, and I thought if it was so that the paper I read on genetic variation in the Wisent (Luerner et al., 2005) would have mentioned it. However, if you have a source that says there are 2 Y versions, please put it back in! and cite your source. Satyrium 15:37, 9 September 2006 (UTC)[reply]

Near-Extinction evolution theory

Near-Extinction evolution theory was recently created. If there is anything there worth keeping it should be merged here. Zeimusu | Talk page 13:18, 26 December 2005 (UTC)[reply]

No. I don't see anything of value in that article, so I'd rather not merge it here. It seems a bit of puffery. As to whether or not it should be deleted, I'll let others decide. Ted 03:26, 21 April 2006 (UTC)[reply]

No. I'm in full agreement with TedE. Near-extinction seems very, very hypothetical, and doesn't add anything new and well-supported. Satyrium 15:04, 9 September 2006 (UTC)[reply]

Since there was nothing to merge from the article (I concur with the above), and there weren't even any sources to move over, I've redirected that article here. -Harmil 07:45, 6 October 2006 (UTC)[reply]

DNA coalescence

As far as I know, DNA are expected to coalesce, even if there is no population bottleneck. So I changed that part (on Humans). That section would benefit from some outside sources. Krubo 13:32, 29 May 2006 (UTC)[reply]

I tried to improved it. How does it look now? Fred Hsu 01:37, 17 March 2007 (UTC)[reply]

Toba Catastrophe and coalescence

Re the discussion post above on human coalescence:

I think the section of the main article labeled "Humans" is now internally contradictory. It begins by saying that coalescence 70K years ago is to be expected and doesn't indicate a bottleneck. Then, the next two paragraphs discuss two theories as to why a bottleneck occurred.

Can somebody explain this apparent contradiction, or is the section actually cohesive, and I'm just not getting it?

If a contradiction does exist, I think the article should be edited to explain that coalescence is a matter of some controversy. --Tannerpittman 16:57, 15 February 2007 (UTC)[reply]

Please check the section again to see if the new wordings now clearly state these two contradictory views. Fred Hsu 01:40, 17 March 2007 (UTC)[reply]

Calculation of time of bottleneck events

Can someone add a note or link about how bottleneck times are calculated? I presume that it's done by measurements of genetic variation compared to the background rate of genetic drift (complicated by differences in local sources of mutagenic events and variations in species ability to resist mutations, both mentioned in Deinococcus radiodurans). --Scott McNay 23:18, 16 March 2007 (UTC)[reply]

External bottleneck

User:MichaelCPrice made the following change indicating that genetic evidences do not contradct the Toba catastrophe theory because genetic evidences only disprove the existence of of "external bottleneck". What is an external bottleneck? Can someone provide some references? I am restoring the original version until more references are presented. Fred Hsu 14:33, 4 April 2007 (UTC)[reply]

Please see the inline reference to The Ancestor's Tale in the previous paragraph. Based on numerous lineages of different genes, it has been determined that there were no population bottleneck. By bottleneck, researchers mean what is meant by population bottleneck, not a single breeding pair (probably what was meant by "external bottleneck"). Fred Hsu 15:09, 4 April 2007 (UTC)[reply]

I wrote extremal , not external :-) And yes, I meant by this a single breeding pair. A population bottleneck the hypothectical size produced by Toba (1,000-10,000?) would contain many lineages; hence convergence of gene lines (Y, mt or nuclear) is not mandatory, and hence does not conflict with the genetic evidence. --Michael C. Price ^talk 15:34, 4 April 2007 (UTC)[reply]

I stand corrected. "Extremal". I'll read more carefully next time. I will go back to re-read these references to make sure. But my understanding is that most researchers do not believe in a human population bottleneck, when all genes are taken into account. Even though we are not talking about a single breeding pair, 1,000-10,000 is still a small population, and this should leave a definite signature on shape of the gene lineages, when the genome is considered as a whole. But no such evidence has been presented. Fred Hsu 15:48, 4 April 2007 (UTC)[reply]

Yes, bottleneck sizes can be inferred by the amount of exant variation, but it is certainly not true that more ancient genetic colascence times (such as mt-Eve at ~150kya) disprove the existence of more recent bottlenecks (such as Toba at 75kya).

Perhaps these paragraphs on various articles should be revised to talk about the shape of gene lineages as a whole, instead of just mentioning the discrepancies between mtDNA and Y-chromosome. Looking at just a few genes (e.g. mt, Y or a few nuclear genes) does not prove nor disprove bottleneck. It is the whole picture which is at odds with Toba catastrophe theory. Fred Hsu 16:05, 4 April 2007 (UTC)[reply]

Perhaps it is, I don't know, but the statements about mt-Eve etc were incorrect and I have modified/reverted them.--Michael C. Price ^talk 16:43, 4 April 2007 (UTC)[reply]

Notice that the Ancestor's Tale reference is in opposition to the bottleneck. I've rearrange the pargraphs to make that more clear. Fred Hsu 17:10, 4 April 2007 (UTC)[reply]

No, Dawkins' The Ancestor's Tale explicitly supports the volcanic bottleneck of c 70,000 ya. See the The Grasshopper's Tale, p416. I shall amend the article accordingly. --Michael C. Price ^talk 11:49, 21 May 2007 (UTC)[reply]

It's a books.google and while a search turned up bottleneck it did not turn up Toba. FYI CarolMooreDC (talk) 16:47, 18 May 2009 (UTC)[reply]

Which primate?

In the third paragraph of the "examples in animal world" section a mention is made of evdience that a certain primate species has suffered such a bottleneck. It seems like the species name should be given(along with a wikilink if there is a corresponding article) and maybe a citation. I know nothing about this myself so does anyone else know what this refers to? -Joshua Davis 01:20, 16 April 2007 (UTC)[reply]

Anti-Malthus

This article does not explain the premises, symptoms, causes and effects of a population bottleneck in a species. Is it a heuristic theory? Is sounds anti-Malthusian anyway. Anwar (talk) 09:47, 27 May 2008 (UTC)[reply]

Human bottleneck

A bottleneck in the Northern European population (not globally) seems pretty well established by now. One reference is here: "Genetic variability in a genomic region with long-range linkage disequilibrium reveals traces of a bottleneck in the history of the European population" by Claudia Schmegner1, Josef Hoegel1, Walther Vogel1 and Günter Assum1. http://www.springerlink.com/(p3nnrw55on33n5nobeur1533)/app/home/contribution.asp?backto=issue,14,19;journal,10,510;linkingpublicationresults,1:100421,1 but someone should really do some more research on the other articles referenced before modifying the main page.

Moved this thread here, no comment on it's anonymous and undated initial content or the related ones above. However the fact of a population bottleneck that produced the lack of genetic diversity in the surviving human species relative to the other great apes is well established. What is still controversial are the details, less so about when it occurred because this can be established by examination of the genome and more so about where and why. Either the section should be rewritten to show this or a new article created. Lycurgus (talk) 14:52, 22 November 2009 (UTC)[reply]

Also, with the possible exception of some religious actors, nobody thinks there was a single breeding pair. The estimates I've seen range from a little under a thousand to around 20 thousand. The current text of the section distorts the established scientific consensus. Lycurgus (talk) 10:28, 23 November 2009 (UTC)[reply]