Talk:Population bottleneck

message: :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)
thread_title:  From the article: 

message: 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)
thread_title:  AIDS 

message: 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)
thread_title:  YPB 

message: "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)
replies: text: 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)
thread_title:  Drift 

message: 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)
replies: text: 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)
thread_title: Wisent or Bison?

message: 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)
replies: text: 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)

text: 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)
thread_title: Near-Extinction evolution theory

message: 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)
thread_title: DNA coalescence

message: 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)
thread_title:  Toba Catastrophe and coalescence 

message: 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)
thread_title:  Calculation of time of bottleneck events 

message: 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)
thread_title: Which primate?

message: 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)
thread_title:  Anti-Malthus 

message: 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)
replies: text: 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)
thread_title:  Human bottleneck 

message: The lead contains the following sentence: These new selective pressures may have acted on genetic variation that has already drifted out of the population. I think it says that at a certain past time selection may have acted on gene alleles that weren't there, because they had drifted to extinction. But selection cannot work on non-existing alleles. I think the intention was to say that some alleles that have been in the population but are no longer here because of drift would have been positively selected on by the present environment if it wasn't for the fact that they are gone. --Ettrig (talk) 07:16, 17 February 2011 (UTC)
replies: text: I have left a message on the student's talk page welcoming them to the world of peer review!--JimmyButler (talk) 15:52, 17 February 2011 (UTC)

text: Thanks for your input! That is what I meant when I said that; sorry if my wording was a bit confusing. I will change the sentence now. I'll probably use your words, so I hope that is okay.--Rebekah best (talk) 22:51, 17 February 2011 (UTC)
replies: text: By the way, thanks for letting me fix it myself. I get points for keeping track of my edits.--Rebekah best (talk) 23:01, 17 February 2011 (UTC)
thread_title:  Selection on non-existing genes? 

message: This article says: Population bottlenecks reduce the genetic variation and thereby also the population's ability to adapt to new selective pressures. This contrasts with punctuated equilibrium that says: 
Smaller populations on the other hand, which are isolated from the parental stock, are decoupled from the homogenizing effects of gene flow. In addition, pressure from natural selection is especially intense, as peripheral isolated populations exist at the outer edges of ecological tolerance. One says little adaptation in small populations, the other says more adaptation in smaller populations. Is there a real conflict here? Can the differences be clarified? --Ettrig (talk) 06:06, 18 February 2011 (UTC)
thread_title: Little adaptation in small populations?

message: Can anything be found/included about what happens when a bottleneck occurs such that the remaining population will go extinct?  Like is there even such a thing as a critical mass or something?  Another question comes up: would that information be better served in a different article (Extinction)?  NYMFan69-86 (talk) 21:35, 3 March 2011 (UTC)
thread_title:  Critical number 

message: from the extant article:
"...inbreeding and genetic homogeneity increases and unfavoured alleles can accumulate."
Consanguinious relations over multiple generations yield a decrease in deleterious recessive alleles, not an increase in them.  Because inbreeding increases the probability of recessive traits being expressed, when those traits decrease the fitness of the individual, the individual is unlikely to survive long enough to pass the genes on to another generation.
--Vitki1963 (talk) 15:05, 27 August 2013 (UTC)
thread_title:  term 'unfavoured' needs quantification. 

message: According to its article in the Wikipedia the cheetah went through a population bottleneck, too. Should that be mentioned in the article?--Maxl (talk) 15:52, 2 September 2014 (UTC)
thread_title:  Cheetah 

message: "The animals living today are all descended (except those in South Dakota at the time), from 12 individuals ..."
This really could do with some explanation. What were European Bison doing in South Dakota? Were they reintroduced into the gene pool? -- Q Chris (talk) 12:17, 18 March 2020 (UTC)
thread_title:  European Bison in South  Dakota 

message: It seems as if the concept of genetic drift is misused in this article. In Wikipedia's article on genetic drift itself, it says that it's random, which is how I always understood it. But in the population bottleneck article, it is said to be a result of the bottleneck. That's not random. 142.254.109.112 (talk) 13:23, 13 September 2022 (UTC)
thread_title:  Genetic Drift 

message: FYI.
Subject articles:
NY Times: https://www.nytimes.com/2023/08/31/science/human-survival-bottleneck.html
Original paper: https://doi.org/10.1126/science.abq7487
—Danorton (talk) 14:24, 1 September 2023 (UTC)
thread_title:  930 Kya human population crash to 1,280 

message: The Neolithic Y-chromosome bottleneck refers to a period around 5000 BC where the diversity in the male y-chromosome dropped precipitously, to a level equivalent to reproduction occurring with a ratio between men and women of 1:17.[12] Discovered in 2015[13] the research suggests that the reason for the bottleneck was not a reduction in the number of males, but a drastic decrease in the percentage of males with reproductive success. 
This isn't correct.  The data doesn't necessarily show that only one man had reproductive success for every seventeen women (i.e., that a lot of women shared a few men), and the sources don't claim that.  It says that one Y-chromosome line survived for every seven mitochondrial lines, and the more recent source (and the paper it's based on) says that this most likely is due to differences in kinship impacts along the male and female lines.  For example, let's assume that Al and Ally are completely monogamous and have several sons and several daughters.  If all of Al and Ally's sons' sons' sons stay in the Alson tribe, but all of Al and Ally's daughters' daughters' daughters have married into a dozen surrounding tribes, then the Alson tribe dying out wipes out Al's Y-chromosome but not Ally's mitochondrial line, even though Ally and Al have (and always will have) exactly the same number of surviving descendants and therefore the same reproductive success.  And if this happens over and over with a whole bunch of patrilineal tribes, as it apparently did, then eventually you have a lot less Y-chromosome variation than mitochondrial variation.
I'm not sure how to express this in Wikipedia-style prose.  Can anyone help me with that?  Starry Void (talk) 06:24, 27 January 2024 (UTC)
thread_title: Neolithic reproductive patterns