Talk:Allopatric speciation

Adaptive radiation

How does adaptive radiation differ from allopatric speciation? Allopatry begins when subpopulations of a species become isolated geographically (for example, by habitat fragmentation or migration). The isolated populations are then liable to diverge evolutionarily over many generations. As far as I can tell, this is the same as adaptive radiation, but maybe I am overlooking a fine point. RK 16:08, Aug 12, 2004 (UTC)

You're not overlooking a fine point, there's quite a distinct difference. Adaptive radiation occurs when a species is introduced to an ecosystem, hitherto unreachable, and can fill a variety of ecological niches. The most frequently quoted example is Darwin's finches - 14 species evolved from a single species introduced on the Galápagos Islands. Allopatric speciation occurs when two populations of a single species, separated by a physical barrier (eg a channel of water) become isolated both geographically and reproductively to the point that if the barrier breaks down, they are unable to interbreed. So adaptive radiation is just what it says - 1 species radiates into a variety of species, IN ORDER TO fill the niches; allopatric speciation - 1 species effectively becomes 2, THROUGH REPRODUCTIVE/GEOGRAPHIC ISOLATION.

Hope that helps. By the way, there was no need to revert my comment, it's just some harmless fun. There's no rule about not making a little joke on the discussion page. It was patronising, and insulting. It's not as though I don't know what I'm doing here. ^Triana_C 03:49, 15 June 2006 (UTC)

Alright then, another comment. Where did this 8 generations or more number come from (in the example picture of fruitflies)? As you know with certain bacteria that could take place in a day. As far as i was aware speciation had never been observed (asides from perhaps postulation from mDNA 'clocks' i suppose) so its unlikely to be a missing reference. So is this science or speculation on the 8 generations?

The image is based on a very similar diagram which simply mentions "many generations pass". I don't know why the artist specified a lower limit of eight generations, but it seems a relatively minor mistake to me. Speciation has been observed, for instance these examples. Ppe42 21:53, 22 February 2007 (UTC)

Removing Fruit Flys

I'd really like to remove the fruit fly picture because it does NOT take 8 generations to have a new species of fruit fly. I want to know if this is a good idea.

- WarriorFIRESTAR (talk) 20:33, 21 October 2008 (UTC), thanks.

Do you have a citation to support your claim? I assume the image is based on the published article it cites. --98.217.8.46 (talk) 21:01, 21 October 2008 (UTC)

Disagree with removal in lieu of a citation that it is fundamentally flawed. "Eight generations" is not (yet) specifically cited in the image, but is cited at the more general speciation article. — Lomn 21:12, 21 October 2008 (UTC)

Geographical isolation Suggested Merger

Is Geographical isolation merely a poorly worded version of this topic? It certainly seems that that article as written is relating the same information as Allopatric speciation. If so, should one be redirected?--JimmyButler (talk) 18:31, 7 October 2010 (UTC)

After close analysis of the two articles; it seems a possible solution would be to merge the two; although in reality although the content is nearly identical; thus one is merely be deleted.--JimmyButler (talk) 14:07, 8 October 2010 (UTC)

I support the merge, or possibly a deletion of Geographical isolation and the establishment of a redirect. As it stands, the two article are very similar.--NYMFan69-86 (talk) 15:54, 8 October 2010 (UTC)

Take these two sentences:

• (From Geographical isolation)-" [...]evolve characteristics different from the parent population (due to genetics/genetic) change following geographical isolation, then if the geographical barriers are removed (perhaps due to human activity), members of the two populations will be unable to successfully mate with each other.
• (From Allopatric speciation)-" [...]biological populations are physically isolated by an extrinsic barrier and evolve intrinsic (genetic) reproductive isolation to the extent that if the barrier should ever vanish, individuals of the two populations could no longer interbreed."
  --NYMFan69-86 (talk) 02:23, 9 October 2010 (UTC)

OK, I performed the merge. There is quite a lot of tension within the text though. --Ettrig (talk) 09:56, 10 October 2010 (UTC)

I think it's the right move. Work and expansion to be done.--NYMFan69-86 (talk) 20:48, 10 October 2010 (UTC)

Wouldn't geographic isolation also be involved in peripatric speciation? Ucucha 00:59, 19 October 2010 (UTC)

Mmmm...good point.--NYMFan69-86 (talk) 17:13, 19 October 2010 (UTC)

Quoted: "In parapatric speciation there is no specific extrinsic barrier to gene flow. The population is continuous, but nonetheless, the population does not mate randomly. Individuals are more likely to mate with their geographic neighbors than with individuals in a different part of the population’s range. In this mode divergence may happen because of reduced gene flow within the population and varying selection pressures across the population’s range." I've yet to see a text reference this as a type of geographic isolation - perhaps because there is technically no "isolation" in that there are no geographic barriers only preferential mating. Campbell Biology equates allopatric with geographic isolation - the term seeming to be synonymous. The articles in separation had essentially identical explanations describing the same process and outcome. I think / hope the merge was appropriate.--JimmyButler (talk) 19:14, 19 October 2010 (UTC)

I mentioned peripatric, not parapatric speciation. However, peripatric speciation may be a special case of allopatric—and perhaps it is hard to sort out the different concepts that are used in the literature. Ucucha 20:07, 19 October 2010 (UTC)

There appears to be a fine line between genetic isolation, allopatric speciation, and peripatric speciation. I think a harder look at scholarly sources will help (as the two articles [allopatric and peripatric speciation] stand right now, refs are slim).--NYMFan69-86 (talk) 01:14, 20 October 2010 (UTC)

My "bible" on evolution is Evolutionary Biology, 1998, by Douglas Futuyma. It has very similar illustrations of four models of speciation on p. 483. In the chapter about "Kinds of Allopatric Speciation" it describes peripatric evolution with "The other major mode of allopatric speciation ... Mayr ... called this peripatric speciation". Futuyma refers here to Mechanisms of Speciation, pp. 1-19 in Alan R. Liss, New York, 1982. --Ettrig (talk) 19:55, 20 October 2010 (UTC)

Sorry... peri vs. para. I dug through some journals as well - enough to realize that the vocabulary and its application is a contentious topic - reminiscent of the definition and use of the word species. What I can gather - peripatric is a form of allopatric involving speciation among the peripheral populations at the geographical fringes.--JimmyButler (talk) 13:36, 21 October 2010 (UTC)

Reproductive isolation

Reproductive isolation is not the only definition of species. But much of this article seems to assume it is. --Ettrig (talk) 09:56, 10 October 2010 (UTC)

Quite right. The text needs a fair bit of work...not to mention more sources to pull information from.--NYMFan69-86 (talk) 18:59, 10 October 2010 (UTC)

If I remember correctly from long-ago courses - hasn't the definition of species always been a source of raging debate among the learned?--JimmyButler (talk) 23:23, 10 October 2010 (UTC)

If my 6 weeks of college education have taught me anything, its that two members of the same species (opposite gender of course) can mate and produce a sexually viable offspring while two individuals of different species cannot.--NYMFan69-86 (talk) 00:25, 11 October 2010 (UTC)

Yes, raging for a long time, because organisms are not always neatly divided into species. There are many more interesting weeks to come. Consider for example dandelion (apomixis) and bacteria (no real sex, although mixing of genes does occur). --Ettrig (talk) 10:53, 12 October 2010 (UTC)

The finch example

I thought this was the classic example of adaptive radiation, something a bit different than allopatric speciation (or are they really the same)?--NYMFan69-86 (talk) 00:28, 11 October 2010 (UTC)

I haven't seen this discussed explicitly. My own interpretation is that allopatric speciation cocerns the "small" event that creates a new species, while adaptive radiation concerns a much wider observation that several daughter species from the same original species tend to be rater different. Spelled out this way, adaptive radiation sounds like a rather trivial concept, and I think it is. Anyway, it is not unreasonable that the same group of organisms is an example of both phenomena. --Ettrig (talk) 11:01, 12 October 2010 (UTC)

That makes sense to me. I suppose there's a fine line between the two.--NYMFan69-86 (talk) 23:44, 12 October 2010 (UTC)

Question

From the first paragraph: "At this point, a new species has emerged."--wouldn't it be more correct to say two new species have emerged...each a different species than their common ancestor?--NYMFan69-86 (talk) 01:02, 13 October 2010 (UTC)

It may need some tweaking; however, whether two "new" species have emerged depends on whether both undergo evolutionary changes that sufficiently distinguishes them from the ancestral population. I guess it is possible that if you split population "a" into two groups "b" and "c" - and only "c" evolves significant characteristic changes then technically only one new species evolved. Of course "both "b" and "c" may diverge from the original form - in which case two new species would be appropriate. That said - I guess I should go read the context of the sentence in questions. I'd like to keep dorking with article as time allows. It is of interest and could use some work. My apologies for not citing as I go, I'm using lecture notes at the moment; however, I will get around to citing. Yes - shame on me:( PS I got around to reading the painted turtle - very well executed! Are you contemplating FA?--JimmyButler (talk) 01:36, 13 October 2010 (UTC)

Yeah...I think before too much contemplation occurs, some references would be good (not to say your beastly lecture material isn't sufficient or anything!). My sights for that article are on GA for now...the Wood turtle is what I have in mind next for FA (perhaps a month or so away from getting around to adding some of the more "abstract content"...if you catch my drift). The painted turtle is up for peer review as of a few minutes ago.--NYMFan69-86 (talk) 18:15, 13 October 2010 (UTC)

Social change

This section starts with talking about social reasons for allopatric speciation...but than kind of falls off onto another topic. Is the other information to be put somewhere else? --NYMFan69-86 (talk) 18:06, 15 October 2010 (UTC)

Adaptive radiation

I think it is incorrect to say that "adaptive radiation ... is a form of allopatric speciation". These concepts are on different scale. Allopatric speciation is when one new species is generated (or two emerge from one by a split) under a particular condition (allopatry). Adaptive radiation is when many species emerge in a short time. Yes, allopatric speciation may have been the manner in which all the species emerged in the adaptive radiation. Still, this does not make the radiation a form of speciation. Radiation is a form of a (large) group of speciations. --Ettrig (talk) 17:40, 17 October 2010 (UTC)

I may be a biology major...but I'm still a freshman! I don't really know...professor?--NYMFan69-86 (talk) 18:02, 17 October 2010 (UTC)

I agree. The speciation leads to adaptive radiation, but they are not the same thing. As always, I'm open to being overruled by a an opinion from a reliable source. William Avery (talk) 18:18, 17 October 2010 (UTC)

Actually, that was a direct quote; ummmm from where thou. The importance of citing as you go. I'll strike it for now and instead use adaptive radiation in island populations as the classic example of allopatric speciation. Adaptive Radiation is a consequence of allopatric speciation - perhaps that is the point we need to establish?--JimmyButler (talk) 14:05, 18 October 2010 (UTC)

New Section Peripheral populations

The info being added is gleaned from a variety of biology text; I suspect it is common knowledge within the field - however, look for misrepresentation of facts as I reword the text for simplification. I hope to seek out some online sources that are accessible to validate. Some of the original material that I've left in place gets a bit technical. I'll need to understand it before any attempt is made by me to edit or delete. There are numerous examples of allopatric speciation - especially in island populations. I'll work them in or add to example section - although I don't like the heading "Examples". Might be a while before I can get back to it... so a citation needed tag may scar the landscape.--JimmyButler (talk) 15:01, 18 October 2010 (UTC)

Providing examples in an effective manner is, I think, going to be the hardest part of this article. It shouldn't be difficult at all to find an adequate number of examples in credible literature, however incorporating them in the article seems like it will be a challenge.--NYMFan69-86 (talk) 16:18, 18 October 2010 (UTC)

Wording

• I see the phrase "allopatric speciation may occur" a lot in the article. Is the word may always necessary, shouldn't the prose discuss the circumstances under which allopatric speciation do occur?--NYMFan69-86 (talk) 21:29, 22 October 2010 (UTC)

• "First, the peripheral isolates are likely to possess genes that are different from the parental population since such populations tend to represent the extreme genotypic composition."--I personally know what this sentence is saying, but some may be confused about which population the word "population" is referring to here.--NYMFan69-86 (talk) 21:44, 22 October 2010 (UTC)

• "However, if it is of founder effects, or if the population becomes isolated in an environment which makes new demands upon it."--was there originally supposed to be another portion to this sentence?--NYMFan69-86 (talk) 21:47, 22 October 2010 (UTC)

Extreme periphery

This passage: the peripheral isolates are likely to possess genes that are different from the parental population since such populations tend to represent the extreme genotypic composition is circular. It says that the genes in the periphery are different because they are extreme. Could it be that the intention is to say that because the edges of the area tend to have extreme properties (for the area), selection tends to produce extreme phenotypes in the periphery. ? --Ettrig (talk) 10:23, 23 October 2010 (UTC)

'Genesis of reproductive barriers' - garbled text.

The current (16 Dec 2010) article includes the text:

"However, if it is of founder effects, or if the population becomes isolated in an environment which makes new demands upon it. Research has shown that this is a major reason why so many different species exist throughout the world."

The first "sentence" is garbled, ungrammatical and of no clear meaning (this is not a broken edit, it was garbled like this from first insertion). However, removing this text (possibly) removes the anaphoric referent of the "...this..." in the following sentence. Since this second sentence cites no evidence for its claim, which is extravagent whatever the "this" refers to, I have removed both sentences. If anyone understands the real intent of this text, please insert a clearer version. FredV (talk) 13:05, 16 December 2010 (UTC)

The offending sentences seems to have been brought over with Geographic Isolation when the two separate articles were recently merged. Whether it made sense there - who knows. "This" was the evidence needed to finally prove Evolution to the masses. Too bad we have no way of ascertaining what "This" actually was. Thus deletion is appropriate.--JimmyButler (talk) 15:19, 16 December 2010 (UTC)

I noted this in my "wording" section, but was hesitant to delete it because it seemed important. However, if it doesn't make sense and isn't cited, what else can one do?--NYMFan69-86 (talk) 17:40, 16 December 2010 (UTC)

3 Suggested Improvements

1. There was no mention of migration or founder effect which can also lead to allopatric speciation. 2. In the first paragraph the author writes "the vicariant populations then undergo genotypic OR phenotypic divergence..." which would be better phrased as "populations then undergo genotypic AND phenotypic divergance..." because to have phenotypic change there must be a change in genotype and for speciation to occur phenotypic changes must occur. 3. One thing that should be added to the article is how scientists define two separate species, which can be a tricky subject and should be explained thoroughly for the readers. — Preceding unsigned comment added by Ryan.332 (talk • contribs) 03:27, 1 October 2014 (UTC)

Elephants

Where is the research showing that these Elephants can't mate? HealthClarity (talk) 20:33, 12 April 2016 (UTC)

Vicariant especiation

Leon Croizat coined the term of vicariant speciation and precisely his proposal is based on a clear distancing from the Darwinian notion of allopatric speciation. Thus "vicariant" is different from "allopatric". Fernando Otalora Luna (talk) 19:06, 4 October 2019 (UTC)

Progression rule

A lot of these different topics all seem to intersect with and duplicate other treatments of same or similar topics. This caption -- "Allopatric speciation can result from mountain topography. Climatic changes can drive species into altitudinal zones—either valleys or peaks. Colored regions indicate distributions. As distributions are modified due to the change in suitable habitats, reproductive isolation can drive the formation of a new species." -- reminded me of Willi Hennig's progression rule, which was extended by botanists Vicki Funk and Warren Lambert Wagner to describe Hawaiian island biogeography,[1][2] in particular, the pattern of evolutionary history that moves down the chain of Hawaiian islands, from the older ones to the younger ones. How does this version of the progression rule, which incorporates geological history, fit in to allopatric speciation? The image that the caption refers to in this article (allopatric speciation by topography) almost illustrates the progression rule if you apply it to Hawaii and point the arrow in one direction. Viriditas (talk) 22:28, 1 October 2023 (UTC)