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How long does speciation typically take?

CplFerro

Graduate Poster
CplFerro
Joined
Jul 30, 2005
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As in, for a new species B, non-fertile with species A, to arise from species A. Any ideas? What's the shortest imagined (or recorded?) time?

P.S. Please don't tell me this is a meaningless question. It's not.
 
If you're talking fruit flys it could be a couple of years, if you're talking whales it would be a couple thousand millennia.
 
Apart from the obvious generation gaps, I would think it's mostly depending on a) if the enviroment changes a lot and b) how well the species can adapt to the changed enviroment in its current form (Us humans can now adapt to almost anything, and therefore only makes tiny and superficial changes).

EDIT: I realise I'm not really answering your question. Sorry about that, but I just don't know where you can find the info.
 
I recall hearing that rain forest ants can develop into a unique species during the life of the rain forest tree that their nest is located in. This gives alarmists the justification to claim that cutting a tree down has wiped another species off the planet. Hence the astronomical estimates of rain forest extinctions.

I honestly don't know if this is true. I'm trying to Google the subject but no results yet. My source was a radio show maybe 10 years ago.
 
YoPopa said:
I recall hearing that rain forest ants can develop into a unique species during the life of the rain forest tree that their nest is located in.
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Please let us know if you find out anything more on this. I'm not an entomologist (sp?) but I thought that ants were generally very slow to evolve since very few of the ants actually breed. Since nearly all of them are infertile workers, any adaptive advantage must arise within a couple key members of the colony or it will be completely lost.

Maybe I'm showing my USAcentrism by not knowing about south american ants.
 
CplFerro said:
As in, for a new species B, non-fertile with species A, to arise from species A. Any ideas? What's the shortest imagined (or recorded?) time?

P.S. Please don't tell me this is a meaningless question. It's not.
Click to expand...


Do viruses or bacteria count?
 
I recall something about one of the fruit fly experiments taking about 40 or so generations.
 
The amount of time it takes for a trait to emerge is dependent upon many environmental and species specific variables. Generally speaking, extreme conditions that push a population close to extinction will "sharpen the edge" and really draw out the individuals with successful traits. So, evolution can speed up and slow down based on the environment. However a long cycle of reproduction and maturity might not allow a species enough time to adapt. Other variables are the complexity of the species' genome. Take almond trees for example. Wild almonds have a cyanide based compound in them. Domesticated almonds do no have this poisonous trait because of a genetic mutation at a single point in the genome. A simple on/off switch which was selected for and allowed humans to easily domesticate and farm almonds. Furthermore, Speciation requires a separation of a segment of a species from the rest of the species so that its adaptations do not become diluted so the segment can become a species in its own right. So, we might see an acceleration of speciation in large mamals because the various groups of a species population are being segergated into wildlife refuges.

There is no simple answer to your question. Speciation is a complex interaction of genetic and environmental variables.
 
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I know I'm not answering in the spirit of the question... but it takes a single generation, always; in one generation, they can all interbreed; in the next, they can't. There might be some sort of incomplete division going on, but as far as I can work it out it has to be a single generation for the actual cutoff, doesn't it?

Now, how long does it take a newly speciated species to speciate again (ie, what is the inter-speciation time)? I think the standard deviation on that would be enormous, depending on the species and the instability (or novelness) of the environment.
 
It may not be a meaningless question, but that doesn't guarantee that it has a meaningful answer. Part of the problem is that even if everyone agreed that the "biological species concept" is the best way to define "species" (which not everyone does), neither fertility nor sterility can be regarded as binary properties as Jon has suggested; they are gradients. Try enough chimp/human matings, and you just might get one to take -- does that invalidate the chimp/human species boundary as a useful distinction? If not, where exactly do you draw that line? A judgement call at some point cannot be avoided.

With that in mind, the minimum resolution of the fossil record is perhaps fifteen to fifty thousand years, and with a gun to my head, that would be my answer.
 
Dymanic said:
Part of the problem is that even if everyone agreed that the "biological species concept" is the best way to define "species" (which not everyone does), neither fertility nor sterility can be regarded as binary properties as Jon has suggested; they are gradients. Try enough chimp/human matings, and you just might get one to take -- does that invalidate the chimp/human species boundary as a useful distinction? If not, where exactly do you draw that line? A judgement call at some point cannot be avoided.
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I hate to continue my hijack, but, whatever precise version of the biological species definition you choose, the actual speciation is a single generation. At some point, you call it 2 species. The generation before that wasn't called 2 species, so what was it? A species and a half? What I'm saying is that it was a population on the verge of speciation, but actual speciation would have to be in that single generation.

Of course, the question is really looking for how long that gradual progressions through the gradient takes, so I'll stop now. It's anywhere between a handful of generations (in organisms like fruitflies purposefully stressed to induce speciation) to probably tens or hundreds of thousands of years (in slower breeding creatures like whales).
 
Dymanic said:
Try enough chimp/human matings, and you just might get one to take -- does that invalidate the chimp/human species boundary as a useful distinction?
Click to expand...

Hoo, boy, wouldn't that experiment get the ethicists arguing? Chimp/Bonobo might be easier to justify, and since they separated more recently, your chances of success would be greater.

What are you aiming at with these questions, CplFerro? Are you trying to test out the timescale to see if there's sufficient time for all the required speciation?

Pick up Dawkins' latest book, The Ancestor's Tale. I haven't bought it yet, but a quick glance through it shows that it is quite heavily covering speciation and the branching tree of life. It might have the answers to these questions, in a far more informed and authorative (and likely well-written) format.
 
Species is a very specific term. It means 2 animals that cannot interbreed and produce fertile offspring. This is not subject to interpretation and thin lines.

<heavy speculation mode>
I think speciation can be a discrete event taking place in one generation. When by chance two individuals with the same genetic defect (e.g. extra pair of chromosomes) mate, they will produce fertile offspring that cannot interbreed with the original population. At least if the genetic defect isn't totally debilitating...
It this is the case, speciation would be very rare.
</heavy speculation mode> I could be completely off base here. As usual, lack of knowledge does not hinder the imagination, quite the contrary.
 
Evolution is very slow but the time span between new generations and the number of offspring also contribute to this equation. You really need to be looking at the number of generations and how readily the organism mutates, rather than the absolute time.

The Tree of life web page can tell you how far back species splitting occurred. For example, here is the Hominid Species Timeline. In the last 130,000 years the species, homo sapien, has not split and there is only one human race currently.

Certain conditions produce new species, namely isolation from the parent species and differing selection pressures. So when those conditions occur, species splitting is more rapid.

As far as hybrids go, there are probably more plant species and bacterial species hybrids than mammal hybrids (which have offspring less likely to be fertile). I don't know why that is. Maybe someone else knows. Most new animal species are not hybrids.
 
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Jon the Geek said:
I hate to continue my hijack, but, whatever precise version of the biological species definition you choose, the actual speciation is a single generation. At some point, you call it 2 species. The generation before that wasn't called 2 species, so what was it? A species and a half? What I'm saying is that it was a population on the verge of speciation, but actual speciation would have to be in that single generation.

Of course, the question is really looking for how long that gradual progressions through the gradient takes, so I'll stop now. It's anywhere between a handful of generations (in organisms like fruit flies purposefully stressed to induce speciation) to probably tens or hundreds of thousands of years (in slower breeding creatures like whales).
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I am afraid this interpretation of speciation is incorrect. Remember that the species we see today are the result of many generations of evolutionary pressure selecting for certain characteristics. Consider a series of generations of species A (so that A1 is the first generation A2 the second etc).

A1 A2 A3 A4....A100....A1068

Now, generations A1 and A2 can interbreed. Generations A12 and A4 can interbreed. It is quite possible that generations A1 and A100 can interbreed. However, Generations A1 and A1068 cannot interbreed. Therefore, generation A1068 can be considered a new species when compared to A1. But it is not a new species when compared to generation A1067 or A1000.

So, what happens to these transitional generations?

Assume A1 was already adapted to its environment, but a breeding pair moves to a new environment with a different set of evolutionary pressures. Individuals with the base A1 characteristics would be selected against, wheras those with characteristics of the A2/100/1068 are better adapted and flourish. Eventually the original A1/2/3 phenotypes disappear, leaving the better suited A1068.

What we observe is is the original species A1 and the new species B1 (which is really A1068), as all of the transitional generations have died and their characteristics were not selected for by evolutionary pressure.

This is why the creationists get so agitated about finding transitional fossils. But we are all transitional fossils (potentially).

The timescale for this is huge, and therefore your best chance of seeing speciation occur is in bacteria or lower order creatures.

The definition of species does not wholly hinge around interbreeding however. This has been covered before on Google and in these forums. Hope this explanation has helped...
 
What I'd be interested in knowing is if speciation can occur as a result of a long series of small mutations, or whether a dramatic chance event (a large mutation that just happened to yield a viable organism) is needed.

Edit: Took too long to post. In the meantime Dr Richard's post confirms the first option. It does leave me wondering how species with different numbers of chromosomes arise.
 
Dr Richard said:
The definition of species does not wholly hinge around interbreeding however. This has been covered before on Google and in these forums. Hope this explanation has helped...
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Would it be more correct to say that "A and B are different species" (ie define species relatively) while you can't say that "A is a species" (define species absolutely)?
 
BronzeDog mentions 40 generations being some sort of timescale for speciation (I remember having read that as well, though I think it was an experiment with beetles, take it for what it is ;) ), this could very well be close to correct. Evolution is not necessarily slow, 40 generations (of heavy preassure selection) is very fast, even for humans, a very slow species, this could be as little as about 600 years... Some bacteria could do this several times a day.

Also it is important to remember that speciation is not necessarily a serial process, but can just as easily be parallell, with species A spreading into a new environment and there splitting up into several species and thus entering more niches in the new environment. Or It could spread into several new environments at the same time.

I think there is some carpes (sp?) in lake Victoria or something that speciated into several species within the last couple of hundred years, talkorigins probably has something about that (I think that's where I found out about it).

Natural selection is a break (as in speed reducing element) in evolution, when it becomes weak, speciation can become faster (no natural predators might give raise to small "cultural" differences giving multiple speciation rather fast).

Or I might have a heatstroke :)

Mosquito - time to work a little again
 
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