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Is extinction possible solely via competition?
Topic Started: Dec 17 2016, 03:06 PM (495 Views)
Thalanx
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Heterotrophic Organism
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Title says it all. Basically, does anyone know if there have been any cases of an animal going extinct solely because of competition with an exotic species, without any other factors contributing to the extinction (such as predation by exotic species and inbreeding)?
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Ceratodromeus
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I don't think i've ever read of this occuring; competition supplemented by predation is probably what does a lot of species in.
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Palaeoscincus
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Most if not all human caused extinctions are a combination of many factors even in cases where an animal has an introduced competitor, thats why it happens so rapidly. In prehistoric times, extinction happened through competition more but even then I dont think you could say solely. Lets say a new predator for example outcompetes an old predator when weather changes and the environment and prey distribution also changes, putting more pressure on the old one then it ever had. Would you only say old predator was solely outcompeted by new predator? Or would you say a environment change and prey evolution, combined with the pressure of competing with another predator drove it to extinction? I think its more the latter.
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Mesopredator
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Note I have a hard time remembering it from memory

Opilio parietinus has been outcompeted almost to extinction by Opilio canestrinii but they are the exact same niche (just notice they are the same genus).
Somewhat ironic I guess is the introduced crested mynah in urban Canada, which did fine until it was outcompeted by the common starling - I think it was.
Crested mynah is extinct in Canada now, but I understand that is not what you are looking for.

If you pick up a textbook on ecology (essentials of ecology) it will tell you that eventually competition would (should) lead to extinction, there's even a name for such a thing.
But can't remember it exactly, even though I read the book recently.

Species can avoid exclusion if the environment is dynamic enough or if there are refugia. For example there are many species of diving beetles with the exact same niche but they can coexist because diseases or other stressors might make one rarer at certain times.
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Mauro20
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The competitive exclusion principle says that two species that occupy the exact same niche can't coexist for long, eventually one of them would dominate this particular niche and the other would either go extinct or begin to explore different resources.
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Mesopredator
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Mauro20
Dec 31 2016, 04:40 AM
The competitive exclusion principle says that two species that occupy the exact same niche can't coexist for long, eventually one of them would dominate this particular niche and the other would either go extinct or begin to explore different resources.
I think that is what I was thinking of. Though can't remember it has to be the exact same niche.
Some generalists have been outcompeted by specialists and vice versa.

On topic:
Noisy miners in Australia according to Tim Low exclude almost all birds of forests they live in.
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Thalanx
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Quote:
 
Somewhat ironic I guess is the introduced crested mynah in urban Canada, which did fine until it was outcompeted by the common starling - I think it was.
Crested mynah is extinct in Canada now, but I understand that is not what you are looking for.

I think the climate might have had something to do with the extirpation of crested mynas there; mynas don't usually thrive outside of the tropics.

I think I read in a biology textbook that whenever competition occurs, both species can maintain populations as long as other environmental conditions don't change.
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Soopairik
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http://mentalfloss.com/article/75126/15-fast-facts-about-cheetahs

According to Mental Floss, cheetahs are on the decline due to them being naturally hard to breed animals. Their DNA is nearly identical to one another like clones. This means they might have interbred and even today, birth rates are low, and coupled with the fact 90% of cheetahs die before they are 3 months old, cheetahs are slowly dying off. While habitat destruction has played a major role, birth defects in cheetahs have also played a very big role.
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Grazier
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Weren't most extinctions caused solely by competition? When north america joined with south america for example, the vast majority of south american natives were rendered extinct by competition from the north american animals that flooded down. Today there is only a handful of truly native south american animals.
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SquamataOrthoptera
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If im not mistaken, Daeodon is said to be extinct due to competition by the Bear Dog.
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Soopairik
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I think Homo erectus and Neatherdals died out due to better species being better than them at living.
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Mesopredator
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Grazier
Dec 31 2016, 08:07 AM
Weren't most extinctions caused solely by competition? When north america joined with south america for example, the vast majority of south american natives were rendered extinct by competition from the north american animals that flooded down. Today there is only a handful of truly native south american animals.
In Thalanx's defense it could be due to predation, except for South America's original predators.

Another example:
Europe used to have a different bird group (source again Tim Low) but passerines originating from Australia outcompeted those.
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Thalanx
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Mesopredator
Dec 31 2016, 04:45 AM
On topic:
Noisy miners in Australia according to Tim Low exclude almost all birds of forests they live in.
Yes, and it's a rather controversial subject over there, because noisy miners are an endemic species, and most Australians firmly believe that natives can't be pests.

Even so, I don't think there are any species that noisy miners have pushed to the brink because of their habits (yet)

The yellow-throated miner, however, is driving the black-eared miner to extinction via hybridisation.
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