I'm not asking about an exotic species in the modern world we know all too well the havoc that can be caused by the introduction of an alien species into an existing ecosystem. I want to know if a novel evolutionary adaptation could create a species which wipes out the rest of the ecosystem it evolved in.

In particular I'm wondering if something similar to the Manchineel could evolve and through a relatively minor mutation and change in it's biochemistry kill off the rest of the ecosystem around it and then take over the newly vacant floral niches?

For the purposes of this question assume a bare-bones ecosystem without land-dwelling vertebrates or grasses but with trees flowers and insect life. Furthermore assume the plant taking over is in fact wind pollinated and thus independent of other organisms for it's propagation. I'm wondering about how realistic causing the total extinction of other multi-cellular life on land is rather than simply forcing other lifeforms into niche environments.

This is an extension of some ideas spurred by Why wouldn't my colonists go to see what's going on down there? and Planet with no rain, only fog, like Chile's Atacama Desert, reference to which may or may not be helpful.

Other possible plant touchstones may include Yew and Locust which are toxic not only to people and animals but also to other plants that would otherwise compete with them.

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    You mean like how some early life poisoned most of their competitors by changing the atmosphere to oxygen-rich? – user535733 Oct 16 at 14:06
  • @user535733 Kind of except with a far more evolved biosphere and actually forcing it's competitors into extinct rather than relegating them to niche environments. – Ash Oct 16 at 14:08
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    How fast do you want it to happen oxygen took millions of years. – John Oct 16 at 14:16
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    You mean like how the family homo is well on the way to destroying the remaining ecosystems it hasn't already completed? – Carl Witthoft Oct 16 at 18:46
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    @Ray I'm thinking something on the scale of the difference between producing Taxine A and Taxine B a small shift in terms of chemistry, possibly quite a large shift in genetics I'm not sure. – Ash Oct 17 at 10:27

One example I could think of is grass itself.

Through a simple evolutionary step (fairly recent in the overall evolution of life), that of propagating underneath the soil instead of above it with rhizomes, the plant quickly destroyed all opportunity (and strangled standard trees) for pre-existing trees to grow.

It does this by pollinating through air (as you mentioned), covering the available land, with complex interwoven root systems that completely eliminate older tree-like individual stems and roots. Even fire cannot destroy the plant as the roots underneath are unaffected. Any plant that tries to grow amongst grass is quickly strangled. Any animal that eats it only affects the plant above the surface, but eaten portions are easily replaced.

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The evolution of grass has been so successful that huge swathes of continents had their preexisting jungles and ferns replaced entirely with grass.

In terms of plant species that you mention that wipe out established eco-systems, you need look no further than simple grass.

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    grass did not evolve through a single mutation. – John Oct 16 at 17:29
  • hmmm... have you read Sheri Tepper's "Grass" ? – Carl Witthoft Oct 16 at 18:46

No

You are not talking about a single mutation but a sudden drastic change in the plants biochemistry without killing said plant. A mutation will not produce this. Toxicity takes many many generations to evolve and almost as long to build in concentration.

The only way you will do this is with a species introduced from outside the ecosystem, one that the local wildlife has not been evolving alongside. Note this can still be completely natural, plants get to new islands in bad storms or in bird poop, they can travel hundreds of miles this way. The key is the the local wildlife has no defense against the new plant because it was not present in the environment before. for a benign example the cattle egret made it from Africa to the americas on a storm and has spread like wildfire ever since.

  • Toxicity in general certainly takes time to evolve but does the change from a toxin that other lifeforms can tolerate in very low concentrations to a closely related but different toxin that they can't have to take time periods of the same order? Or in fact a small but telling change in the rate of production. – Ash Oct 16 at 14:30
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    no, said toxin will already be present in the environment for things to develop a resistance too. worse as a broad spectrum toxin (you want it to effect animals and plants) the plant that has it will need to have increasing measures to not poisons itself so a sudden change may kill it. toxicity has evolved many times and resistance evolves right along side it. because it cannot evolve too quickly. – John Oct 16 at 14:34
  • I'm not talking about it evolving gradually I'm talking about a sudden change, which could have killed the whole ecosystem but the species producing it got lucky. – Ash Oct 16 at 14:37
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    No that's not how mutation works, you can't have that sudden of a change in a species, you can get it by introducing a new species, but not by changing an existing one. keep in mind broad toxins are also toxic to the things that produce them. If it evolves quickly it will kill itself long before it can spread. – John Oct 16 at 14:40
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    Broad toxins are usually many combined toxins, the death apple is a great example. even then there are things that eat them. For single toxins a good rule of thumb is the larger a variety of things a toxin effects the more basal to the machinery of life it is and thus the slower it has to evolve to not kill the thing producing it. – John Oct 16 at 16:25

Yes

The new species can completely transform the "look and feel" of the landscape. Even without toxins, invasive species are wreaking havoc. The toxin would be yet another advantage.

No

Life in general is incredibly resilient and good at filling new ecological niches as they develop. Compare extremophile lifeforms, or for that matter multiresistant microbes. As the new lifeform spreads, many other individuals are killed. Entire species will die. But those individuals which are not killed immediately will breed into ever more resistant strains.

So the new plant might become dominant in the old ecosystem. It won't replace all other lifeforms.

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