Introduced species can wreak havoc on the ecosystems they invade. But what happens after they've been established for centuries? A new study in the latest Proceedings of the Royal Society suggests that, in one case, an introduced species has actually become an important part of the native ecosystem -- and helps protect native species from another invader [$-a].
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Recently a news article in Nature discussed ragamuffin earth [$-a] -- the idea that human interference in nature has so dramatically changed natural systems that it may often be impossible to restore "pristine" ecological communities. In these cases, some ecologists say, conservation efforts might be better focused on how to maintain and improve the diversity and productivity of the novel ecosystems we've inadvertently created. It looks as though the dingo could be a poster child for exactly this approach.
The havoc that introduced species have caused in some areas is well known, such as Australia (most prominently, but limited to, rabbits). But the term "invasive" seems more a normative than a scientific one, after all, at some point endemic species were invasive. For example, the "pristine" ecosystems of North American before Europeans arrived were certainly reshaped in the last 10,000 years by the migration of Old World species such as bison and the gray wolf, combined with human predation and utilization of fire. In fact recent research hints that the "virgin" Amazon rainforest may actually have taken up its present form after the die-off of native populations within the last 300-400 years.
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IIR, the domestic housecat (gone feral) is also wreaking havok in Australia and considered an invasive species.
Could our dislike of 'invasive' be little more than a psychological aversion to change? Maybe diversity is the only real goal that matters.
Exotica can really blast diversity; that's the main problem. No one really minds polite exotics that don't wreck the natives - who ever lost sleep over chicory?
I spent a summer in Minnesota, bustin' on monocultures of feral Rhamnus cathartica buckthorn. (Not recommended.) They cover acre after acre. I noticed a lack of birds (I'm a birder).
By the time I offed my zillionth bucky I was passionately in favor of biological control of the things, risky though it be.
Somehow this makes me think of a cartoon I saw long ago. It made gentle, self-mocking fun of earnest liberals, one of whom was driving a car with the bumpersticker, "Bring back Gondwanaland!"
How come no one ever mentions the most ubiquitous and planet altering invasive species. To find an example, find a mirror.
A new balance eventually arises when the old is destroyed. But it would be better to avoid destroying the old in the first place. A fire will eventually die out, but that doesn't mean that we shouldn't care about arsonists.
I grew up in the UK, lived in NW London but spent plenty of time in the country. Humans are definitely an invasive species. There is nowhere in GB that could be said to be "pristine wilderness". Even the places where there have never been farms or towns, the flora and fauna are definitely members of the "co-exist with humans" ecosystem, mostly domesticated life gone feral, often still in domesticated form. Even in the Fens, or the Lake District, or up on the Moors.
Ecosystems ( and perhaps many complex systems) are not necessarily threatened by changes, but they are hard pressed to deal with rapid rates of change. Invasive species are fundamentally a *rate* of change problem, as are many of the human caused changes to ecologies. There are exceptions to be sure, in biology there are always exceptions.
Today, we own the system. We be kings.
Until the earth burps again. Then back to protozoa!
That's the only REAL reason to colonize space, the further away the better. Many eggs, many baskets!
All full of genes, goop, glop, & guts aka DNA, protein, MtDNA of numerous diverse species.
I've worked a good bit in Venezuela. Out studying the pristines, don't you know. I was working out of Guanare. Come down one trip and the town is celebrating its 400 year aniversary. So that pristine forest over there is probably third or fourth growth. Or get really out in the jungle and discuss the local fish with a tribal indian, who knows them by the names used in the aquarium trade.
Re: Australia, add to the list:
Camels
Cane Toads
Carp