My thought process is that, after enough time, an invasive species of some plant or animal would find its way into its new ecosystem, and properly become a part of the ecological cycle? Does this ever happen? Maybe it just needs far more time to do so?
In: Biology
Whether or not a species is invasive depends on if it can fit into the ecological cycle. Not all non-native species are invasive. Bees, earthworms and some horses are not native to the Americas but are generally not considered invasive species.
> after enough time
Correct. After a few tens of thousand years. On the way there, they cause the extinction of several species that cannot adapt fast enough, resulting in a much changed ecosystem than before them.
This isn’t great if
1. You don’t have a couple historic eras to wait stuff out
2. You *like* how stuff is right now and do *not like* how the newcomer is killing off all your favorite species in job lots.
Dingos were introduced to Australia about 5000 years ago and they are considered native. Same as a number of placental rodents.
Invasive is a human term.
We decide pretty much arbitrarily if something is considered invasive or not.
My favorite example of this is Hawaii when the government decided to remove some “invasive” plants and animals.
Animals and plants that turned out to be religiously important to the native population. At which point the native Hawaiians asked… are we not native?
You’re right but, on a human time scale, if you introduce a species to an isolated island and it wipes out most of the native species, it will take tens of thousand so of years, maybe millions for species to evolve to replace the ones lost.
They will eventually become part of the ecosystem but it will usually come at the cost of a lot of the original species becoming extinct both animal and plants
Yep. Over an extensive evolutionary cycle the ecology will reshape.
This can be incredibly drastic not just on what lives their but also the terrain itself. And the term is also not limited to insects and animals, plants as well can be considered invasive.
The reason the term is invasive is typically the shift is a consequence of human action and its disruptive to the existing equilibrium.
Its very easy for things to domino out of control, and we wont have a way to “fix” things if they fall out of our favor short of waiting.
Waiting a few Ten, Hundred, or Thousand years for a new stability is-
Not ideal when alternatively we can maintain the stability that currently exists
It would, but in the process it would displace other species. Those other species might become extinct. Species that eat those other species might become extinct. Eventually you would have a much smaller number of species, distributed all over the world. If you like biodiversity, this would be bad.
Some invasive species are a threat to agriculture. If a plant isn’t edible, but outcompetes edible plants, that’s obviously going to cause problems for us.
Think about it this way — in about 100,000 years almost all traces of above ground human infrastructure will be gone, but many of the species we imported will still remain. The example I always think of is Japanese knotweed in many parts of the east coast — this plant will surely be around in places it’s not native to long after humanity is gone. In that way, it will always be “invasive”.
Something that might not have been mentioned is how invasive species destroy native organisms. Evolving in conjunction with the thing that will harm the organism gives it defensive traits and allows the species to carry on. Organisms usually produce significantly more offspring than will survive. Think about how five thousand fish eggs will only produce a handful of mature and reproductive organisms. So, when a species enters a new ecosystem devoid of predators, they are going to thrive and take over resources in the new ecosystem. Imagine how it works if the five thousand fish eggs hatch because they weren’t eaten by something else before hatching. From that point on, it’s a devastating domino effect. Of course, as has been mentioned, plants and animals can be introduced without being harmful.
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