Comment by estearum
5 hours ago
The usefulness of the term to this conversation is as described: is this species systemically critical to its current ("invaded") ecosystem?
Merely calling it invasive does not answer that question, ergo it is not a useful term in this conversation.
And yes, timescales do matter. A species can become critical to its new ("invaded") ecosystem within a few hundred years such that removing it within a few years will cause catastrophe.
What invasive species are critical to their ecosystem exactly?
Even in situations where they replace a native competitor, they can still be replaced themselves with that same native species once they’re gone.
And now we’ve come full circle to the uselessness of this label.
A species evolving in Area A and migrating to Area B is extremely common.
Camels, horses, marsupials, elephants, cats, opossums, New World monkeys, and even Homo sapiens all evolved in regions different than where they are found now.
Once they’re integrated into their ecosystems we just don’t refer to them as invasive. But calling something invasive or not doesn’t affect their ecosystem integration, causality works in reverse.
So the relevant question is, again, whether these have become critical to their now-local ecosystems.