Invasive Species

There is a definite tendency towards labelling native species as "good", and non-native species as "bad", not only amongst ecologists but the conservation community at large.

But what is a "native" species?  The English are rather fond of their English oaks, but the oaks which thrive in England today have only been there for the blink of an eye in geological terms.   In fact, these "English" oaks have spent 99% of the last two and a half million years in Iberia.

So what does native mean?  Is it

(a) where the species first evolved?

(b) the place you first think of when you hear its name?

(c) where they retain their greatest diversity today, or

(d) the place where they can best survive without human assistance?

In truth, all of these definitions have some merit.  So why do so many people have such strong opinions on non-native, invasive species?

The dingo was introduced to Australia around 5000 years ago.  It flourished, and in becoming the top predator in the country, drove the thylacine (or Tasmanian tiger) to extinction*.  Thus, not only is the dingo a non-native species introduced by man, but it had an adverse affect on established, native species.  

After 5000 years, and being well adapted to their surroundings, does the dingo qualify as a native species?  If so, at what point did it become so?

Of course, there are many examples of non-native species wreaking havoc on eco-systems - Gough Island, for one - but for every Gough Island there is an Ascension Island which has a tropical forest consisting almost entirely of alien species.

It seems incredible that the difference of a few years (in the scheme of thousands of years) could be the difference between a government spending millions on preserving the species or spending millions on eradicating it.

For a handy reference guide to Scottish Wildflowers (that's flowers found in Scotland regardless of where they came from), visit www.scottishwildflowers.org.

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