Outer bark variation

Bob Vickery vickery at MPX.COM.AU
Wed Oct 22 08:36:09 EST 1997

qdurham at aol.com (QDurham) wrote:

>>I don't know of any adaptations shown by bark.  Variation in bark characte=
>> is one of god's gifts to botanists.
>>Eucalyptus trees show great variation within a locality: gums, boxes,=3D
>> stringybarks, peppermints and iron-barks can all grow close together,=3D
>> though they are different species of course.  Conversely, one type of bar=
>> can be found in very different environments - again on different species.
>These aren't adaptations?

Not in my book.  I think of adaptations as variations that improve the=
 fitness of an organism in its environment. I don't see how variations in=
 bark are adaptive.

Many biologists believe, like Candide, that everything is for the best in=
 the best of all possible worlds.  Or, in more biological terms, that every=
 stable variant helps to maximise the fitness of the organism in its present=
 environment.  They justify their beliefs by inventing explanations, not=
 always convincing, for each variant.

Some variations are undoubtedly adaptations, but it is not self-evident that=
 all of them are.  They may have arisen in the past in different=
 environments and be no longer adaptive.  They may come from genetic drift.


Bob Vickery
bob at acsusun.acsu.unsw.edu.au
vickery at mpx.com.au

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