re: Ancient Relatives / Sundew Evolution

From: Ivan Snyder (bioexp@juno.com)
Date: Wed May 24 2000 - 10:08:11 PDT


Date: Wed, 24 May 2000 10:08:11 -0700
From: Ivan Snyder <bioexp@juno.com>
To: cp@opus.hpl.hp.com
Message-Id: <aabcdefg1629$foo@default>
Subject: re: Ancient Relatives / Sundew Evolution

Dear Jan and all,

Here is an ongoing dialog between Jan Schlauer an myself. Hope it does
not bore the rest of you. There is an evolutionary theory you might care
to ponder ( or in Jan's case, discredit :-) in my second quote below
which starts: Here is an idea ...

IS:
>> I have dissected the Scarlet Catchfly from here in California.
>>This plant has sticky glandular trichomes and does capture insects. The
>>plant is similar in many features when compared to Drosophylum

JS:
>The gland structure is much simpler in _Silene_, and these organs
>(in Caryophyllales) are quite certainly not homologous to the
>glandular structures (Licopolian glands) in Nepenthales. The fact
>that they are sticky is the only remaining similarity.

IS:
Here is an idea. Often we see tentacles in Drosera where only sticky
trichomes should be, on the scape and bracts. I have seen a few times
sundew malformities where flower styles and tentacles had been fused
together, and also tentacles replacing styles. This has led me to believe
that perhaps this is how tentacles evolved in sundews. Consider that
styles are protein sensitive and capable of movement. Maybe the first
sundew had simple glandular trichomes united with styles? If all this is
true, then the same genes involved in construction of styles in Drosera
will also be expressed in tentacle construction. Anyway, maybe we should
not just compare trichomes with tentacles, but instead compare tentacles
to styles.

IS:
>> , the most primitive sundew,

JS:
>I have tried in previous messages to make clear why I think that
>_Drosophyllum_ is not a sundew.

IS:
Sorry, Portuguese Sundew ( Drosophylum common name).

IS:
>>I don't know if Drosophylum and Silene are in fact related, but I would
say that Silene is at least representative of a >>link between
>>CP and nonCP.

JS:
>They are (both are caryophyllids, as far as genetical/chemical data
>are reliable). But there are additional families in between. (---)
>From a structural/functional viewpoint this is certainly true.

IS:
Again, I am not convinced that the Catchfly and Drosophylum are truly
closely related. I will leave that judgement to you. I could collect
herbarium material and seed of Silene laciniata for you to study if you
are really interested.

Ivan Snyder
Hermosa Beach
California



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