Date: Fri, 14 Jul 2000 12:55:14 +0200 From: strega@split.it (Tassara) To: cp@opus.hpl.hp.com Message-Id: <aabcdefg2110$foo@default> Subject: Re: Bird dispersion
Hi John,
>> Finally, with turions, they are somewhat resistant to drying out,
>> at least more than the plants. So, temperate varieties may make
>> it around this way as well.
>
>Sorry guys I still remain to be convinced.
>If bird dispersal was a serious contender then why is it that European weeds
>only made it to Southern Africa (and vice versa) when there was trade/
>travel etc.
>
>I thought that Aldrovanda seed was fairly rare and shortlived anyway...
They are rare in the European form, not in the tropical ones. However, they
are produced also in Europe in good growing conditions.
And are you sure they are shortlived (I don't know if there are data about
this; they would be interesting...)?
If eaten by birds and if they can resist there inside (why not? many seeds
do it and Aldrovanda's seem quite robust) they can be carried to a rather
long distance.
>and as
>for a bird carrying turions; Why would it? Even if the turions were hitching
>a ride in the birds feathers, would this stop them drying out (I dont think
>so).
Turions and plant fragments would probably not resist too long in the air
without drying out. However, they don't need to go very far to colonise the
next pond. To travel e.g. from Italy to Australia they would need many
years, of course, but they have had plenty of time.
In the past, bogs and lakes were much more common than today and such
dispersion was surely easy, also helped by occasional floodings.
Regards
Filippo Tassara
Genoa, Italy
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