Dear Henk,

To these examples of parthenogenetic freshwater snails, you may add at
least one, and certain populations of other, species in the genus Campeloma
(Viviparidae), which is endemic to the USA.  Despite this special
adaptation and the lengthy brooding of offspring in "utero," these
prosobranchs have not yet breached any zoogeographic boundaries as best I
can tell.

Of course, at least a majority of aquatic (basommatophoran) pulmonate
snails are hermaphroditic and can self-fertilize under proper conditions.

Harry


At 10:35 PM 2/16/01 +0200, you wrote:
>Dear James,
>Certain snails are selfreproducing when not a mate is available. An example
>among the landsnails is Rumina decollata. Among the freshwater snails
>parthenogenic reproduction occurs even more often. Populations of
>Potamopyrgus antipodarum (= formerly jenkinsi), an invading Hydrobiid snail
>in Europe originating from New Zealand,  consist usually solely of females
>and they are reproducing profusely. The same is true for Melanoides
>tuberculata. In all these cases a single female can start a new population
>without mating with a male. That's one of the reason why they are such
>successful colonizers.
>Best regards,
>Henk K. Mienis
>----- Original Message -----
>From: James M. Cheshire <[log in to unmask]>
>To: <[log in to unmask]>
>Sent: Friday, February 16, 2001 8:45 PM
>Subject: Re: Tropid
>
>
>> Dear Kurt,
>> I am not trying to give the impression that I consider my getting these
>> snails more important than the future of native species. I have a
>> question,
>> and it is simply out of curiosity. If only a single specimen of a foreign
>> species
>> was obtained for study, could it do any damage if it escaped? It seems to
>> me
>> that without a mate, it would not be able to reproduce, and therefor
>> would not
>> wreak havoc. I am now going to study just local snails, and, if the
>> theory above
>> is correct, I might have one Euglandina rosea.
>>
>> Best Regards,
>> James
>>
>> James M. Cheshire
>> (a.k.a. Jeremiah Chess)
>> 3185 Raccoon Valley Rd.
>> Granville, OH 43023-9472
>> USA
**********************************************************
Harry G. Lee
Suite 500
1801 Barrs St.
Jacksonville, FL 32204
USA   904-384-6419
<[log in to unmask]>
Visit the Jacksonville Shell Club Home Page at:
http://home.sprynet.com/~wfrank/jacksonv.htm

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