Dear Alex,

Thank you for your very informative report. The literature is biased
toward the odd occurrence of a sinistral mutant. Collections are
also! The tendency is not to report the lack of such occurrences in
substantial samples such as your prodigious experience provides. A
journalist would liken the your report to "dog bites man;" what his
editor (and the readership) wants is the opposite - "man bites dog."
That's no way of getting a handle on the frequency of either form of
canine-hominid aggression.

Similarly, only when more than one specimen is found in a single
"sample," can we begin to impute the frequency of reversal. Such a
situation rarely presents itself, but the three references I gave in
an earlier posting and the experience of certain legendary collectors
like Phil Poland (see <http://www.jaxshells.org/philp.htm>) can begin
to yield an understanding. Thus far two things are reasonably clear:
(1) Most gastropod species have never been found to have a reversed
mutant (that means reversalis very rare by species across the
taxonomic breadth of the Class), and (2) the observed frequency of
such anomalies, when it can be inferred with some level of accuracy,
varies widely from species to species. The hint that biological
perturbations such as parthenogenesis (Campeloma) and selective
breeding (Laciniaria, Lymnaeidae, Cornu aspersum, and maybe others)
may allow perpetuation and increased frequency of reversed mutant
stocks allows us to understand a tiny bit more of the higher
frequencies of reversed mutants in certain taxa and populations..

Harry


At 04:37 PM 7/16/2006, you wrote:
>Hi to the sinistral people
>
>I have hundreds of thousands of specimens in my land mollusc collection. I
>have also examined at least an equal number in the field over years of
>fieldwork.  I also examined, and categorized into juvenile, sub-adult and
>adult, almost two hundred thousand individuals of almost 100 species for the
>Biogeographical part of my PhD. I have only ever come across a single
>sinistral specimen. This was a Vallonia and I had a pleasent surprise when I
>examined it with my microscope. Having looked at many examples of large
>populations of, e.g. Theba, Cochlicella etc. and not having found a single
>one, leads me to believe that sinistral specimens are not that common. Even
>very abundant species, such as Achatina fulica rarely throw up a sinistral
>individual (cf Tucker Abbott, 1989, Comp. where this is given as form
>sinistrosa). These fetch very high prices on auctions and are quickly
>snapped up by collectors (I confess to having bought a few myself).
>Sinsitrality is related to genetics and early development (cf classic works
>by Garstang). There is the odd reference to sinistrality in the older
>literature (as for monstrosities) because these were highly sought after by
>collectors, especially Victorians. I'm sure I must have left something out
>(excuse the pun!).
>
>Alex
>
>-----Original Message-----
>From: Conchologists List [mailto:[log in to unmask]]On Behalf Of
>Stephanie Clark
>Sent: 16 July 2006 21:37
>To: [log in to unmask]
>Subject: Must be sinistral month
>
>Hi to Harry and other interested parties
>
>I have a new species to add to the list of normally dextral species, having
>a sinistral individual Lioplax pilsbryi (Viviparidae) before me.
>
>Last Saturday (8 July) David Campbell (fellow conch-ler) and I were on a
>day field trip sampling some spots on the Yellow and Pea Rivers in southern
>Alabama and just into Florida. We were looking for mussels and hydrobiids
>(freshwater snails, that those of you who attended COA this year learnt all
>about!) in particular.
>
>The spot on the Yellow River, where the specimen which is currently
>crawling around under my microscope, was found was just east of Wing, in
>southern Alabama. In fact I have visited this spot now three times since 22
>December 2005, looking for a particular hydrobiid, to no avail. However the
>first two times the river was more than a metre higher than it was last
>Saturday, not to mention decidedly warmer. On all three occasions I found
>Lioplax and Campeloma, crawling in the sand along the edges of the river, I
>almost didn't pick any up, but they were in front of me so I kept a couple
>for the record. I didn't notice the unusual Lioplax in the river, in fact I
>thought I had picked up a largish Physa and thought nothing more about it
>until the next day when I was checking the samples to label them and freeze
>some of the material I had found. This is when I noticed that my big Physa
>was in fact a small sinistral Lioplax.
>
>This is now at least the second time I have found a sinistral version of a
>normally dextral species in the last 10 months, the other was a hydrobiid,
>but I will have to find the lot again, this one I noticed when I was
>sorting some samples collected in the previous two years from Alabama and
>Florida. When I relocate that lot I will let Harry and the rest of you know
>what species that was. I had been meaning to send a note before about the
>hydrobiid but having another live sinistral snail, has prompted my memory.
>
>Stephanie

Harry G. Lee, M. D.
4132 Ortega Forest Dr.
Jacksonville, FL 32210 USA
voice (904) 389 4049
email: [log in to unmask]
look at www.jaxshells.org

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