Since one runs into these in mollusk papers, it may be helpful to
review (or state) the definitions.

A synapomorphy is a shared feature distinguishing a group of organisms
that are related.  The radula in mollusks is one example.  (As in many
examples, the feature has been lost in certain groups-organisms do not
always do a good job of carefully making their affinities obvious.)
The presence of two shells throughout shell growth in bivalves is
another example of a synapomorphy, although one might raise the issue
of accessory plates in the pholadoideans and the form of the lasidium
larva as caveats.

A homoplasy is a similarity that evolved separately.  The bivalved
condition in bivalves and in juliid sacoglossans is an example-both
independently developed two shells for similar functional reasons.

On Thu, Nov 1, 2012 at 9:31 AM, Harry Lee <[log in to unmask]> wrote:
> Dear Listers,
>
> A kind and wise correspondent has pointed out a malapropism in my posting of
> yesterday AM.
>
> My use of the term "synapomorphic/synapomorphies" was improper. I should
> have use "homoplastic/homoplasties" in its place. I've emended the posting
> below
>
> Sorry,
> Harry
>
>
> A few years ago we mentioned a separate lineage of snail-eating snakes in
> Asia, the Pareatinae, and Aydin Orstan followed up with a blog at <
> http://snailstales.blogspot.com/2007/02/evolution-of-jaw-asymmetry-in-snail.html
>>.
>
> Apparently the evolution of jaw asymmetry is convergent (synapomorphic
> homoplastic) in the two groups [see <
> http://naherpetology.org/pdf_files/400.pdf>]. As indicated by Aydin,
> sinistral snails seem to enjoy a selective advantage inasmuch as they are
> relatively refractory to predation by "right-handed" snakes. This may well
> account for the coevolution of chiral reversal in snail lineages (e.g.,
> Bradybaenidae, Camaenidae, Ariophantidae, Dyakiidae) that share their ranges
> with the snail-eating snakes in Asia.
>
> Speaking of synapomorphies homoplasties and coevolution, the Neotropical
> family Bulimulidae, separate (dextral) species of which are shown in the
> jaws of the two Sibon nebulata figured in Dan's report, have evolved three
> sinistral taxa (and I consider them independent lineages):
> Drymaeus inusitatus Fulton, 1900 Costa Rica and Panama.
> Drymaeus semimaculatus perversus Pilsbry, 1926, type locality Garachino
> Province, Panama. [nominotypical subspecies dextral]
> Drymaeus tropicalis (Morelet, 1849) type locality Campeche, Mexico, but my
> notes indicate that David Kirsh found a specimen on the grounds of Hotel
> Santa Maria de Ostuma, outside of Matagalpa, Nicaragua in August, 1983.
>
> Perhaps the same snake-snail selective forces are at play in Central America
> as in E, S, and SE Asia.
>
>
> At 10:48 AM 10/31/2012, David Campbell wrote:
>
> Other specialized snail-eating snakes (apparently subfamily
> Dipsadinae, though I find various classifications in a quick search,
> and the younger name Xenodontinae is sometimes used) range from Mexico
> to northern Argentina.  The genus Dipsas in these snakes is a senior
> homonym of an early unionoid bivalve name; the homonym was noticed
> early on and the name has not been significantly used in mollusks.
>
> On Tue, Oct 30, 2012 at 11:46 PM, David Kirsh <[log in to unmask]>
> wrote:
>> Friends,
>>
>> Please see the third item down by Dan Dourson about a snail-sucking snake:
>> http://www.mynewsletterbuilder.com/email/newsletter/1411504614



--
Dr. David Campbell
Visiting Professor
Department of Natural Sciences
Gardner-Webb University
Boiling Springs NC 28017

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