Recent Publications

Research related apple snail topics (like relations between species, article discussions, apple snail ecology, anatomy, genetic info etc.).
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Recent Publications

Postby khayes on Thu Aug 27, 2009 9:23 pm

Hi All,
Below are the abstracts from two recent publications that may be of interest to some of you. If you would like pdf copies of either or both publications feel free to email me.

Hayes, K.A., R.H. Cowie, A. Jørgensen, R. Schultheiß, C. Albrecht and S.C. Thiengo. 2009. Molluscan models in evolutionary biology: Apple snails (Gastropoda: Ampullariidae) as a system for addressing fundamental questions. American Malacological Bulletin 27(1/2):47-58.

Abstract:
Molluscs constitute the second largest phylum in terms of the number of described species and possess a wide array of characteristics and adaptations for living in marine, terrestrial, and freshwater habitats. They are morphologically diverse and appear in the fossil record as far back as the early Cambrian (~560 mybp). Despite their high diversity and long evolutionary history, molluscs are often underused as models for the study of general aspects of evolutionary biology. Freshwater snails in the family Ampullariidae have a global tropical and subtropical distribution and high diversity with more than 150 species in nine currently recognized genera, making them an ideal group to address questions of historical biogeography and some of the underlying mechanisms of speciation. They exhibit a wide range of morphological, behavioral, and physiological adaptations that have probably played a role in the processes of diversification. Here we review some of the salient aspects of ampullariid evolution and present some early results from ongoing research in order to illustrate the excellent opportunity that this group provides as a system for addressing numerous questions in evolutionary biology, particularly with regard to the generation of biodiversity and its distribution around the globe. Specifically, we suggest that ampullariids have great potential to inform (1) biogeography, both on a global scale and a smaller intra-continental scale, (2) speciation and the generation of biodiversity, through analysis of trophic relations and habitat partitioning, and addressing issues such as Rapoport’s Rule and the latitudinal biodiversity gradient, and (3) the evolution of physiological and behavioral adaptations. Also, a number of species in the family have become highly successful invasives, providing unintentional experiments that may offer insights into rapid evolutionary changes that often accompany introductions, as well as illuminating invasion biology in general.

Hayes, K.A., S.C. Thiengo and R.H. Cowie. 2009. A global phylogeny of apple snails: Gondwanan origin, generic relationships and the influence of outgroup choice (Caenogastropoda: Ampullariidae). Biological Journal of the Linnean Society 98:61-76.

Abstract: Apple snails (Ampullariidae) are a diverse family of pantropical freshwater snails and an important evolutionary link to the common ancestor of the largest group of living gastropods, the Caenogastropoda. A clear understanding of relationships within the Ampullariidae, and identification of their sister taxon, is therefore important for
interpreting gastropod evolution in general. Unfortunately, the overall pattern has been clouded by confused systematics within the family and equivocal results regarding the family’s sister group relationships. To clarify the relationships among ampullariid genera and to evaluate the influence of including or excluding possible sister taxa, we used data from five genes, three nuclear and two mitochondrial, from representatives of all nine extant ampullariid genera, and species of Viviparidae, Cyclophoridae, and Campanilidae, to reconstruct the phylogeny of apple snails, and determine their affinities to these possible sister groups. The results obtained indicate that the Old and New World ampullariids are reciprocally monophyletic with probable Gondwanan origins. All four Old World genera, Afropomus, Saulea, Pila, and Lanistes, were recovered as monophyletic, but only Asolene, Felipponea,and Pomella were monophyletic among the five New World genera, with Marisa paraphyletic and Pomacea polyphyletic. Estimates of divergence times among New World taxa suggest that diversification began shortly after the separation of Africa and South America and has probably been influenced by hydrogeological events over the last 90 Myr. The sister group of the Ampullariidae remains unresolved, but analyses omitting certain outgroup taxa suggest the need for dense taxonomic sampling to increase phylogenetic accuracy within the ingroup. The results obtained also indicate that defining the sister group of the Ampullariidae and clarifying relationships among basal caenogastropods will require increased taxon sampling within these four families, and synthesis of both morphological and molecular data.
Last edited by khayes on Fri Aug 28, 2009 7:47 pm, edited 1 time in total.
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Re: Recent Publications

Postby Lupin on Fri Aug 28, 2009 10:56 am

Hi Mr. Ken,

I like your abstract although it's a bit deep in scientific terms. I had to do internet search for the meanings of the following.
Monophyletic
In phylogenetics, a group is monophyletic (Greek: of one stem) if all organisms in that group are known to have developed from a common ancestral form, and all descendants of that form are included in the group. A taxonomic group that contain organisms but not their common ancestor is called polyphyletic, and a group that contain some but not all descendants of the most recent common ancestor is called paraphyletic.

For example, all organisms in the genus Homo are believed to have come from the same ancestral form in the family Hominidae, and no other descendants are known. Thus the genus Homo is monophyletic. If, on the other hand, it were discovered that Homo habilis had developed from a different ancestor than Homo sapiens, and this ancestor was not included in the genus, then the genus would be polyphyletic. Since biologists by and large prefer groups to be monophyletic, in this case they would likely either split the genus or broaden it to include the additional forms.

It should be noted that evolutionary taxonomists use the term holophyletic for the sort of groups discussed here, whereby monophyly includes both holophyly and paraphyly.

Paraphyletic
In phylogenetics, a grouping of organisms is said to be paraphyletic (Greek para = near and phyle = race) if all the members of the group have a common ancestor, but the group does not include all the descendants of the most recent common ancestor of all group members.

Groups which include all the descendants of the most recent common ancestor are commonly termed monophyletic or holophyletic. The former is more common, but sometimes paraphyletic groups are also considered monophyletic, in which case the latter is used.

Many of the older classifications contain paraphyletic groups, especially the traditional 2-6 kingdom systems and the classic division of the vertebrates. For example, the class Reptilia as traditionally defined is paraphyletic because that class does not include two groups of its descendants, birds (in class Aves, birds), and mammals (in class Mammalia). Paraphyletic groups are often erected on the basis of plesiomorphies (ancestral similarities) instead of upon apomorphies (derived similarities).

In most cladistics-based schools of taxonomy, the existence of paraphyletic groups in a classification are regarded as errors. Some groups in currently accepted taxonomies may later turn out to be paraphyletic, in which case the classifications may be revised to eliminate them. Some, however, feel that having paraphyletic groups is an acceptable sacrifice if it makes the taxonomy more understandable. Others argue that paraphyletic groups are necessary to have a comprehensive classification including extinct groups, since each species, genus, and so forth necessarily originates from part of another. It has been suggested that paraphyletic groups should be allowed but clearly marked as such, for instance in the form Reptilia*.

Polyphyletic
In biology, a taxon is polyphyletic if it is descended from more than one root form (in Greek poly = many and phyletic = racial).

Scientific classification aims to group species together such that every group is descended from a single common ancestor, and the elimination of groups that are found to be polyphyletic is therefore a common goal, and is often the stimulus for major revisions of the classification schemes.

Opinions differ as to whether valid groups need to contain all the descendants of a common ancestors. Groups that do so are called monophyletic, and according to cladistics it should be the aim of classification to ensure that all groups have this property. However, many other taxonomists would argue that there is a valid place for groups that are paraphyletic, i.e. contain only the descendants of a common ancestor, but do not contain all its descendants.



What's your email address? I am interested to get the pdf files for further reading. :yes: Thanks for posting this!
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Re: Recent Publications

Postby pbgroupie on Fri Aug 28, 2009 2:27 pm

Ken, I think you and Donya were cut from the same bolt of cloth. You have to be a scientist to understand most of it (even though Lupin broke some of the terms down). I did get the general drift and I'm so happy you posted it here. I always like hearing about your findings and your results. Please don't forget to send a copy of your research to Stijn. He's another one who can understand what you are trying to do and your results and, with your permission and proper credit of course, it might get posted somewhere on the site as well. Just a thought!

Lupin, you can find his e-mail addy by clicking on the little envelope under Ken's stats.
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Re: Recent Publications

Postby Donya on Fri Aug 28, 2009 6:17 pm

Awesome! :dance:

I was just able to download the full text pdfs for both (althought he first one is "Molluscan models in evolutionary biology: Apple snails (Gastropoda: Ampullariidae as a system for addressing fundamental questions*"? The title differed a bit, but all other citation points matched). I'm not sure if others will be able to get them that way; I accessed the journal sites from Yale's network, which seems to give access to most journals automatically. At any rate, those articles will most certainly be a pleasant break from trying to troubleshoot my department's Linux networks before the term starts.
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Re: Recent Publications

Postby khayes on Fri Aug 28, 2009 7:49 pm

Oops, Thanks Donya, that was an old title - glad you caught that! Fixed.

Most major universities will have access to these journals, but for anyone that doesn't have access and would like them, just let me know. Due to copyright issues and such I can't just put them up on the web, but anyone that wants a copy can just pm me with your email and I'll provide them for you.

Cheers,
Ken
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Re: Recent Publications

Postby Lupin on Sat Aug 29, 2009 12:29 pm

pbgroupie wrote:Lupin, you can find his e-mail addy by clicking on the little envelope under Ken's stats.

I think it was hidden since I tried looking for it, Suz. I thought I may have a blonde moment again. :err:

PM sent with my email in it, Ken. :dance:
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