Paper on known unknowns published
Bieler, Mikkelsen and Giribet of our group have just published a new paper entitiled Bivalvia — a discussion of known unknowns (American Malacological Bulletin, 31(1): 123-133).
Bivalves share many of the “deeper” questions with the other molluscan groups – issues such as their origin and sister-group relationships within the Mollusca, and their suitability to explore molecular data in a “known” fossil framework. Other questions are more specific to bivalves, a group that radiated so successfully and nowadays predominantly specializes as infaunal and sessile epifaunal suspension feeders. This paper highlights and explores unanswered questions, from the seemingly trivial and mundane (e.g., how many species are actually out there?), to addressing enigmatic clades about which we know extremely little besides their shells, to macroevolutionary questions that could best be addressed by bivalve-based data. Fast-developing molecular approaches, including the first genome-level and transcriptomic data, a resurgence of detailed morphological and soft-anatomical research, and a renewed focus on Bivalvia by biological and paleontological workers provide us with an opportunity to address such issues. Coordination of efforts – and reciprocal illumination – across traditional disciplinary boundaries will be key factors in such endeavors.
Mapping mollusks: Researchers use genetic tools to complete family tree
Using genetic tools, researchers at Harvard and collaborating institutions have completed the most comprehensive evolutionary tree ever produced for mollusks. More...
[Phys.org (Nov 2, 2011)]
BivAToL presentations at the 77th Annual Meeting of the American Malacological Society
From July 23-29, 2011, BivAToL participants attended the 77th Annual Meeting of the American Malacological Society at Duquesne University in Pittsburg, Pennsylvania. Paula Mikkelsen (PRI) presented the first paper in the keynote symposium, “Mollusks: The Great Unanswered Questions,” entitled “Marine Bivalvia — a Discussion of Known Unknowns,” coauthored by Rudiger Bieler. Dan Graf also presented in this symposium with his invited paper entitled “Global Freshwater Bivalve Diversity.” Ilya Temkin presented a paper in the “Cretaceous and Cenozoic Molluscan Paleontology Symposium,” coauthored with Ellen Strong, entitled “Evolution of the alimentary system in heterodont bivalves,” about his excellent anatomical work on bivalve stomachs. John M. Pfeiffer III, a University of Alabama student under Dan Graf, presented a poster entitled “Polyphyly of the Freshwater Mussel Genus Lamprotula (Mollusca: Bivalvia: Unionidae)” and won the Best Student Poster Award at the meeting. The complete meeting program can be accessed online (PDF format). Paula has been a member of this scientific society since 1978.
New publication on structure and symbionts of Anodontia ovum
Ball, A. D., K. Purdy, E. A. Glover and J. D. Taylor. 2009. Ctenidial structure and three bacterial symbiont morphotypes in Anodontia (Euanodontia) ovum (Reeve, 1850) from the Great Barrier Reef, Australia (Bivalvia: Lucinidae). Journal of Molluscan Studies 75: 175-185.
The structure of the ctenidia of the Indo-West Paciﬁc chemosymbiotic lucinid bivalve Anodontia(Euanodontia) ovum was investigated by electron microscopy. Ctenidial ﬁlaments are similar in general morphology to those described from other Lucinidae, with a ciliated zone, a short intermediary zone and a thick abfrontal zone composed largely of bacteriocytes separated by narrow intercalary cells. The bacteriocyte zones of adjacent ﬁlaments are fused in the distal part to form short cylindrical channels. The apices of intercalary cells project as cytoplasmic protrusions in the form of spiky tufts, with sheets and tendrils spreading over adjacent bacteriocytes. Compared with other lucinids A. ovum lacks abfrontal granule cells, mucocytes are infrequent and the bacteriocyte channels are short. Three morphotypes of symbiotic bacteria were detected, associated with the bacteriocyte zone of the ctenidial ﬁlaments: (1) all bacteriocytes contained abundant bacteria 3 – 5 mm long and 0.5 – 1.0 mm wide, enclosed in single vacuoles; (2) some bacteriocytes possessed spherical vesicles enclosing masses of smaller rod-shaped bacteria c. 1.0 mm long; (3) probable spirochaete bacteria, 8 – 10 mm long and 0.3 mm wide, were abundant within the apical cytoplasmic protrusions of the intercalary cells. Preliminary molecular analysis using 16S rRNA gene sequences has so far identiﬁed only one bacterial symbiont, from the gamma division of Proteobacteria grouping in a cluster of symbiotic thiotrophs. This symbiont of A. ovum is closely similar to a symbiont previously reported from the western Atlantic lucinid Anodontia schrammi (originally cited as A. philippiana).
New publication on Cyrenoididae
John D. Taylor, Emily A. Glover, Suzanne T. Williams. 2009. Phylogenetic position of the bivalve family Cyrenoididae — removal from (and further dismantling of) the superfamily Lucinoidea. The Nautilus 123(1):9-13.
A molecular analysis using sequences from 18S and 28S rRNA genes of the brackish and freshwater bivalve Cyrenoida floridana, in conjunction with a wide range of other heterodont bivalves, demonstrated a close relationship with the families Corbiculidae and Glauconomidae and distant from the Luci noidea, where the Cyrenoididae had been usually classified. Based on this result it is proposed that the Cyrenoididae be removed from the Lucinoidea, which, for living taxa, now includes only the family Lucinidae.
Follow our expedition to Moreton Bay, Australia
Several members of the BivAToL team were recently in Moreton Bay, Australia on an intensive bivalve collection trip. From digging in the mud flats to deep-water dredging, they were trying to collect many of the species on our list that will be analyzed in our quest for the bivalve phylogenetic tree.
For more information:
- Video clips and dispatches from the field in the PRI blog
- The full story at Expeditions@Field Museum
New publication on Lasaea adansoniiA new publication examines the larval biology of the brooding bivalve Lasaea adansonii, one of Bivatol’s targeted species. Andreas Altnöder and Gerhard Haszprunar (Bivatol collaborator) of the University of Munich, Germany, used transmission and scanning electron microscopy, fluorescent staining, and computer-assisted 3D reconstruction to show that Lasaea is a true direct developer, with few truly larval features in its young. The paper was published in April 2008 in the Journal of Morphology, volume 269, pages 762-774.
AToL meeting in New Orleans (Mar 7 - 9, 2008)
Six members of the Bivatol Project (Rüdiger Bieler, Gonzalo Giribet, Paula Mikkelsen, Tim Collins, Ellen Strong, and Brian Gollands) attended the biennial AToL Principal Investigator meeting at the Hilton St. Charles in New Orleans, March 7-9, 2008, hosted by Hank Bart of Tulane University (Bony Fishes AToL).
Over 100 participants from all current AToL projects attended themeeting to hear summary reports, and discuss methods and resultsincluding what's working and what's not in the various projects. Thenine new projects for 2006-2007 gave brief slide presentations, andolder AToLs provided posters. NSF-AToL Program Officer Pat Herendeenwas in attendance and provided valuable administrative advice on manypoints. Special topic sessions included social networking andcollaborative tools, supertree approaches, building ontologies,extacting data from digital libraries, advances in phylogeneticanalysis of molecular data, morphological image databases andphyloinformatics tools, whole-genome phylogenetic analyses,internationalizing AToL research, building careers through publishedAToL research, and AToL in education and broader impact areas. Mostinformative during the discussions was a comparison of the advantagesof MorphoBank, MorphBank, and Morphster software packages, withdevelopers present in the room. The Encyclopedia of Life andBiodiversity Heritage Project also gave presentations. The meeting wasa great "jump start" for all Bivatol participants, bringing new ideasand enthusiasm to continue our progress. NSF hosts this type of meetingfor AToL participants every two years; the 2010 meeting will be inChicago.