In this project, a large team of investigators will resolve evolutionary relationships within the bivalves (clams, oysters, mussels, scallops, etc.). Bivalves are a diverse and familiar group of mollusks with an old and well-preserved fossil record. Bivalves have important ecological roles in marine and freshwater ecosystems, and economic roles including fisheries, the ornament industry, and health sciences. Bivalves are the second largest class of living mollusks, which in turn constitute the second largest animal phylum and the largest in the marine realm.

The evolutionary history and relationships of bivalves will be investigated through a fresh look at bivalve anatomy in combination with study of selected DNA markers for the same species investigated morphologically. This international team of investigators will assemble morphological and molecular phylogenetic data at levels of detail never before attempted.

Outreach activities will engage various audiences in the project’s results and in evolutionary science as a whole. This project presents an excellent opportunity for outreach to communicate the concepts of evolution, and this team of researchers is well-placed to accomplish this. Museum exhibits and instructional materials using bivalves will be developed for K-12 teachers and their students, post-secondary teachers and their students, and the general public, in the form of a traveling exhibit (“Evolution on the Half-Shell”) and associated teaching materials.


Why Bivalvia?
Importance & Diversity

From the many aspects that one could consider in studying bivalve diversity, 3 are most relevant to this project.

  1. Bivalves are an ancient group, diversified from other molluscan lineages by the Cambrian, and therefore have a deep evolutionary history.
  2. Bivalves show special diversity in marine and freshwater ecosystems, where they play important ecological roles.
  3. Bivalves are of economic importance to humans, including fisheries, the ornament industry, and health sciences. Diversity-wise, bivalves—with 20,000-30,000 living species—constitute the second largest class of Mollusca, which in turn is the second largest animal phylum and the largest in the marine realm. Because bivalves are familiar (and as “seashells”, popular) objects, they also are an excellent group for engaging the public on biodiversity issues.




  1. Reconstruct the phylogenetic relationships for representatives of all ca. 100 bivalve families based on a combination of shell-morphological, soft-anatomical, and molecular sequence data by using an exemplar approach. Test monophyly of each proposed superfamily and (where feasible) family.
  2. Explore new or previously underutilized anatomical and ultrastructural character systems (features of the alimentary tract, ultrastructure of sperm and mantle), and new genetic markers (a new suite of nuclear protein-coding genes never used previously for bivalves).
  3. Estimate the time of origin of the major bivalve clades based on molecular sequence and fossil data.


  1. Train undergraduates, graduate students, and postdocs in modern anatomical, molecular, and systematic methods, with special attention to minority involvement by providing hands-on training via field and lab workshops.
  2. Develop and provide Internet resources for K-16 teachers in the form of online lesson materials and lab practicals focusing on molluscan diversity and evolution.
  3. Engage the general public in issues of molluscan diversity and evolution through a traveling exhibition (with online component) featuring relevant issues such as fisheries and aquaculture, mollusks and human disease, economic and ecological impact of bivalve invasions and extinctions, and ecological aspects of bivalves as biofiltrators.


Project funding

Funding for the BivAToL project was awarded in 2007 to Dr. Rüdiger Bieler of the Field Museum of Natural History (Chicago, Illinois), Dr. Gonzalo Giribet of the Museum of Comparative Zoology (Harvard University, Cambridge, Massachusetts), Dr. Paula M. Mikkelsen of the Paleontological Research Institution (Ithaca, New York), and collaborators as part of a multi-year, multi-institutional effort to assemble the Bivalve Tree of Life.