 MUSSELp Evolution, for our purposes, refers to the relationships among taxa. This is in weak contrast to MUSSELp Taxonomy, which we use to characterize problems of nomenclature and species diversity. The real distinction between these two angles of the MUSSEL Project is the method of analysis. Our evolution studies are phylogenetic analyses aimed at discovering relationships and describing diversity above the species level. Taxonomy refers to database issues, managing the voluminous data on alpha-taxonomy and subsequent revisions. The division is somewhat artificial, but while we continue to wear two different hats, we will continue to organize our MUSSELp revision of the Unionoida according to the various analyses that we undertake and the nature of the data.
We advocate a cladistic (under construction) approach for testing hypotheses of freshwater mussel relationships. Such an approach allows us to marry classification to evolutionary theory, and that is an obvious improvement over the authoritarian essays that formed the basis for classification in the past.
 Our goal is to provide a detailed discussion of the patterns of freshwater mussel evolution (under construction) and to those patterns to test hypotheses of macroevolutionary processes. What are the interrelationships of freshwater mussels? And, what is the data behind our current understanding? What areas are most in need of additional research? For example, with a robust phylogeny for freshwater mussels, we can explore the history of larval evolution among freshwater mussels.
For systematic malacology to be scientific, it must be transparent and repeatable. This web site is also the repository for the data matrices used in various analyses. If you would like to share your matrix and make this a community effort, send an email to Daniel Graf.
For the non-systematist, the valuable front end that will be provided by this work is a stable classification. At this time, what we can do is identify which parts are currently stable and which still need more work. There are six families of freshwater mussels, and they are generally grouped into two superfamilies, although the grouping has varied historically. The relationships of the North American freshwater mussels are the best understood in the world, but we can hypothesize, based upon the available evidence, a classification for the whole order.
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