Data from: Consensus and confusion in Molluscan trees: evaluating morphological and molecular phylogenies

Mollusks are the most morphologically disparate living animal phylum, they
have diversified into all habitats, and have a deep fossil record.
Monophyly and identity of their eight living classes is undisputed, but
relationships between these groups and patterns of their early radiation
have remained elusive. Arguments about traditional morphological phylogeny
focus on a small number of topological concepts but often without regard
to proximity of the individual classes. In contrast, molecular studies
have proposed a number of radically different, inherently contradictory,
and controversial sister relationships. Here, we assembled a dataset of 42
unique published trees describing molluscan interrelationships. We used
these data to ask several questions about the state of resolution of
molluscan phylogeny compared to a null model of the variation possible in
random trees constructed from a monophyletic assemblage of eight
terminals. Although 27 different unique trees have been proposed from
morphological inference, the majority of these are not statistically
different from each other. Within the available molecular topologies, only
four studies to date have included the deep-sea class Monoplacophora; but
36.4% of all trees are not significantly different. We also present
supertrees derived from 2 data partitions and 3 methods, including all
available molecular molluscan phylogenies, which will form the basis for
future hypothesis testing. The supertrees presented here were not
constructed to provide yet another hypothesis of molluscan relationships,
but rather to algorithmically evaluate the relationships present in the
disparate published topologies. Based on the totality of available
evidence, certain patterns of relatedness among constituent taxa become
clear. The internodal distance is consistently short between a few taxon
pairs, particularly supporting the relatedness of Monoplacophora and the
chitons, Polyplacophora. Other taxon pairs are rarely or never found in
close proximity, such as the vermiform Caudofoveata and Bivalvia. Our
results have specific utility for guiding constructive research planning
in order to better test relationships in Mollusca as well as other
problematic groups. Taxa with consistently proximate relationships should
be the focus of a combined approach in a concerted assessment of potential
genetic and anatomical homology, while unequivocally distant taxa will
make the most constructive choices for exemplar selection in higher-level
phylogenomic analyses.