Investigating the Bivalve Tree of Life – an exemplar-based approach combining molecular and novel morphological characters

• DOI: 10.1071/is13010
• Publication Date: 2014-03-20T03:41:14Z
• Authors: Rüdiger Bieler; Paula M. Mikkelsen; Timothy M. Collins; Emily A. Glover; Vanessa L. González; Daniel L. Graf; Elizabeth M. Harper; John Healy; Gisele Y. Kawauchi; Prashant P. Sharma; Sid Staubach; Ellen E. Strong; John D. Taylor; Ilya Tëmkin; John D. Zardus; Stephanie Clark; Alejandra Guzmán; Erin McIntyre; Paul Sharp; Gonzalo Giribet
• Keywords: Monophyly; Maximum parsimony; Molecular Phylogenetics

To re-evaluate the relationships of major bivalve lineages, we amassed detailed morpho-anatomical, ultrastructural and molecular sequence data for a targeted selection exemplar bivalves spanning phylogenetic diversity class. We included 103 species (up to five markers) also analysed subset taxa with four additional nuclear protein-encoding genes. Novel as well historically employed morphological characters were explored, systematically disassembled widely used descriptors such gill stomach ‘types’. Phylogenetic analyses, conducted using parsimony direct optimisation probabilistic methods on static alignments (maximum likelihood Bayesian inference) data, both alone in combination characters, offer robust test relationships. A calibrated phylogeny provided insights into tempo evolution. Finally, an analysis informativeness showed that sperm ultrastructure are among best features diagnose clades, followed by shell, including its microstructure. Our study found support monophyly most broadly recognised higher taxa, although was not uniform Protobranchia. However, protobranchiate gills best-supported hypothesis incremental and/or data. Autobranchia, Pteriomorphia, Heteroconchia, Palaeoheterodonta, Archiheterodonta, Euheterodonta, Anomalodesmata Imparidentia new clade ( = Euheterodonta excluding Anomalodesmata) recovered across irrespective treatment or analytical framework. Another supported our analyses but formally literature includes Palaeoheterodonta which emerged under multiple conditions. The origin diversification each these clades is Cambrian Ordovician, except diverged from during Cambrian, diversified Mesozoic. Although radiation some lineages shifted towards Palaeozoic (Pteriomorphia, Anomalodesmata), presented gap between (Archiheterodonta, Unionida), steady through classification system six monophyletic proposed comprise modern Bivalvia: Protobranchia, Imparidentia.