A phylogenetic backbone for Bivalvia: an RNA-seq approach.

Area of Science:

• * Zoology and evolutionary biology.
• * Marine biology and invertebrate paleontology.

Background:

• * Bivalves are a diverse invertebrate group with significant ecological and economic importance.
• * Despite extensive study, their deep phylogenetic relationships remain poorly understood, hindering their use as a model for macroevolutionary research.
• * A robust phylogeny is crucial for understanding bivalve evolution and their role in aquatic ecosystems.

Purpose of the Study:

• * To construct the first robust phylogenomic backbone for Bivalvia.
• * To resolve long-standing questions regarding the monophyly and interrelationships of major bivalve lineages.
• * To demonstrate the utility of phylogenomic approaches for resolving evolutionary histories in bivalves.

Main Methods:

• * Employed a phylogenomic approach using novel transcriptomic data from 31 bivalve species.
• * Integrated new RNA-seq data with publicly available genomic and transcriptomic data from other bivalves and outgroups.
• * Analyzed hundreds of genes to reconstruct the evolutionary history of Bivalvia.

Main Results:

• * Generated a well-resolved and robust phylogenetic tree for Bivalvia, delineating all major lineages.
• * Resolved the monophyly of Protobranchia and Heterodonta, clarifying their evolutionary placement.
• * Established the phylogenetic positions of key groups including Palaeoheterodonta, Archiheterodonta, and Anomalodesmata.

Conclusions:

• * The study provides a fully resolved phylogenetic backbone for Bivalvia, settling critical evolutionary questions.
• * Phylogenomic methods using extensive gene data are effective for resolving deep evolutionary relationships in bivalves.
• * This resolved phylogeny enhances the potential of bivalves as a model system for macroevolutionary studies.