Molecular data indicate the protostome affinity of brachiopods

Area of Science:

• Zoology
• Evolutionary Biology
• Phylogenetics

Background:

• The phylogenetic placement of brachiopods has been contentious, with morphological data suggesting a sister relationship to deuterostomes.
• Molecular phylogenies, however, consistently group brachiopods within the protostomes, specifically the Lophotrochozoa.

Purpose of the Study:

• To review recent molecular data, particularly those with qualitative characteristics similar to morphological traits.
• To evaluate the evidence for brachiopod affinity within metazoan phylogeny.

Main Methods:

• Analysis of the complement of Hox genes across Metazoa for phylogenetic reconstruction.
• Examination of mitochondrial genome data, including gene rearrangements, as qualitative phylogenetic characters.

Main Results:

• Molecular data, including Hox gene complements and mitochondrial genome rearrangements, provide strong evidence for brachiopod affiliation with protostomes.
• Brachiopods are phylogenetically placed within the Lophotrochozoa, alongside groups like annelids and molluscs.

Conclusions:

• The molecular evidence strongly supports the protostome (Lophotrochozoan) affinity of brachiopods.
• A reinterpretation of brachiopod morphological and developmental characters is necessary to align with molecular findings.
• Further research into brachiopod morphology is recommended to reconcile conflicting data.