Animal evolution. The end of the intermediate taxa?

Area of Science:

• Zoology
• Evolutionary Biology
• Molecular Phylogenetics

Background:

• A comprehensive, reliable global animal phylogeny has been lacking for decades.
• Molecular phylogeny advancements are rapidly providing new evolutionary frameworks.
• Traditional phylogenies relied on anatomical data, often leading to debated classifications.

Purpose of the Study:

• To establish a robust, global animal phylogeny using molecular data.
• To re-evaluate the evolution of animal body plans.
• To reconcile molecular findings with existing anatomical data and address controversies.

Main Methods:

• Analysis of molecular data to construct phylogenetic trees.
• Purging potential artefacts from molecular phylogenies.
• Comparison of molecular-derived trees with traditional, anatomically-based phylogenies.

Main Results:

• Molecular phylogenies confirm some traditional classifications.
• Strikingly, two superphyla (acoelomates and pseudocoelomates) previously considered intermediate grades have disappeared.
• A simplified global tree of metazoans with few major branches is emerging.

Conclusions:

• The new molecular phylogeny provides a reliable reference for animal evolution.
• The simplified tree explains conserved developmental genes in bilaterians.
• It suggests a novel interpretation of the 'Cambrian explosion' and animal diversification.