Related Experiment Video
Updated: Dec 14, 2025

A Whole Mount In Situ Hybridization Method for the Gastropod Mollusc Lymnaea stagnalis
Published on: March 15, 2016
The genetic factors of bilaterian evolution
Peter Heger1, Wen Zheng1, Anna Rottmann1
1Institute for Genetics, Cologne Biocenter, University of Cologne, Cologne, Germany.
Abstract:
The Cambrian explosion was a unique animal radiation ~540 million years ago that produced the full range of body plans across bilaterians. The genetic mechanisms underlying these events are unknown, leaving a fundamental question in evolutionary biology unanswered. Using large-scale comparative genomics and advanced orthology evaluation techniques, we identified 157 bilaterian-specific genes. They include the entire Nodal pathway, a key regulator of mesoderm development and left-right axis specification; components for nervous system development, including a suite of G-protein-coupled receptors that control physiology and behaviour, the Robo-Slit midline repulsion system, and the neurotrophin signalling system; a high number of zinc finger transcription factors; and novel factors that previously escaped attention. Contradicting the current view, our study reveals that genes with bilaterian origin are robustly associated with key features in extant bilaterians, suggesting a causal relationship.
Related Concept Videos
Genetics of Speciation
Convergent Evolution
Chromosomal Theory of Inheritance
The Evidence for Evolution
Background and Environment Affect Phenotype
An example of how genetic background affects phenotype can be seen in horses. The Extension gene in horses is responsible for their coat color. A wild-type gene (EE) produces black pigment in the coat, while a mutant gene (ee) produces red pigment. A...
Gene Duplication and Divergence
The duplicated copies of the gene are called Paralogs. Paralogs with similar sequences and functions form a gene family. Across several species, a large number of gene families are...

