and gene duplication events that took place over hundreds of millions of years have set the stage for tissue-specific gene expression, as per a recent study. These ‘copy-paste’ errors have enabled animals to retain one copy of their genome or genes for essential functions, while the duplicate copy can be utilized for evolutionary innovation. Such events, occurring at different scales, have been a consistent feature throughout the evolutionary tree of bilaterians, leading to the development of various traits and behaviors, including insect flight, octopus camouflage, and human cognition.
A series of whole genomeA recent study published in the journal Nature Ecology and Evolution suggests that gene duplication events dating back hundreds of millions of years have played a crucial role in tissue-specific gene expression. These “copy paste” errors have allowed animals to retain one copy of their genome or genes for essential functions, while the duplicate copy has served as a source for evolutionary innovation. These events have occurred at different scales throughout the evolutionary tree of bilaterian organisms, leading to the development of diverse traits and behaviors such as insect flight, octopus camouflage, and human cognition.The first appearance of a significant creature occurred 600 million years ago. Despite its unimpressive appearance compared to modern standards, this animal had distinct front and back, top and bottom features. This was a major development at the time, establishing the basic body plan that most complex animals, including humans, would later inherit.
This inconspicuous animal lived in the ancient seas of Earth, possibly moving along the seafloor. It was the common ancestor of bilaterians, a large group of animals that includes vertebrates (fish, amphibians, reptiles, birds, and mammals) and invertebrates (insects, arthropods, and more).
Bilaterians, including humans, sharks, mayflies, centipedes, and octopuses, can trace more than 7,000 groups of genes back to their last common ancestor, according to a study of 20 different bilaterian species. Researchers at the Centre for Genomic Regulation (CRG) in Barcelona made this discovery, and it is published in the journal Nature Ecology and Evolution.
Surprisingly, the study revealed that about half of these ancestral genes have been repurposed by animals for specific parts of the body, particularly in the brain and reproductive systems. This includes pods, molluscs, worms, echinoderms, and many other organisms.”
ve tissues. The discoveries are unexpected because ancient, conserved genes typically have crucial, essential roles that are necessary in many areas of the body.
Upon closer examination, the researchers discovered a series of fortunate ‘copy paste’ errors that occurred during bilateral evolution. For instance, there was a significant moment in the early history of vertebrates. A group of tissue-specific genes emerged at the same time as two whole genome duplication events. This allowed animals to retain one copy for fundamental functions, while the second copy could be utilized for evolutionary innovation. Events like these, occurring at different stages of evolution, have played a crucial role in the development and diversification of species.
Multiple duplication events, occurring at varying degrees of scale, were constantly happening throughout the evolutionary tree of bilaterian organisms.
“Our genetic code is comparable to a large collection of recipes that can be altered to create or modify tissues and organs. If you were to accidentally end up with two identical copies of a recipe for paella, you could still retain and enjoy the original while evolution modifies the extra copy to produce risotto instead. Now, imagine the entire recipe book being duplicated — not just once, but twice — and the endless possibilities it presents for evolution. The effects of these events, which occurred hundreds of millions of years ago, continue to persist in most complex animals today,” explains Federica Mantica.The writer of the article and a scientist at the Centre for Genomic Regulation (CRG) in Barcelona.
The study’s authors discovered numerous instances of new, tissue-specific functions resulting from the specialization of these ancient genes. For instance, the TESMIN and tomb genes, which originated from the same ancestor, independently evolved to serve specialized roles in the testis in both vertebrates and insects. Their significance is underscored by the fact that issues with these genes can disrupt sperm production, impacting fertility in both mice and fruit flies.
The specializationThe evolution of ancestral genes also set the groundwork for the development of intricate nervous systems. For instance, in vertebrates, the scientists discovered genes that are crucial for the creation of myelin sheaths around nerve cells, which are necessary for rapid nerve signal transmission. Additionally, in humans, they pinpointed FGF17, a gene believed to play a significant role in preserving cognitive functions as individuals age.
Meanwhile, in insects, certain genes became specialized in muscles and in the epidermis for cuticle formation, aiding in their ability to fly. On the other hand, in the skin of octopuses, different genes became specialized for perceiving light stimuli, contributing to their unique capabilities.Our research shows that octopuses have the ability to change color, blend in with their surroundings, and communicate with each other. By examining how species have evolved at the tissue level, we found that changes in gene expression in different parts of the body have been instrumental in creating new and unique characteristics in animals. Essentially, when genes become active in specific tissues, it can lead to the development of new physical traits or abilities, ultimately contributing to the evolution of animals. This challenges our understanding of the roles and functions of genes, demonstrating that genes essential for survival have been preserved and utilized in new and unexpected ways.Millions of years of evolution can lead to the acquisition of new functions, demonstrating the delicate balance between preserving vital roles and exploring new paths. This conclusion comes from ICREA Research Professor Manuel Irimia, who is a co-author of the paper and a researcher at the Centre for Genomic Regulation.
Journal Reference:
- Federica Mantica, Luis P. Iñiguez, Yamile Marquez, Jon Permanyer, Antonio Torres-Mendez, Josefa Cruz, Xavier Franch-Marro, Frank Tulenko, Demian Burguera, Stephanie Bertrand, Toby Doyle, Marcela Nouzova, Peter D. Currie, Fernando G. Noriega, Hector Escriva, and M. Tereza Martin-Blazquez.Here is the HTML reformatted in a more readable way:
Ina Arnone, Caroline B. Albertin, Karl R. Wotton, Isabel Almudi, David Martin, and Manuel Irimia. “Evolution of tissue-specific expression of ancestral genes across vertebrates and insects”. Nature Ecology & Evolution, 2024; DOI: 10.1038/s41559-024-02398-5