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Recently, the article "High level of novelty under the hood of convergent evolution" was published in the journal "Science", the result of the hard work of a team of researchers led by Dr. Riccardo Papa —professor of biology at the University of Puerto Rico, Río Piedras Campus— and which includes Steven M. Van Belleghem (postdoc), Carolina Concha (postdoc), Angelo A. Ruggieri (PhD student of Dr. Papa's laboratory), Edgardo Santiago Rivera (master's student, graduate of Papa's laboratory), Silvia Planas (SGF Technician) and Yadira Ortiz-Ruiz (Laboratory technician of Dr. Papa's laboratory). All students are part of the Department of Biology of the UPR of Rio Piedras.

This article —very novel and proposing concepts that had never been said before, otherwise it would not be published in "Science"— demonstrates for the first time that homology at the level of morphological traits has been oversimplified and that, if the molecular architecture of the functional part of the genome that regulates gene expression (epigenetics) on development is carefully observed, It will be found that similar traits are actually very different or divergent. This study shows large-scale evolutionary patterns that recently describe the genotype-to-phenotype map in development. The work demonstrates that while development is about editing genes in space and time, evolution can recreate identical morphologies in completely different lineages with alternative regulatory architectures.

"This tells us clearly that evolution is not deterministic but allows us to recreate identical traits in very different ways," explains Dr. Papa. We can now say with certainty that different butterfly species separated by 11 million years of divergence achieved identical wing color patterns by using the same set of genes in alternate ways at different times and spaces.

"This is an important discovery as it implies that there are endless possibilities for life to produce identical outcomes and is not limited to a single way of creating similar solutions. Such general findings give a very different and novel interpretation of the biological similarities of homologous structures, as they may have a very distinct epigenomic architecture under apparent morphological similarity."

Dr. Papa adds that "this also has strong implications for medical research, as it suggests being very careful when comparing the molecular architecture of two similar characters or tissues in different organisms."

"After all," he points out, "in the evolutionary history of each species, their relative genomes expand, contract, mutate and reorganize in very unique ways that imply a strong drift in the level of development. Our results represent evolution in a novel way and explain the logic behind the incredible biodiversity we observe in the world. This is a message of hope that suggests that nature and evolution can generate life forms in infinite possible forms. The beauty of life and its manifestation are free from extreme restrictions."

 This project has been made possible by a $4 million grant obtained by Dr. Papa and his team in 2018 from the National Science Foundation (NSF). The proposal —in which Dr. Papa is the principal investigator— is called "Genomic logic underlying adaptive morphological divergence", and is carried out in butterflies, since they are insects with a great diversity of phenotypes, mostly with tropical butterflies of the genera Heliconius, which also includes the zebra butterfly (Heliconius charithonia) of Puerto Rico. Support for this project was also provided by Puerto Rico Science, Technology & Research Triust and the NIH PRINBRE. 

"This work represents the effort of many students of the Department of Biology of the UPR in Rio Piedras and shows that in Puerto Rico and in the UPR it has a program of excellence and that we produce science of very high impact and quality despite all the challenges," says Dr. Papa. "It is important that the people of Puerto Rico can be informed about achievements like this, since it is the public university in the country."

- Written by the University of Puerto Rico.