With the participation of Colombian scientists, a study redrew the evolutionary tree of tiger-winged butterflies and revealed six new species.

With more than 400 species, the tigerwing and glasswing butterflies ( Ithomiine ), common in Central and South America, represent a significant proportion of the butterflies present in those regions. This makes them good ecological indicators in highly biodiverse environments such as the Amazon.

However, the similarity in the color patterns (suggesting toxicity in repelling birds) of the different varieties of these insects has posed a challenge for their study and monitoring.

In order to delve deeper into the genetic differences behind the small variations between species, new research has set out to rethink the family tree of this subfamily.

The research, published in the Proceedings of the National Academy of Sciences (PNAS), offers new insights into these butterflies, as well as into the factors involved in the rapid diversification of species and why some are more adaptable .

Among the findings, which help us understand how life has evolved so far and could provide clues as to how it might change in the future, is the fact that some of these butterflies can detect others of their own species through chemical signals, allowing them to recognize each other in areas where multiple species with identical appearance coexist.

Scientists have discovered that even the most closely related species of tigerwing butterflies produce different pheromones, indicating that they can recognize each other by these chemical signals. Since these butterflies look the same to warn predators that they are toxic, this mechanism allows them to find compatible mates.

The international team behind this study included experts from the Wellcome Sanger Institute, the Universidad Regional Amazónica Ikiam in Ecuador, the State University of Campinas in Brazil, the University of Cambridge, and other institutions.

Representing Colombia, Camilo Salazar , researcher and professor at the School of Science and Engineering at the Universidad del Rosario, and Nicol Rueda , a graduate of the PhD in Biomedical and Biological Sciences from the same institution, participated and collaborated in this multidisciplinary study.

Eva van der Heijden, lead author from the Wellcome Sanger Institute and the University of Cambridge, explained that this project arose because tigerwing butterflies are an incredibly adaptable group that has been valuable in ecological research for about 150 years.

"However, until now, we haven't had robust genetic resources to identify their species, which makes monitoring them difficult. With this new evolutionary tree and reference genomes, we hope to advance biodiversity and conservation research worldwide, and protect these butterflies and other insects that are key to the planet's ecosystems," the expert noted.

Caroline Bacquet, lead author from Ikiam University (Ecuador), explained that having the reference genomes of the genera Mechanitis and Melinaea allowed them to analyze how they have adapted to coexist with their glass-winged relatives. "They share color patterns to ward off predators, but they produce distinct pheromones that allow them to find mates . Now that we can distinguish between species, we can look for specific markers to track them in the field ," she indicated.

Among the characteristics of this group of butterflies that have caught the attention of scientists is their "rapid radiation," that is, the emergence of many new species from a common ancestor in a short period of time. Because they are so closely related, visual identification and tracking are difficult.

To address this problem, the international team sequenced the genomes of nearly all species belonging to two rapid radiations of the group, in order to redraw their evolutionary trees . Of these, ten species were selected and sequenced to "reference genome" quality, and their data are freely available to the scientific community.

Thanks to this genetic mapping, the team determined that six subspecies were more distinct from each other than previously thought, and are now considered new species. Furthermore, understanding them from a genomic perspective allows for identifying visual differences useful for monitoring them once they have been established as distinct species.

The researchers also analyzed the genomes for clues about the surprising speed with which these butterflies generate new species. While most butterflies have 31 chromosomes, in tiger butterflies this number varies between 13 and 28. Although they share most of their genes, they are organized differently on the chromosomes of each species, a phenomenon known as chromosome rearrangement.

These rearrangements have implications for reproduction. To produce sperm and eggs, chromosomes must align correctly. If two butterflies with different rearrangements mate, their offspring are usually sterile. Therefore, butterflies have developed a pheromone-based mechanism to detect compatible mates at the chromosomal level, thus avoiding infertile offspring.

The study suggests that this high degree of chromosomal rearrangement is key to the tiger wings' ability to rapidly form new species. Once a population changes its chromosome number and becomes a separate species, it can adapt more quickly to new altitudes or host plants. However, why they exhibit so many chromosomal changes is still unknown , a mystery that scientists continue to investigate.

Joana Meier, lead author from the Wellcome Sanger Institute, noted that amid the planet's extinction crisis, understanding how new species emerge—and why some evolve so rapidly—is key to preserving them. "Comparing butterflies that diversify rapidly with those that don't could reveal key drivers. This could help us prioritize species for conservation or identify useful genes for agriculture, medicine, or bioengineering. This research was made possible by global collaboration. We have only one planet, and we must work together to understand and protect it," she said.