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Butterflies show that new species can evolve from hybridization

A study led by Harvard University has provided a fresh perspective on evolutionary processes, particularly in how species intermingle and evolve. The experts have found compelling evidence that hybridization can lead to the formation of entirely new species, challenging traditional views of evolution as a neatly branching tree.

Evolution of Heliconius butterflies 

Revisiting a fascinating observation first made by naturalist Henry Walter Bates in 1861 and shared with Charles Darwin, the scientists examined the evolution of the Heliconius butterflies of the Amazon. 

Bates famously described these butterflies as a peek into nature’s workshop for creating new species. Now, the researchers provided direct evidence of this phenomenon by documenting the evolution of a new butterfly species through hybridization.

Hybridization and new species

The study focused on Heliconius butterflies, shedding new light on how a hybridization event from 180,000 years ago between Heliconius melpomene and an ancestor of today’s Heliconius pardalinus gave rise to a third species, Heliconius elevatus

This new species is not just a blend of its progenitors but has distinct ecological and physiological traits, such as unique preferences for caterpillar host plants and specific adult characteristics like male sex pheromones, wing color patterns, and mate selection.

Hybridization and evolution

“Historically hybridization was thought of as a bad thing that was not particularly important when it came to evolution,” said Neil Rosser, an associate in entomology at the Museum of Comparative Zoology and a former postdoctoral fellow at Harvard. “But what genomic data have shown is that in fact hybridization among species is widespread.”

This discovery not only challenges the traditional concept that species are distinct, non-overlapping units, but also highlights the fluidity with which genetic material is exchanged in nature. “A lot of species are not intact units,” Rosser said. “They’re quite leaky, and they’re exchanging genetic material.”

Evolution of completely new lineages 

The research also raises important questions about how new species emerge from the intermingling of existing ones. “So the species that are evolving are constantly exchanging genes, and the consequence of this is that it can actually trigger the evolution of completely new lineages,” Rosser explained.

“Normally, species are thought to be reproductively isolated. They can’t produce hybrids that are reproductively fertile,” added co-author James Mallet, a professor of organismic and evolutionary biology at Harvard. Thus, although there is now evidence of hybridization between species, it was still difficult to confirm that this hybridization is, in some way, involved in speciation.

Fluid nature of species boundaries 

The implications of this study extend beyond academic circles. Understanding the fluid nature of species boundaries is crucial for conservation efforts, particularly in biodiversity hotspots like the Amazon. It also has potential applications in studying disease vectors, such as mosquitoes that carry malaria, and their inter-species interactions.

This paradigm shift in understanding hybridization and evolution marks a significant advance, suggesting that the interplay of genetic material across species boundaries can play a pivotal role in the emergence of new species.

More about Heliconius butterflies 

Heliconius butterflies, also known as longwing butterflies, are a diverse and colorful group found primarily in tropical regions, particularly in Central and South America. They are notable for their striking patterns and vibrant colors, which serve as a form of defense through mimicry and warning signals. Heliconius butterflies exhibit a variety of interesting behaviors and adaptations:

Müllerian mimicry

Heliconius butterflies are famous for their participation in Müllerian mimicry, where multiple species share similar warning coloration to protect against predators, as the colors signal toxicity.

Diet and lifespan of Heliconius butterflies

Unlike most butterflies that sip nectar, Heliconius butterflies also feed on pollen, which is rich in proteins and extends their lifespan significantly, often living several months rather than the usual weeks that most butterflies survive.

Reproduction and habitat

They have unique reproductive behaviors, including the use of pheromones and lekking (males display in groups). They often return to the same spot each night, showing high site fidelity.

Conservation status

While some species are abundant and widespread, others are endangered and face threats from habitat destruction due to logging and agriculture.

Role in ecosystems

Heliconius butterflies are important pollinators in their ecosystems, helping to maintain the health and diversity of tropical forests.

The study is published in the journal Nature.


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