A hidden genetic trick is helping fish evolve into entirely new species—right before our eyes. Meet the ‘supergenes’ that are supercharging evolution in Africa’s Lake Malawi.
Key Points at a Glance
- Scientists discovered chromosomal inversions in cichlid fish that act as evolutionary accelerators
- These DNA flips keep beneficial gene sets together, forming ‘supergenes’
- Supergenes help fish adapt to specific habitats and avoid blending with other species
- Some inversions also function as sex chromosomes, potentially influencing speciation
- The findings offer a broader insight into how biodiversity emerges across life on Earth
Why are there so many species in the world—and how do they emerge so quickly? A new study sheds light on this age-old question by zooming in on a single lake in East Africa, where an explosion of evolution has taken place among its finned residents.
In Lake Malawi, over 800 species of cichlid fish have evolved from a single ancestor in an evolutionary blink—less than the time it took for humans and chimpanzees to diverge. This stunning diversity has baffled scientists for years. Now, researchers from the Universities of Cambridge and Antwerp may have found a clue: a phenomenon hidden deep in the genome, known as chromosomal inversions.
These inversions are sections of DNA that have ‘flipped’ direction, disrupting the normal shuffling process that happens during reproduction. When this recombination is blocked, clusters of genes—especially those key to survival—stay together. This genetic tight-knit group is called a ‘supergene’, and it acts like an evolutionary power pack.
“It’s like having a toolbox where all your best tools are glued together—ready to be handed down intact,” said Moritz Blumer from Cambridge’s Department of Genetics and first author of the study, published in Science.
By examining DNA from over 1,300 cichlids, the team found these supergenes on five different chromosomes. Not only do they preserve adaptive traits—like vision for different water depths or pressure resistance—but they also help keep closely related species genetically distinct, even when they live side by side in the same sandy lake zones.
What’s more, some inversions double as sex chromosomes, influencing whether a fish becomes male or female. This dual role could be a driving force behind the birth of new species, offering evolutionary advantages and barriers all in one genetic package.
“These supergenes give species the freedom to experiment with new forms and behaviors, while still holding on to what works,” explained co-senior author Professor Richard Durbin. “It’s a genetic strategy for innovation without chaos.”
Intriguingly, these chromosomal inversions aren’t unique to fish. They’ve also been found in butterflies, birds—and even humans. Their role in evolution may be far more universal than previously thought.
“By understanding how supergenes evolve and spread, we’re getting closer to solving one of science’s biggest puzzles: how life became so rich, complex, and beautiful,” said study co-leader Hennes Svardal.
In the shimmering waters of Lake Malawi, evolution may not be just a matter of chance—but of cleverly conserved genetic structures guiding life’s endless forms most wonderful.
Source: University of Cambridge
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