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Galapagos Tomatoes Show Signs of Reverse Evolution by Reviving Ancient Chemical Defenses
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Wild tomatoes on the younger islands of the Galรกpagos archipelago are displaying a rare phenomenon: reverse evolution. These plants are reverting to a more primitive genetic state, resurrecting ancient chemical defenses not seen in millions of years [1]. This unexpected development, detailed in *Nature Communications*, is challenging conventional views of evolution as a one-way process.
The Curious Case of Galapagos Tomatoes
these tomatoes, descendants of South American ancestors likely transported by birds, are producing a toxic molecular cocktail resembling compounds found in eggplant, not modern tomatoes.This “reverse evolution,” a term debated among evolutionary biologists,suggests that evolution might not always be a one-way street.
Did You Know? The Galรกpagos Islands are renowned for unique evolutionary adaptations, famously studied by Charles Darwin, but this case of reverse evolution adds a new layer to their biological importance.
Alkaloids: The Key to Unlocking the Past
The key to this chemical reversal lies in alkaloids, bitter molecules that act as natural pesticides. Tomatoes, potatoes, eggplants, and other nightshades produce these compounds to deter predators.While the Galรกpagos are known for their lack of animal predators, the plants still require defenses against insects and fungi.
Researchers at the University of California, Riverside, initiated this project to understand and control alkaloid production in crops, as high concentrations can be toxic to humans. Their findings revealed that the Galรกpagos tomatoes are producing “wrong” alkaloids, reminiscent of their early evolutionary days.
Geographic Distribution and Chemical Differences
Analyzing over 30 tomato samples from various locations, the team discovered a geographic pattern. Tomatoes on the eastern islands produced alkaloids similar to modern cultivated tomatoes. However, those on the western islands exhibited a different version, bearing the molecular fingerprint of eggplant relatives from millions of years ago.
This difference stems from stereochemistry, the arrangement of atoms in three-dimensional space. Molecules with the same atoms can behave differently based on their arrangement. By examining the enzymes responsible for assembling these alkaloids, the researchers found that changing just four amino acids in a single enzyme could switch the molecule’s structure from modern to ancestral.
pro Tip: Stereochemistry plays a crucial role in drug development
