The Rapid Evolution of Giant Daisies
When Charles Darwin’s famous finches colonized the Galapagos Islands, they adapted to their new habitats by developing beaks particularly suited to feeding on the unique nuts, fruits, and insects that each island offered. But they are not the only organisms to have taken advantage of the opportunity of adaptive radiation. The genus of giant daisies Scalesia has also taken root there, and a new study published in Natural communications reveals how species have evolved to adapt to their new digs.
Just like Darwin’s finches, Scalesia plants adapted to fill various ecological niches once they arrived from mainland South America, from humid forests to dry lowlands. It didn’t take them long either, all living species of Scalesia appeared on the islands just 1 million years ago. “The appearance of different species varies greatly, from low shrubs to tall trees,” study co-author Michael D. Martin of the Norwegian University of Science and Technology said in a statement. “The most striking leaves are those that range from large and entire to small and deeply lobed. »
Read more: “Why is everything an orchid? »
These lobed leaves are thought to help cool plants by allowing better air circulation while reducing water loss. They really seem to be a godsend for Scalesia. According to the researchers’ genomic analysis, several species evolved the adaptation independently, but what surprised them most was how they evolved these structures: Each species used different genes belonging to the leaf development pathway to evolve the lobes.
“This provides a clear example of parallel evolution: nature arrives at the same solution several times, but through different genetic pathways,” explained Vanessa Bieker, co-author of the study. “Instead of being controlled by a single ‘master gene,’ evolution appears to rely on an entire network of interacting genes, modifying different components to produce similar results.”
And they also evolve. “Populations within the same species have large genetic differences and have been isolated from each other for long periods of time,” Martin said. “This means new species could be forming.”
Sometimes a change of scenery is all it takes to thrive.
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Main image: Michael Martin, NTNU University Museum
