The secrets of the “giant daisies” in Galapagos revealed
These plants are an exception to the “rule of progression”.
The study was conducted by researchers from Spain, Ecuador and the United States. Reference photo / RJB-CSIC
October 5, 2020, 9:04 am
Researchers from Spain, Ecuador and the United States have revealed the secrets of the “explosive” diversification of “giant Darwin daisies” in the Galapagos Islands.
As reported today by the Royal Botanical Garden of Madrid -under the Spanish Higher Council for Scientific Research-, it is the first evolutionary study with genetic data of the “Scalesia” genus, and the researchers have also verified that these plants are an exception to the ” rule of progression “, according to which species and lineages of ancient origin are expected to occupy older islands.
The conclusions of the study have been published in the journal Current Biology, explained today the Botanist, who recalled that the “evolutionary radiations” in oceanic islands have fascinated biologists since Darwin carried out the exploration of the Galapagos archipelago.
These “radiations” are groups of closely related species that have originated very quickly, even in an “explosive” way (in “only” a few hundred thousand years) from a single ancestral species that arrived on the islands.
Specifically, radiation occurring in oceanic archipelagos (usually volcanic) have been considered ideal systems for investigating the action of evolution since Darwin exposed his theory.
The Spanish Botanical Garden specified that radiation in volcanic islands usually entails an accelerated evolution as a consequence of the great ecological diversity, which is called “adaptive radiation”.
The best known example of radiation on islands is located in the animal kingdom and, specifically, in the so-called Galapagos finches, also known as “Darwin’s finches”.
But now scientists have published the results of a pioneering study on all species of the genus “Scalesia”, also known as “Darwin’s giant daisies”, one of the most iconic plants on these islands.
The results of this research reveal that the “Scalesia lineage split from its closest relatives on the continent (South America) about 3 million years ago.
However, the current fifteen “Scalesia” species, all unique to the Galapagos Islands, would have diversified rapidly from a common ancestor in “more recent” times, probably in the last million years.
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