New species of daisies discovered with refined DNA technology

Sometimes plants are so similar to each other that the methods developed by the scientist Carl Linnaeus of the 18th century to identify species are not enough. In a thesis from the University of Gothenburg, completely new species of daisies were discovered when analyzed with modern DNA technology.

There are currently estimated to be about 8.7 million different species on Earth, of which about 2.2 million are found in the oceans. Many species can be identified in the classic way, by their physical characteristicsits morphology.

For more than a decade, botanists and zoologists have also been using DNA sequencing to more accurately identify species. Until now, scientists have chosen a single site in the DNA that is typical of the species, but this sometimes risks being wrong.

“There are times when different plant species are difficult to characterize from a small DNA sequence. But now DNA sequencing has taken several steps forward and we have been able to identify completely new species by analyzing a larger part of the genome,” he says Zaynab Shaikh. , author of a doctoral thesis at the University of Gothenburg.

Daisies in South Africa

Shaik focused on a group of 66 accepted species of daisies, which grow in the Cape Province of his native South Africa. Daisies are well known, with the first species described in 1753, but there is a group of daisies in the area that have been difficult for botanists to identify. The plants are “cryptic”, they look identical, with similar leaves and flowers, and have the same growth habit and similar distribution. However, they differ significantly genetically.

“It is important that we have a better understanding of the relationships between plants and biodiversity on Earth. It is easy to imagine how wrong it can be if you discover that a plant is suitable for use as a base in a drug , and then pick another, similar, species instead, which do not have the same properties at all,” says Shaik.

Mistaken for other species

Zaynab’s DNA analysis of these cryptic species they resulted in the discovery of four new species.

“When I am asked about it, there is a bit of an anti-climax when explaining that it is not that I found a new daisy in a remote location which no one has seen before. But these were admired for a long time, but they were mistaken for another species.”

The method Shaik uses to identify species is called integrative taxonomy. It involves integrating traditional observations of plant appearance and growth habit with DNA sequencing in a laboratory. Together, these methods provide a better understanding of the boundaries between different species. Scientists using this method will discover new species at a higher rate than previously expected.

“In the Cape, it was thought that only 1% of the biodiversity remains to be discovered. My results suggest that it could be much more than that. And the same should reasonably apply to other areas of the globe,” says Shaik .