Integrative Taxonomy Uncovers Cryptic Daisy Species

Some plants are so similar to one another that the classification methods developed by 18th-century scientist Carl Linnaeus are no longer sufficient for distinguishing between species. In a recent thesis from the University of Gothenburg, researchers used modern DNA technology to identify entirely new species of daisies.

There are currently an estimated 8.7 million distinct species on Earth, with approximately 2.2 million located in the oceans. Many species can be identified classically, based on their physical traits, or morphology. Botanists and zoologists have used DNA sequencing to improve species identification for more than a decade. So far, scientists have chosen a single place in the DNA that is characteristic of the species, although this can be erroneous.

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.”

Zaynab Shaik, Study Author and PhD Student, University of Gothenburg

Daisies in South Africa

Zaynab Shaik's research focuses on 66 accepted daisy species found in her native South Africa's Cape Province. The daisies are well-known, with the first species described in 1753, however there is one group of daisies in the area that botanists have found difficult to identify. The plants are ‘cryptic’ because they appear identical, having matching leaves and flowers, growth style, and distribution. However, they differ greatly genetically.

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

Mistaken for Other Species

Zaynab’s DNA analysis of these cryptic species led to the discovery of four additional species.

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

Zaynab Shaik’s method for identifying species is known as integrative taxonomy. It entails complementing traditional observations of plant appearance and growth habits with DNA sequencing in a laboratory. Together, these strategies improve the comprehension of the boundaries between distinct species. Scientists utilizing this technology will find new species at a faster rate than previously believed.

She concluded, “In the Cape, it has been thought that only 1 percent of 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.”