A family of mysterious plants that can be traced back to Gondwana
The strange tropical plants belonging to the Corsiaceae family first emerged millions of years ago on the supercontinent of Gondwana. That is what Leiden University researcher Constantijn Mennes concludes in an article in the Journal of Biogeography.
Scientists still know very little about the Corsiaceae family. Until now, researchers even doubted whether or not the various genera were really part of the same family. Constantijn Mennes, who also works at the Naturalis Biodiversity Center, studied the DNA of the various genera and reached the conclusion that they are in fact part of the same family, despite a number of external differences. His analysis also revealed that their common ancestor originated in Gondwana 30 million years ago, one of the two supercontinents that eventually broke apart to form today’s continents.
The plants of the Corsiaceae family are common on both sides of the Pacific, including in South America, Australia and Papua New Guinea. ‘That’s why scientists have suspected a common link to Gondwana for quite a long time,’ Mennes explains. ‘That supercontinent broke apart millions of years ago, eventually forming the continents as we know them today.’
Mennes discovered that the various genera are more than 30 million years old. ‘That suggests that their common ancestor is even older and existed around the time that Gondwana began to break up,’ Mennes explains. ‘It’s an indication that the Corsiaceae family did in fact come into existence in that supercontinent. The huge distances between the current genera can thus be attributed to the breaking up of Gondwana.’
DNA analysis has revealed that the Corsiaceae family is also related to the lily. Mennes: ‘They can best be described as distant cousins, and there is little about their appearance that suggests any relation at all. Millions of years of evolution and adaptation to environments have induced major differences. But even now we can still see subtle similarities, for instance, in the flower petals and in the pollen.’
The Corsiaceae family is a special group of plants that can be found among the lowest vegetation in tropical forests. Unlike most other plants they don't have any chloroplasts, the organelles in cells that enable photosynthesis: the process that turns sunlight and carbon dioxide into oxygen and carbohydrate molecules. Like most animals, these plants are heterotroph instead, meaning they get their energy from other organisms (in this case from fungi). Chloroplasts are also necessary to make plants and leaves green, which the Corsiaceae plants therefore are not. Instead, they slightly resemble orchids.
(6 March 2015)