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19 December 2012

Common house plant threatened by climate change

Climate change

The purple flower African violet is a popular house plant in most of the world. Scientists from the University of Copenhagen have now revealed that the original wild population is seriously threatened by future climate change. The annual world trade value of the African violet is estimated to be more than 30 million US dollars.

 

Habitat for the African violet. Download free press picture. Photo credit: Steffen Brøgger-Jensen.

Habitat for the African violet. Download free press picture. Photo credit: Steffen Brøgger-Jensen.

The African violet, Saintpaulia H. Wendl., has been extensively bred and sold worldwide since a German baron brought home a few individuals from Tanzania more than a century ago.

However, the conditions for the wild populations have degenerated. This is shown by a new study from the University of Copenhagen in which the effects of future climate change on this species were simulated.

“Our models show that future climate change will cause the flower’s natural habitat to decrease in size. Additionally, we find that the plant has the highest levels of genetic variation in the worst affected areas. This is particularly unfortunate, as this genetic variation represents great potential for the plant industry. Also, this variation may teach us a great deal about what drives the formation of new species,” says Dimitar Dimitrov, who led the research at the Center for Macroecology, Evolution and Climate at the University of Copenhagen and is currently based at the Natural History Museum in Oslo.

An African Violet. Download free press picture. Photo credit: Steffen Brøgger-Jensen.

An African violet. Download free press picture. Photo credit: Steffen Brøgger-Jensen.

The uncertain future for the African violet is not improved by the fact that its natural range is in the Eastern Arc Mountains of Kenya and Tanzania, which are under further pressure from local land use change.

Furthermore, the plant only inhabits rocky streams in these tropical rainforests and therefore has limited opportunities for dispersal to new habitat. Associate professor Nikolaj Scharff from Center for Macroecology, Evolution and Climate adds:

“The African violet is just one of many species which will be affected by future climate change, but it is an example of the many plants and animals that are only found in very limited areas on the Earth, which makes them particularly vulnerable to human influence.”

The Eastern Arcs Mountains in Kenya and Tanzania. Download free press picture. Photo credit: Nikolaj Scharff.

The Eastern Arc Mountains of Kenya and Tanzania. Download free press picture. Photo credit: Nikolaj Scharff.

Despite its limitations, the plant has also proven to be surprisingly adaptable over a longer time span.

Dimitar Dimitrov and his colleagues have shown that Saintpaulia has undergone a lot of genetic differentiation in the lowlands within the last 5 million years, compared to other species of Saintpaulia that live higher up in the mountains. This implies that the development of new species is mainly driven by lowland populations. 

“If we want to protect the genetic variation of the African violets, we must focus our conservation efforts on the wild populations in the lowlands, where genetic differentiation seems to be high and new species apparently evolve. Otherwise, we risk ending up with an impoverished gene pool and thereby less opportunities to develop new Saintpaulia varieties for horticulture, and less wild genetic material to strengthen the Saintpaulia stock grown in households around the world,” says Dimitar Dimitrov.

The Saintpaulia species in the highlands have better prospects because they live in areas that are already protected, and are also less likely to be affected by climate change.

The article is published in PLOSone.
Dimitrov D, Nogués-Bravo D, Scharff N (2012) Why Do Tropical Mountains Support Exceptionally High Biodiversity? The Eastern Arc Mountains and the Drivers of Saintpaulia Diversity. PLoS ONE 7(11): e48908. doi:10.1371/journal.pone.0048908  

Contact:

Associate Professor Nikolaj Scharff
Center for Macroecology, Evolution and Climate
Natural History Museum of Denmark
The University of Copenhagen
phone: +45 3532 1107
mobile:  +45 42408088