Research suggests the criteria scientists use to assess a if plant species is at risk of extinction may need revising, if conservation efforts are to save endangered plants - News

by Simon Levey
24 May 2011

New research suggests that scientists may need to revise the criteria they use to assess whether a plant species is at risk of going extinct, if they are to concentrate their conservation efforts on the plants most in need.

According to widely-used criteria, known at the Red List, a species is considered to be 'at risk of extinction' if it inhabits a limited geographical area and has a small population size. Now, thanks to a new analysis of a range of plant specimens from South Africa and the UK, biologists have shown that these criteria also wrongly categorise plant species as 'at risk' when they are simply newly arrived in an area.

The research has been led by Professor Vincent Savolainen who holds a joint post in the Department of Life Sciences at Imperial College London and Kew Gardens, and Dr Jonathan Davies from the Department of Biology at McGill University in Canada. It is published today in the journal PLoS Biology.

Dr Davies said: "Reducing rates of extinction represents one of the greatest ecological challenges of our time, but identifying which species are most at risk can be difficult."

For more than 40 years, the International Union for Conservation of Nature (IUCN) has published the Red List of Threatened Species describing the conservation status of various species of animals. They are now also including plants in their lists and the picture they present is dramatic. According to recent estimates, around 20 per cent of flowering plants are currently at risk of extinction – although the exact number is unknown since such a small proportion of plant species has even been measured.

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The results of the study also suggest that a plant species' risk of extinction is most closely related to the age of the species. This is different to the factors that are thought to put animal species most at risk and contrary to existing theories. Characteristics currently thought to increase a species’ risk of extinction include traits like having a large body that takes a long time to reach sexual maturity, such as elephants, or a tendency to bear one offspring at a time with a long time interval between births, as pandas do.

"In plants, we show that the processes of extinction and speciation (the evolutionary process by which new species arise) are linked – seemingly the most vulnerable species are often the youngest. Young species may appear at high risk of extinction simply because their populations have not yet had time to grow and spread. However, it is also possible that some plant species might be doomed to extinction from their very inception," Davies said.

Deciding which species should have the highest priority for conservation is a difficult  process and these findings are likely to be controversial. Co-author Professor Savolainen, said: "Our results challenge the application of the same sets of threat criteria across living organisms – plant versus animals – and across regions – biodiversity hotspots in South Africa versus temperate countries such as the UK.

"The IUCN is doing an important job, but we may need to think of ways to fine tune the implementation of Red List criteria for rapid assessments of threat – a daunting task that might prove even more pressing given the changes we see in our global environment."

The research was funded by The Darwin Initiative, The Royal Society, the South African National Research Foundation, the Leverhulme Trust, the Natural Environment Research Council and the European Research Council.