Nature's gift for gardening may hold key to biodiversity

DNA analysis of wild evergreen rhododendrons in the Himalayas has suggested that hundreds of species of the plant could be derived from hybrids -- cross-breeds between different species.

Their findings may help explain the rich biodiversity of the natural world, as it shows how random pairings of wild plants millions of years ago has led to the development of hundreds of new species that exist today.

While scientists have long known that single species can derive from hybrid origins, this latest finding offers rare evidence that whole groups of species can be developed from a hybrid ancestor.

Scientists sampled the DNA of 79 species of rhododendron and used the results to analyse how each species was related.

They found that although most Himalayan rhododendrons were descended from the same ancestral line, three rogue species showed traces of a second, distantly related ancestor. This species, now extinct, may have arrived in the Himalayas within the last 10 million years, and interbred with species already there.

The discovery suggests that much of the diversity found in rhododendrons -- and perhaps many other species -- is a result of ancient cross-breeding, which has enabled a diverse range of offspring over many successive generations.

The joint study with Royal Botanic Garden Edinburgh, published in the Journal of Plant Systematics and Evolution, was supported by the Natural Environment Research Council.

Dr Richard Milne of the University of Edinburgh's School of Biological Sciences, who led the research, said: "Nature seems to be more creative than the most gifted of gardeners. Cross-breeding in the wild may have played a significant part in contributing to the wealth of species on Earth today -- but more work is needed to investigate the significance of this."