Genetic diversity: The hidden face of biodiversity
Will future conservation policies have to take account of the genetic diversity within each species ? A large-scale study into plants found at high altitude throughout the Alps and the Carpathians, has enabled an international team of 15 laboratories to show that environments where genetic diversity of species is the highest are not necessarily those with the greatest number of species. The results, published on 25 September 2012 in Ecology Letters, open up new perspectives regarding strategies for the protection of biodiversity.
Since the Rio Conference in 1992, it has been accepted that biodiversity encompasses three interconnected levels: the diversity of ecosystems; that of the species making up the ecosystem; and the genetic diversity within each species. High genetic diversity is an advantage as it allows a species to adapt more readily, through evolution, to variations in its environment, including those brought about by climate change. However, only the 'ecosystem' and 'species' levels are considered when designing national parks and nature reserves. Genetic diversity is ignored, as it is difficult to assess and was thought to vary in accordance with species richness. In other words, the prevailing view was that the more species there were in an environment, the greater the genetic diversity within each species.
As part of the European IntraBioDiv project, an international consortium made up of 15 laboratories coordinated by the Laboratoire d'Écologie Alpine tested the hypothesis of co-variation between species richness and genetic diversity in high-mountain plants (those found more than 1500 meters above sea level). To compare the two levels of biodiversity, researchers mapped their distribution across the Alps and the Carpathians. To do this, they divided both mountain ranges into sectors, whose sides reached approximately 25 km. They then carried out field campaigns to count the number of species represented in each of the 561 study areas. A genetic analysis of over 14,000 specimens collected in the field was then performed in the laboratory.
The most significant result is that species richness and genetic diversity vary independently of each other, both in the Alps and in the Carpathians. For instance, in the Alps, the south-western region—located near the French-Italian border—is the richest in species, whereas the highest genetic diversity is found either in the Central Alps in Switzerland or in the North-east, in Austria.
Genetic diversity is still ignored when designing protected areas, despite its importance for the future of species. It would be advisable to take it into account when elaborating conservation strategies, in the same way as ecosystem and species diversity. The current revolution in DNA sequencing technology should soon authorize large-scale evaluation of such biodiversity within species, and lead to a better implementation of the Convention on Biological Diversity, which was adopted at the Earth Summit in Rio in 1992.