Twenty-first-century climate changes are expected to have effect on the tree of life, as it is envisaged that many species will become affected. If losses are not randomly distributed across the tree of life, climate change could lead to a disproportionate loss of evolutionary history. However, in Europe, climate change will affect the different plant and animal groups (genera, families, orders) in about the same degree.
There are hardly any genera or families which are threatened in their entirety to go extinct. This keeps the so-called ‘phylogenetic diversity’ in Europe high. Researchers conclude this in Nature this week, based on a survey of the environmental requirements of 1280 European plant species, 340 bird species and 140 mammals.
Phylogenetic diversity is a measure of biodiversity, which was introduced in 1992 by Australian Daniel Faith. It is more subtle than a simple species list and takes into account the degree of relatedness between plants or animals. For example, when in a given area 25 unrelated different bird species breed, the biodiversity is valued more highly than when there would have been 25 closely related endemic bird species.
The researchers determined the relationship between the hundreds of plants and animals by DNA analysis. The environmental requirements (minimum temperature, precipitation, etc.) of the plant and animal species were derived from their current distribution. Then, for two emission scenarios (including an extremely unfavorable IPCC scenario) using known climate models it was determined how the species’ geographical distribution would be changed in 2020, 2050 and 2080. This showed that species vulnerability to climate change clusters weakly across phylogenies. The impact on biodiversity, e.g. phylogenetic extinction, is not greater than when the climatic influence had been totally random. This is because vulnerable species have neither fewer nor closer relatives than the remaining taxonomic branches of the tree of life.
All in all European biodiversity loss will suffer far less damage than is suggested by researchers who used a simple species lists. Reductions in phylogenetic diversity will be greater in southern Europe, and gains are expected in regions of high latitude or altitude. Unfortunately, losses will not be compensated by gains and the tree of life faces a trend towards homogenization across the continent. (Sources, NRC, 19.02.2011; Nature, 16.02.2011)