Conserving the functional and phylogenetic trees of life of European tetrapods

Abstract

Protected areas (PAs) are pivotal tools for biodiversity conservation on the Earth. Europe has had an extensive protection system since Natura 2000 areas were created in parallel with traditional parks and reserves. However, the extent to which this system covers not only taxonomic diversity but also other biodiversity facets, such as evolutionary history and functional diversity, has never been evaluated. Using high-resolution distribution data of all European tetrapods together with dated molecular phylogenies and detailed trait information, we first tested whether the existing European protection system effectively covers all species and in particular, those with the highest evolutionary or functional distinctiveness. We then tested the ability of PAs to protect the entire tetrapod phylogenetic and functional trees of life by mapping species' target achievements along the internal branches of these two trees. We found that the current system is adequately representative in terms of the evolutionary history of amphibians while it fails for the rest. However, the most functionally distinct species were better represented than they would be under random conservation efforts. These results imply better protection of the tetrapod functional tree of life, which could help to ensure long-term functioning of the ecosystem, potentially at the expense of conserving evolutionary history.

Keywords: endemics; evolutionary distinctiveness; functional distinctiveness; gap analysis; protected areas.

Figure 1.

Species range covered by the European PA system according to species range size. Each species is represented by a dot. Species range size is expressed in log scale. Species' target achievement is shown with a colour gradient from red to blue (low to high species target achievement).

Figure 2.

Evolutionary distinctiveness according to species' target achievements. The black line represents the ordinary least square (OLS) regression line, while the upper and lower dashed lines represent the 0.1 and 0.9 quantile regressions. The evolutionary distinctiveness of each species is the median over the 100 maximum-likelihood trees. The black line corresponds to the spline regression between evolutionary distinctiveness and species' target achievement for illustrative purposes.

Figure 3.

Functional distinctiveness according to species' target achievements. Relationships between species' target achievements and the functional distinctiveness of the four groups. The black line represents the OLS regression line, while the upper and lower dashed lines represent the 0.1 and 0.9 quantile regressions.

Figure 4.

Evolutionary and functional distinctiveness relationship and species' target achievements. Relationships between evolutionary and functional distinctiveness for each species group. Dot size corresponds to species' target achievements (low: less than 25%; high: more than 75%; and medium: between 25 and 75%). The evolutionary distinctiveness of each species is the median over the 100 maximum-likelihood trees.

Figure 5.

Species' target achievements mapped onto the phylogenetic tree of each group. For the four groups (a–d), species' target achievements were mapped onto the tree. For each internal branch, the maximum target achievement for the descendant was taken. Colours from red to blue indicate lowest to highest CE. The subplot in the corner represents the CE under random species' target achievements along the tree (9999 repeats). Red indicates the level of significance at 0.05 and 95%. The black line indicates the observed CE. The black asterisk close to the black line indicates significance at 0.05 (one sided). The trees and null models have been carried out over one randomly taken tree from the 100 maximum-likelihood trees for each group.

Figure 6.

Species' target achievements mapped onto the functional tree of each group. For the four groups, species' target achievements were mapped onto the tree. For each internal branch, the maximum target achievement for the descendant was taken. Colours from red to blue indicate lowest to highest CE. The subplot in the corner represents the CE under random species' target achievements along the tree (9999 repeats). Red indicates the level of significance at 0.05 and 95%. The black line indicates the observed CE. The black asterisk close to the black line indicates significance at 0.05 (one sided). The trees and null models have been carried out over one randomly taken tree from the 100 maximum-likelihood trees for each group.