Taxonomic and phylogenetic biases in translocated angiosperm plant species across European countries

Conservation translocations are a well-known conservation tool used to reverse the effects of local population extinctions and restore ecosystems. Compared with mammals and birds, plants are underrepresented in translocation programs, and little is known about the potential taxonomic and phylogenetic biases of plant translocation efforts. We aimed to assess how translocated plant species may contribute to the conservation of phylogenetic diversity (PD) among European countries. Focusing on angiosperms across 4 European countries with well-documented flora and comprehensive sampling of translocated plant species, we determined whether species translocations were related to species conservation status with binomial generalized linear mixed models with threat status as a binary response variable. Then, we evaluated the taxonomic and phylogenetic biases of translocated plant species relative to national floras based on PD and evolutionary distinctiveness (ED). To evaluate PD and ED, we constructed null models to assess the deviation of observed values from those expected under a scenario in which translocated species were randomly sampled from the species pool of national floras in each country. Although most species lacked conservation status assessment, plant translocations mainly targeted species with high extinction risk at national, European, and global scales. Although plant orders with a higher representativeness of translocated species also tended to have a higher representativeness of native species, the probability of species being translocated varied significantly across plant order, suggesting a significant taxonomic bias. Based on null models and considering all countries, PD and mean ED of translocated plants were higher than expected by chance in most countries. These results suggest that although translocation programs were implemented independently across countries, the diversity of translocated plant species is relevant to conserving PD from national to continental scales and restoring evolutionarily distinct species when these species succeed. We argue that PD indicators should be incorporated into translocation planning to restore target species' evolutionary trajectories and to contribute to conservation of PD.