Spatial prioritization of amphibian intraspecific genetic diversity: The need of accounting for palaeoenvironmental legacies

Biodiversity is a multifaceted concept, and conservation actions must consider all levels of biodiversity. Spatial prioritization of conservation efforts usually targets species diversity, while consideration of intraspecific genetic diversity is frequently hampered by the lack of data. Here, we combined genetic data (mtDNA) from multiple amphibian species and measures of environmental stability to i) identify the overall drivers of present-day intraspecific genetic diversity (nucleotide diversity and phylogenetic originality); ii) define priority areas for the conservation of genetic diversity, and iii) assess the surrogacy value of species diversity for genetic diversity in Italy and nearby areas. We tested for potential environmental predictors of genetic diversity and originality by fitting spatially-explicit Bayesian mixed models, and used species-specific predictions to generate spatial prioritizations of intraspecific genetic diversity. Present-day phylogenetic originality was positively correlated with climate and habitat stability since the Last Glacial Maximum (pseudo-R2 : 0.61), while the same set of predictors had limited explanatory power for nucleotide diversity (pseudo-R2 : 0.15). The spatial pattern of originality remarkably matched previously identified refugial areas for plants, as well as the distribution of some microendemic species. Prioritizations targeting phylogenetic originality showed that high conservation performance might be achieved with relatively low effort. However, the surrogacy between genetic and species-diversity was limited, implying that larger efforts would be needed to preserve genetic diversity while taking species diversity into account. Our study provides an example of how spatially-explicit approaches allow prioritization of conservation efforts accounting for both species and intraspecific genetic diversity, thus improving the long-term conservation of biodiversity.