Large-scale longitudinal gradients of genetic diversity: a meta-analysis across six phyla in the Mediterranean basins

Predicting patterns of variation in biodiversity across the globe is a fundamental issue in ecology and evolution. Diversity within species, that is, genetic diversity, is of prime importance for understanding past and present evolutionary patterns, and highlighting areas where conservation might be a priority. However, most studies on spatial patterns of genetic diversity have not considered longitude as a potentially important ecological driver of these patterns. Therefore, we carried out a meta-analysis to examine the longitudinal patterns of genetic diversity in the Mediterranean Basin. Using published literature and a systematic review/meta-analysis framework, we collected data on the genetic diversity of species whose populations occur in the Mediterranean basin. We then calculated a coefficient of correlation between within‐population genetic diversity indices and longitude, and estimated the role of biological, ecological, biogeographic, and marker type factors on the strength and magnitude of this correlation in six phylla. The results of this study were published in the paper titled Large‐scale longitudinal gradients of genetic diversity: a meta‐analysis across six phyla in the Mediterranean basin (Conord et al. 2012).