The impact of anthropogenic disturbances on the genetic diversity of terrestrial species: a global meta-analysis

Human activities are primarily responsible for habitat loss and changes in natural environments around the world. It has been suggested that populations inhabiting human-modified landscapes are subject to reduced gene flow, inbreeding depression, and loss of alleles due to genetic drift. However, empirical evidence shows contradictory effects of anthropogenic disturbances on the genetic diversity of terrestrial species. We performed a meta-analysis of 61 studies that compared the genetic diversity of plant and/or animal populations in disturbed and preserved areas (317 paired comparisons) to investigate general responses to different disturbance type. We found significant negative effects of disturbance on genetic diversity (effect size: -0.45), in which the loss of structural connectivity was the most detrimental disturbance type. The choice of the genetic parameter has an influence on the detection of the effect (direction and magnitude), and consequently the studies using number of e...