Understanding the impact of historical and demographic processes on
genetic variation is essential for devising conservation strategies and
predicting responses to climate change. Recolonizations after
Pleistocene glaciations and population's positions within species ranges
are expected to leave distinct genetic signatures. However, the general
applicability of these patterns and relative importance of historical
and demographic factors remains unknown. Here, we analysed the
distribution of genetic variation in 91 native species of North American
plants by coupling microsatellite data and Species Distribution
Modelling. We tested the contributions of historical climatic shifts and
the central-marginal hypothesis on genetic diversity and structure.
Decreased diversity was found with increased distance from potential
glacial refugia, coinciding with the expected make-up of postglacially
colonised localities. At the range periphery, lower genetic diversity,
higher inbreeding levels and genetic differentiation were reported,
following the assumptions of the central-marginal hypothesis. History
and demography were found to have approximately equal importance in
shaping genetic variation.