Genetic diversity of A ndean P olylepis ( R osaceae) woodlands and inferences regarding their fragmentation history

There is a long‐standing debate on whether the occurrence of the iconic high‐ A ndes P olylepis woodlands as small and isolated fragments is of natural or anthropogenic origin. We make inferences regarding the fragmentation history based on both a new population genetic study on P . besseri and a synthesis of available studies on the population genetics of P olylepis woodlands. We infer the timing of the main woodland fragmentation event by analysing: (1) the remaining levels of population genetic diversity and the relation to population size; (2) among‐population genetic differentiation; and (3) the difference in genetic diversity between the offspring and adult generation. We retrieved seven publications on the population genetics of five P olylepis spp. We did not find a relationship between population size and genetic diversity, and genetic differentiation was low compared with that reported for similar plant species. These findings do not support a history of long‐term fragmentation. The offspring showed a loss of genetic diversity and increasing differentiation compared with adults, suggesting that the main habitat fragmentation event is of relatively recent origin. For P . besseri , no significant differences were found between the adult and offspring genetic variation. We discuss the conservation and restoration consequences for this important high‐ A ndean genus. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society , 2013, 172 , 544–554.