Temporal variation in genetic diversity during an outbreak of Oligoryzomys longicaudatus (Rodentia, Sigmodontinae) in a temperate forest of southern Chile

► Results did not show deviations of the mutation-drift and demographic equilibrium. ► Breakdown phase did not cause a bottleneck over post-outbreak populations. ► There was a change of haplotype composition during outbreak and post-outbreak. ► Post-outbreak reduction variability may be due to emigration or local extinction. ► Gene flow is the main mechanism underlying changes in genetic variability at VNP.