Over the past decade, several studies and reviews have documented the apparent resilience of widespread tree species to the population genetic consequences of habitat fragmentation and disturbance (for example, Lowe et al., 2005; Lowe, 2005; Kramer et al., 2008; Bacles and Jump, 2010). Classically, under conservation genetic principles, decreases in population size and density of trees, caused by habitat fragmentation and disturbance activities such as logging, are expected to reduce genetic diversity, increase genetic differentiation and potentially increase inbreeding (Lowe et al., 2004). Yet a large number of forest tree species are able to ameliorate these population genetic pressures through a variety of mechanisms. The first is through extensive gene flow via pollen and/or seed (in many cases over 10 s of km; e.g. White et al., 2002; Bacles et al., 2005), which can maintain connectivity even in highly fragmented and degraded landscapes where trees persist at very low densities in matrices of varied land use (for example, Breed et al., 2011; Lander et al., 2011). The second is due to the long-lived nature of trees and the existence of overlapping generations on single sites that serves to retard the loss of genetic diversity (for example, Lowe et al., 2005; Petit and Hampe, 2006; Bacles and Jump, 2010; Davies et al., 2010). Thirdly, flexible mating systems in some species can circumvent self-incompatibility to allow selfed progeny to form (Ward et al., 2005), particularly when faced with an Allee effect (lack of compatible mates within a landscape).
Lowe, A. J., Cavers, S., Boshier, D., Breed, M. F., & Hollingsworth, P. M. (2015). The resilience of forest fragmentation genetics--no longer a paradox--we were just looking in the wrong place. Heredity, 115(2), 97-99. https://doi.org/10.1038/hdy.2015.40