“…The study of spread rates in heterogeneous environments for single-species models in continuous time began with the work by Shigesada et al (1986) and has since been extended to a variety of different situations, including two-dimensional domains (Kinezaki et al, 2003), competing species (Cruywagen et al, 1996), asymmetric dispersal , discrete-time equations (Kawasaki and Shigesada, 2007;Lutscher, 2008;Dewhirst and Lutscher, 2009), and more rigorous analytical results (Weinberger, 2002;Weinberger et al, 2008;Berestycki et al, 2005). Most of these modeling approaches represent landscape heterogeneity as two types of patches that are periodically alternating in space.…”