             to model dispersal histories first presented by van Etten and
             Hijmans (2010) &lt;doi:10.1371/journal.pone.0012060&gt;. Least-cost
             distances as well as more complex distances based on (constrained)
             random walks can be calculated. The distances implemented in 
             the package are used in geographical genetics, accessibility 
             indicators, and may also have applications in other fields of
             geospatial analysis.">
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