In reading this book, you have observed that the spatial data used in landscape ecology come from many sources and in many forms. For many organisms, these data take the form of presence or absence at a location, or numbers of individuals at that same location. For species such as trees, where huge size differences exist between individuals, indices such as basal area, metric tons per hectare, or canopy cover are more useful than counts. For any measured species that is handled (or sampled noninvasively; Taberlet et al. 1999; Kendall and McKelvey 2008; Schwartz and Monfort 2008), an additional data source is available: the genetic data stored in the organism's tissue. If genetic samples are taken, then these data become another type of spatial data associated with the location where the organism was sampled. As such, genetic data can be analyzed with many of the same approaches used to analyze data of other types that vary spatially.