The geographical distribution of biodiversity, threats of biodiversity and ecosystem loss, and regions where conservation efforts should focus are not evenly distributed, but display distinct spatial patterning at all scales, from local to global (Brooks et al., 2006; Kremen et al., 2008). Species richness decreases from the equator poleward (Figure 2.2). Within this general pattern, certain geographical areas have notably high numbers of species, many found nowhere else in the world. These areas of high endemic species richness are referred to as biodiversity hotspots and are often regions prone to significant ongoing ecosystem alteration and loss (Figure 2.2). The role that location and geographical context play on biodiversity and ecosystem loss makes the geographical sciences integral to understanding this issue.
Through field studies, remote sensing, and ecological modeling, the geographical sciences document and explain biodiversity distribution and contribute to its preservation through strategies aimed at optimizing conservation (Church et al., 2003). Scientists are still seeking to determine how many species of plants and animals the planet supports. The lack of information is particularly notable in marine and freshwater systems, which have received less attention than their terrestrial counterparts (Richardson and Poloczanska, 2008).