Open AccessProblems with areal definitions of endemism: the effects of spatial scaling
Author(s) -
Townsend Peterson A.,
Watson David M.
Publication year - 1998
Publication title -
diversity and distributions
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.918
H-Index - 118
eISSN - 1472-4642
pISSN - 1366-9516
DOI - 10.1046/j.1472-4642.1998.00021.x
Subject(s) - endemism , geography , scaling , ecology , species richness , multidimensional scaling , scale (ratio) , macroecology , range (aeronautics) , biodiversity , global biodiversity , cartography , biology , statistics , mathematics , materials science , geometry , composite material
Summary The concept of endemism is useful in quantifying the biological uniqueness of an area, and has been used by many authors as a meaningful alternative to simple species richness. The traditional definition of endemism includes those species with ranges restricted to a particular region, and therefore is useful only in reference to that region. To compare different regions, however, a standardized approach is required, so several authors began using area‐based definitions. Accordingly, those species with ranges smaller than a particular area (e.g. 50,000 km 2 ) are deemed endemic. Nevertheless, several problems are associated with this approach: as the area threshold changes, scaling of endemism also changes, producing a different picture of endemism for each spatial scale. Moreover, the areal definition assumes equal levels of heterogeneity in different landscapes (clearly a simplification), which overemphasizes fine‐grained regions. Herein, the importance of distinguishing the regional definition (endemism) from the areal definition (range restriction) is emphasized, and investigators are encouraged to consider multiple spatial scales and geographic dimensions in evaluations of biodiversity.