Latitudinal Correlates of the sizes of mammalian geographical ranges in South America.
JOURNAL OF BIOGEOGRAPHY
Lugar: Oxford; Año: 1994 vol. 21 p. 545 - 559
The geographic distribution of 536 species of South American mammals was used to analyse latitudinal gradients in the north-south and east-west range of species, and to determne how they related to the width of the continent, the size of habitats, regional habitat heterogeneity, seasonality, and species richness. Taxonomic comparisons revealed differences in: (1) the adherence to Rapoport´s Rule (i.e. the progressive increase in the latitudinal extent of species with latitude), (2) the relationship between mean latitudinal range of species and seasonality, (3) the skewness of frequency distribution of geographical range sizes and (4) the relationship between the size of geographical ranges and the number of species found at each latitude. However, all taxa showed that regional habitat heterogeneity is negatively correlated with the longitudinal fraction of the continent occupied by a species. Species with reduced area are clustered around the Andes and coasts, regardless of latitude. Species with the largest ranges are found north of 30S. In spite of this, the shape of the continent does not prevent some taxa to conform to Rapoport´s Rule. This suggests that taxon-dependent factors (e.g. habitat-use, history legacy) could also account for empirical differences observed in the latitudinal variation of geographical ranges among distinct taxa. Thus, the utility of the Rapoport-rescue-hypothesis for understanding the latitudinal patterns in species diversity might be logically constrained. The present study leads to the prediction that some taxa might be more suitable than others when trying to test the Rapoport-rescue-hypothesis.