Geographical and Macroecological Patterns of Tuco-Tucos

Tuco-tucos (Ctenomys sp.) are the most speciose genus of octodontoid rodent and are widely distributed in the southern half of South America. Despite their diversity, species of tuco-tucos rarely co-occur in syntopy and most adjacent species pairs are thought to be contiguously allopatric. Greater understanding of their geographic patterns of species diversity, range size, and body size distribution may provide insights on Ctenomys biogeography. In this chapter, we explored spatial patterns of species richness, geographic range size, and body size of tuco-tucos. We recovered a center of geographic range overlap in northern Argentina, and verified that tuco-tucos have a small range size when compared to other caviomorph families. However, we investigated range exclusivity – the proportion of a species range that is not shared with its congeners – and found that the exclusivity of Ctenomys ranges is comparable to that in other species-rich genera of caviomorphs. This finding challenges the idea that tuco-tuco species have a higher degree of allopatry than other genera. The body size distribution of tuco-tucos is right-skewed, as in other mammal groups, and negatively correlated with latitude, as previously documented. Relationships between richness, range size, and body size with geographical variables were presented and briefly discussed.