LARGE-SCALE RICHNESS PATTERNS, BIOGEOGRAPHY AND ECOLOGICAL DIVERSIFICATION IN CAVIOMORPH RODENTS

RICARDO A. OJEDA; AGUSTINA NOVILLO; OJEDA, AGUSTINA A

Biology of caviomorph rodents: diversity and evolution

SAREM

Año: 2015; p. 121 - 138

Hystricognath rodents probably arrived from Africa and diversified in major clades during the Eocene- Oligocene. Caviomorph rodents radiated in different directions involving body size, ecomorphological, physiological and behavioral traits which make them convergent to several groups of mammals. The aim of this chapter is to analyze and integrate the biogeographical and ecological diversification within the phylogeny of the caviomorph major clades, followed by a case study of diversification of aridland octodontids. The caviomorph rodents are grouped into four superfamilies (Cavioidea, Chinchilloidea, Erethizontoidea and Octodontoidea), 13 families, 56 genera and 246 species. The major findings of our contribution are: a) the two macrohabitats with highest species density are the Amazonian and the Atlantic forest; b) approximately 35% of caviomorphs show small or restricted geographic ranges; c) species richness is linked to an effect of area and productivity; d) the Amazonia is suggested as the most likely macrohabitat for the evolution of proto-caviomorphs; e) the most likely proto-caviomorph macroniches are associated with saxicolous modes of life and a diet of grasses leaves and fruits; f) the proto- Monte aridland has been suggested as the ancestral habitat of octodontids, followed by their biogeographical and ecological diversification associated with contrasting environmental conditions in both sides of the Andes; g) the colonization of a new adaptive zone and expanded geographic range of Tympanoctomys, has been the result of the evolution of behavioral, ecomorphological, and physiological traits which enabled a better utilization of open xeric habitats, and hypersaline food resources than its close relatives. The caviomorphs represent a good research model to explore and disentangle the biogeographical and ecological diversification of one of the most conspicuous and native lineages of South American mammals. Our global analysis and proposed diversification hypotheses highlight some major findings and pinpoint research lines and gaps that deserve continuing investigations.