Biodiversity patterns, processes and assembly rules of small mammal assemblages in Monte desert, Argentina.

RODRIGUEZ, DANIELA; OJEDA RICARDO ALBERTO

Mendoza, Argentina

Congreso; Xth International Mammalogical Congress; 2009

Internationational Federation of Mammalogists

Different biodiversity patterns can arise at different spatial scales. According to the heterogeneity hypothesis these patterns could be driven by structural habitat features, mostly at regional scale. Nevertheless, inter-specific interaction could also regulate community structure at local scale. These assemblage patterns could be potentiated in arid ecosystems with marked spatial heterogeneity and scarce resources. Particular questions are addressed across spatial scales: How is small mammal diversity additively partitioned into alpha, beta and gamma diversity? How do these patterns vary according to habitat heterogeneity and complexity? What functional traits are driving convergence and divergence in small mammal communities? and, What assembly rules drive our system? We sampled 52 small mammal assemblages along the latitudinal extent of the central Monte Desert. Spatial scales considered were: habitat patch, locality and biome. Total sampling effort was 23,000 night/traps with a total of 411 captures of 12 species. By comparing beta and alpha diversity we found that alpha diversity was bigger than beta at most spatial scales (these varying depending on the index used). At patch scale we found no association of diversity with either heterogeneity or habitat complexity. Nevertheless, at regional scale we found a strong association between these variables (i.e. diversity vs. complexity R2=0.608, p<0.05). According to functional traits, different divergent and convergent traits were mainly explained at all spatial scales [i.e. torpor and body/tail ratio are divergent traits (R2=0.90; p<0.034), and body/tail ratio is also a convergent trait (R2=0.913; p<0.012) at regional scale for the heterogeneity gradient]. We also found complementarity (R2=0.58; p<0.0001) between small mammal species in assemblages of the Monte Desert at local scale, supporting Fox’s assembly rule. Ours results suggest that the structure of small mammal’s assemblages of Monte desert is driven by a combination of several factors at different spatial scales.