Genetic differentiation among geographically and ecologically divergent populations of the small cavy, Microcavia australis.

PAOLA L. SASSI; MARINA B. CHIAPPERO; CARLOS BORGHI; CRISTINA N. GARDENAL

Mendoza

Congreso; 10th International Mammalogical Congress; 2009

The small cavy Microcavia australis, a colonial and fossorial cavid rodent, occurs over a large distribution range in South American arid zones, which are typically heterogeneous and unpredictable environments. The species was found to be versatile in coping with seasonal and spatial variability through changes in morphology (digestive organs size), physiology (energy extraction efficiency) and behaviour (dietary selection). Habitat and ecological variables have explained differences in social behavior and life history traits of this species as well. In order to complement previous ecological physiology studies, the objective of the present work was to analyse levels of genetic variability and differentiation among four populations of the small cavy that differ in habitat type, altitude, vegetation and precipitation. We used two kinds of molecular markers, giving information about different parts of the genome: we amplified and sequenced the mitochondrial control region (Dloop) and used the Inter Simple Sequence Repeats (ISSR) technique to obtain information about the variability in the non-coding portion of the nuclear genome. All markers were analysed using the program Arlequin. ISSR variability levels were high in all populations (band diversity index M from 0.305 to 0.345). Nucleotide diversity in populations from high altitudes was one order of magnitude smaller than in lowlands populations (p 0.001 versus 0.01/0.028); haplotype diversity was also smaller in highland populations (h 0.700 versus 0.844/0.944). Both kinds of markers revealed similar levels and patterns of genetic differentiation. Pairwise levels of differentiation varied greatly (FST from 0.039 to 0.439 for ISSR and from 9.000×10-5 to 0.933 for mtDloop), all comparisons being statistically significant except for the two highland populations. Only one out of 17 haplotypes found was shared among populations; remaining haplotypes were exclusive. Our results show that there is also a genetic differentiation that correlates with differences found at the morphological, physiological and behavioural differences found among M. australis populations.