SEX-BIASED DISPERSAL OF CALOMYS MUSCULINUS (RODENTIA: SIGMODONTINAE) IN LINEAR HABITATS

LUCÍA SOMMARO; MARINA CHIAPPERO; ANDREA STEINMANN; JOSÉ PRIOTTO

Mendoza, Argentina

Congreso; 10th International Mammalogical Congress; 2009

ABSTRACT. We performed multilocus spatial genetic autocorrelation (SGA) analyses at a fine geographic scale in central Argentina in order to study sex-biased dispersal in Calomys musculinus. We conducted the analyses in autumn (at the end of breeding period, highest population density) and winter (nonbreeding period; low density). Two transects with five and two with three lines of 30 traps, separated for 500m, were set along the weedy borders of secondary roads in an agroecosystem near the city of Río Cuarto (central Argentina). All traps were georeferenced using a GPS. We analyzed eight specific microsatellite loci in 77 individuals captured in autumn and 54 individuals in winter. We used the program GenALEx 6.2 to estimate spatial genetic structure. In autumn, when population density peaked, and reproductive activity was still high, males showed the highest dispersal rate (autocorrelation was not significant). Females showed SGA at short distances (autocorrelation was positive and significant up to 66m). In winter, males showed a significant structuring up to 276m. Females did not show significant SGA. Male movements are strongly influenced by search for mates, whereas in females vegetation cover, quality, abundance and distribution of food are most important. In autumn, the habitat patch conditions are still suitable, there are a high number of reproductive active females, therefore a male-biased dispersal is observed. In winter, habitat conditions are poor and suitable habitat patches are sparse, this resulted in a high dispersal of females. Thus the sex-biased dispersal in C. musculinus vary in relation to reproductive activity and habitat patch conditions.