Reproductive strategies in Akodon azarae (Rodentia, Muridae)

• SUÁREZ, O.V., BUSCH M. AND KRAVETZ, F. O.

Canadian Journal of Zoology

National Research Council Canada

Lugar: Ottawa, Canada; Año: 2004 vol. 82 p. 1572 - 1577

The balance between litter size and the quality of offspring is a central feature to many optimal litter size theories. We analized the reproductive strategies of Akodon azarae  females, according to maternal life histories and the time of birth. Litter size decresed significantly from spring to autumn. A significant birth season effect on mass at birth was observed. A compensatory effect of growth rate was evident during lactation. During spring and early summer overwintered females produced an average of 5 young, with maximun survival at weaning. Females born during the current reproductive season showed  a smaller litter size, probably because they favor residual reproductive value with respect to current reproduction since they have a higher life expectancy and future chances of mating than over wintered females. Mortality reached 50% at weaning for summer litter from young mothers eheresa it declined to 22.2 % in autumn. Differences in both parental investment and offspring survival suggest that the litter size in A. azarae varies alon the reproductive period and is dependent both on females life history and on environmental conditions.