Studying the mating systems is one of the most significant areas in behavioral ecology. Previously studies showed that the mating system inTupaia belangeriwere monogamy and polygamy. In order to investigate the mating system ofT. belangeriin the field environment, testis mass and body mass in maleT. belangeriduring the breeding season were measured, combined with 60 primate species of monogamy, polygamy and polyandry based on the comparison analysis of testis mass and body mass. The results showed that testis mass increased with the increasing of body mass in all species (r=0.31,P<0 .05), significant difference in testis mass and body mass among the 3 mating systems (testis mass:F=11.36,P<0 .01; body mass:F=4.09,P<0 .05) were detected. these results showed that a significant difference of testis mass occurs among different mating systems, and the mating system ofT. belangerimay be monogamy. Moreover, the present results suggest that testis size can be used as a reliability factor for predicting the mating system in mammals.
