INTENSITY OF MALE REPRODUCTION IN BRANDT VOLE MICROTUS-BRANDTI

A new method based on polygonal regression analysis to investigate the relationship between the testis (or seminal vesicle) length and body mass were used to study the dynamics of male reproductive intensity of Brandt's voles Microtus brandti (Radde, 1861). The results showed tha t the turning (join) points which could be regarded as the minimum bod y masses commencing sexual development increased from spring to autumn . The slope rates of regression equations which represent the sexual g rowth rate decreased from spring to autumn. This indicated that the se xual development of males had obvious seasonality similiar to that of the females. By comparing two years, we could find that the slopes in 1987 (population increasing year) were significantly higher than those of 1988 (population decreasing year). The slopes and the percentage o f the voles with body mass larger than the turning point might be reli able indexes of male reproductive intensity for studies of population dynamics in rodents.