| Abstract: | Weanling male and female field voles from laboratory stock and from the F1 generation of wild-caught animals were placed in a long (16L:8D) or short (6L:18D) photoperiod for 28 or 56 days. Both types of field vole showed the well-established effect of photoperiod upon sexual maturation, with animals in the long photoperiod having larger and more active gonads than animals in the short photoperiod. After 28 and 56 days laboratory stock females were more mature, sexually, and had a higher growth rate than did Wild F1 females. There was no difference between the two types of males at 28 days, but by 56 days laboratory stock males were more sexually mature and had a higher growth rate than did Wild F1 males. These differences between the two types occurred in the long and short photoperiods. There was no interaction between photoperiod and type of vole. The use of laboratory stock animals in experiments could lead to an incorrect assessment of the effect of photoperiod in the control of seasonal breeding in wild populations. |
