Abstract:
Prairie deer mice (Peromyscus maniculatus bairdii) were obtained from Lethbridge, Alberta, Canada (49 0 35' N) and Emporia, Kansas (380 24' N) in order to examine the effects of latitude on genetic variance. The mice were put into
a photoperiod cycle which consisted first of l2L/12D, then constant light (LL), followed by a return to l2L/12D, and
finally, constant darkness (DD). The free-running locomotor activity of the two groups of mice was then compared. A significant difference was found between the circadian activity patterns of the northern and southern mice during exposure to both LL and DD. Genetic variance also was investigated by employing enzyme studies. This was done by gel electrophoresis of the isoenzymes of esterase, lactic dehydrogenase, and xanthine dehydrogenase. Both esterase and xanthine dehydrogenase showed positive evidence of genetic variation in band appearance and migration. In conclusion, this research showed that the genetic components of these two populations of the prairie deer mice vary latitudinally. This was evidenced by statistically significant differences in the endogenous locomotor circadian rhythms, as well as distinctly different enzyme banding patterns.
