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Media type:
E-Article
Title:
Intraspecific Differences in the Use of Photoperiod and Temperature as Environmental Cues in White-Footed Mice Peromyscus leucopus
Contributor:
Heath, Harley W.;
Lynch, G. Robert
Published:
University of Chicago Press, 1983
Published in:
Physiological Zoology, 56 (1983) 4, Seite 506-512
Language:
English
ISSN:
0031-935X
Origination:
Footnote:
Description:
This study compared the effects of photoperiod and temperature on populations of Peromyscus leucopus from two different latitudes. Laboratory-reared mice which were descendants of Connecticut (CT) or Georgia (GA) wild-caught animals were exposed to either a long (16L:8D) or short (9L:15D) photoperiod for 12 wk. All mice were kept at 23 C for the first 6 wk, then half of each group was exposed to 13 C for the remaining 6 wk. Nesting was assessed during week 10 and spontaneous torpor during weeks 11-12. At the end of week 12, all mice were killed and examined for the presence of winter pelage. Testicular index, testes weight, seminal vesicle weight, spermatogenic index in males, and reproductive tract weight and follicular index in females were determined. Short days caused gonadal involution, molts to winter pelage, and torpor at both temperatures in CT mice. In contrast, the majority of GA mice remained reproductively competent, and thermoregulatory adjustments were less pronounced. At 23 C, short-day exposed GA mice did not become torpid, and only one animal (6%) molted. AT 13 C 27% of the GA short-day animals entered torpor and 20% molted. Nesting was increased by both short days and cold in CT mice, but only by cold in GA mice. These results indicate that in P. leucopus there is considerable intraspecific variation in the use of photoperiod and temperature as environmental cues.