Department of Ecosystem Science and Management, Pennsylvania State University, 117 Forest Resources Building, University Park, PA 16802, USA.
Philos Trans R Soc Lond B Biol Sci. 2013 Jul 8;368(1624):20120480. doi: 10.1098/rstb.2012.0480. Print 2013 Aug 19.
Many studies have addressed the effects of climate change on species as a whole; however, few have examined the possibility of sex-specific differences. To understand better the impact that changing patterns of snow-cover have on an important resident Arctic mammal, we investigated the long-term (13 years) phenology of hibernating male arctic ground squirrels living at two nearby sites in northern Alaska that experience significantly different snow-cover regimes. Previously, we demonstrated that snow-cover influences the timing of phenological events in females. Our results here suggest that the end of heterothermy in males is influenced by soil temperature and an endogenous circannual clock, but timing of male emergence from hibernation is influenced by the timing of female emergence. Males at both sites, Atigun and Toolik, end heterothermy on the same date in spring, but remain in their burrows while undergoing reproductive maturation. However, at Atigun, where snowmelt and female emergence occur relatively early, males emerge 8 days earlier than those at Toolik, maintaining a 12-day period between male and female emergence found at each site, but reducing the pre-emergence euthermic period that is critical for reproductive maturation. This sensitivity in timing of male emergence to female emergence will need to be matched by phase shifts in the circannual clock and responsiveness to environmental factors that time the end of heterothermy, if synchrony in reproductive readiness between the sexes is to be preserved in a rapidly changing climate.
许多研究都探讨了气候变化对整个物种的影响；然而，很少有研究考察性别的具体差异的可能性。为了更好地了解冰雪覆盖模式变化对北极地区一种重要的本地哺乳动物的影响，我们调查了生活在阿拉斯加北部两个附近地点的冬眠雄性北极地松鼠的长期（13 年）物候学，这两个地点的冰雪覆盖情况存在显著差异。此前，我们证明了冰雪覆盖会影响雌性的物候事件的时间。我们在这里的研究结果表明，雄性异温性的结束受土壤温度和内在的年节律钟的影响，但雄性从冬眠中苏醒的时间受雌性苏醒时间的影响。两个地点（Atigun 和 Toolik）的雄性在春季的同一天结束异温性，但在进行生殖成熟的过程中仍留在洞穴中。然而，在冰雪融化和雌性出现相对较早的 Atigun，雄性比 Toolik 提前 8 天出现，维持了在每个地点都存在的雌雄出现之间的 12 天间隔，但减少了对生殖成熟至关重要的预苏醒恒温期。如果要在快速变化的气候中保持两性之间的生殖准备同步，那么雄性出现对雌性出现的这种时间敏感性将需要与年节律钟的相位变化以及对环境因素的响应相匹配，这些因素会影响异温性的结束。
