Department of Biological Sciences, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada.
Assiniboine Park Zoo, 2595 Roblin Boulevard, Winnipeg, MB, R3R 0B8, Canada.
Sci Rep. 2021 Nov 4;11(1):21684. doi: 10.1038/s41598-021-01214-5.
Hibernating ground squirrels rely on a short active period for breeding and mass accrual, and are thus vulnerable to extreme climate events that affect key periods in their annual cycle. Here, we document how a heatwave in March 2012 led to a phenological mismatch between sexes in Richardson's ground squirrels (Urocitellus richardsonii). Females emerged from hibernation and commenced breeding earlier in 2012 relative to average female emergence. Although males had descended testes and pigmented scrota, it appeared that not all males were physiologically prepared to breed since 58.6% of males had non-motile sperm when breeding commenced. Body condition, relative testes size, and the relative size of accessory glands were significant predictors of sperm motility. Males with non-motile sperm had smaller accessory glands than males with motile sperm. There was no decrease in the number of juveniles that emerged in 2012 or female yearlings recruited in 2013, nor did juveniles emerge later than other years. The impact of this heatwave on male ground squirrels emphasizes the importance of assessing the consequences of climate change on the breeding success of hibernating species in both sexes, since the different sensitivity to external cues for emergence led to a mismatch in timing under this event.
冬眠地松鼠依靠短暂的活跃期进行繁殖和大量积累，因此容易受到影响其年周期关键时期的极端气候事件的影响。在这里，我们记录了 2012 年 3 月的热浪如何导致草原榛睡鼠（Urocitellus richardsonii）的性别出现物候期不匹配。与平均雌性出现时间相比，雌性在 2012 年更早地从冬眠中苏醒并开始繁殖。尽管雄性的睾丸已经下降并出现色素沉着的阴囊，但似乎并非所有雄性都在生理上准备好繁殖，因为当繁殖开始时，有 58.6%的雄性精子没有活力。身体状况、相对睾丸大小和附属腺的相对大小是精子活力的重要预测因子。没有活力的精子的雄性附属腺比有活力的精子的雄性附属腺小。2012 年出生的幼仔数量或 2013 年招募的雌性幼仔数量没有减少，幼仔的出现也没有晚于其他年份。这场热浪对雄性地松鼠的影响强调了评估气候变化对冬眠物种繁殖成功率的影响的重要性，因为在这种情况下，对外部线索的不同敏感性导致了时间上的不匹配。
