Territory acquisition mediates the influence of predators and climate on juvenile red squirrel survival
Territory acquisition mediates the influence of predators and climate on juvenile red squirrel survival
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领地获取调节捕食者和气候对幼年红松鼠生存的影响
DOI：
10.1101/594036
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. McAdam
中科院分区：
文献类型：
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作者：
Jack G. Hendrix;D. Fisher;A. Martinig;S. Boutin;B. Dantzer;J. Lane;A. McAdam
1) 幼体存活至首次繁殖是一个关键的生活史阶段。当这一时期恰逢冬季气候恶劣或食物短缺等恶劣环境条件时，存活可能极具挑战性，因此同批幼体的存活率可能差异很大。然而，幼体体型小且具有扩散性，这使得研究它们的存活情况很困难。
2) 在具有领地性的物种中，一个关键的生活史事件是领地的获取。领地有望提高存活率，但它如何做到这一点（可能是通过调节死亡率）往往并不明确。我们测试了领地获取的时间如何影响北美红松鼠（以下简称红松鼠）幼体的存活，以及这一事件的时间如何调节死亡原因。我们假设在贮藏季节之前获得领地会降低幼体在冬季对捕食或气候因素的敏感性。
3) 利用27年关于个体标记的红松鼠幼体存活的数据，我们测试了领地获取时间如何影响存活，红松鼠捕食者的种群密度和冬季平均温度是否与个体存活概率相关，以及领地所有权是否调节这些影响。
4) 在捕食者数量多的年份和更寒冷的冬季，幼体存活率较低。秋季拥有领地的个体不易受到加拿大猞猁，可能还有鼬属和貂属动物的捕食。在寒冷的冬季，秋季拥有领地的个体存活率较低，而未拥有领地的个体在寒冷冬季存活率较高。
5) 我们的研究结果表明，像领地获取这样的生活史事件的时间如何能够直接影响存活，并且还能调节生命后期生物和非生物因素的影响。这有助于更好地理解关键生活史事件时间的适合度后果。
1) Juvenile survival to first breeding is a key life history stage. Survival through this period can be particularly challenging when it coincides with harsh environmental conditions like winter climate or food scarcity, and so cohort survival can be highly variable. However, the small size and dispersive nature of juveniles makes studying their survival difficult. 2) In territorial species, a key life history event is the acquisition of a territory. A territory is expected to enhance survival, but how it does so, possibly through mediating mortality, is not often identified. We tested how the timing of territory acquisition influenced the survival of juvenile North American red squirrels Tamiasciurus hudsonicus, hereafter red squirrels, and how the timing of this event mediated sources of mortality. We hypothesized that securing a territory prior to the caching season would reduce juvenile susceptibility to predation or climatic factors over winter. 3) Using 27 years of data on the survival of individually-marked juvenile red squirrels, we tested how the timing of territory acquisition influenced survival, whether the population density of red squirrel predators and mean temperature over winter were related to individual survival probability, and if territory ownership mediated these effects. 4) Juvenile survival was lower in years of high predator abundance and in colder winters. Autumn territory owners were less susceptible to lynx Lynx canadensis, and possibly mustelid Mustela and Martes spp., predation. Autumn territory owners had lower survival in colder winters, while non-owners had higher survival in cold winters. 5) Our results show how the timing of a life history event like territory acquisition can directly affect survival and also mediate the effects of biotic and abiotic factors later in life. This engenders a better understanding of the fitness consequences of the timing of key life history events.