Demographic performance of a large herbivore: effects of winter nutrition and weather
Demographic performance of a large herbivore: effects of winter nutrition and weather
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DOI：
10.1002/ecs2.3328
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发表时间：
2021-01-01
期刊：
影响因子：
2.7
通讯作者：
Rowland, Mary M.
中科院分区：
文献类型：
--
作者：
Jackson, Nathan J.;Stewart, Kelley M.;Rowland, Mary M.
一个种群的人口比率的变化反映了个体将可用能量分配给相互竞争的生活史策略。物种表现出慢节奏的生活史往往优先考虑能源分配到成年人的生存比任何单一的生殖事件，因此最大限度地提高未来的生殖潜力。成年雌性有蹄类动物的存活率通常很高，变异性很小，而幼崽的存活率较低，而且往往变异很大。当成虫存活率高，变异性低时，幼虫存活率可能对种群的增长或下降产生更大的影响。天气也可能通过影响幼鸟或成年鸟的存活直接影响种群动态，或通过影响种群增长率的成年雌鸟营养状况的变化间接影响种群动态。我们实验操纵饲料供应在冬季，补充本地饲料与高能量颗粒饲料随意，一个子集的一个人口的黑尾鹿（Odocoileus hemionus），以了解冬季营养对成年女性的生存和他们的年轻出生的第二个夏天。我们评估了冬季营养，基于个体的参数和环境协变量对2013年至2018年成年雌性黑尾鹿和2014年至2016年新生黑尾鹿生存的影响。我们记录了2017年成年雌性黑尾鹿的年存活率下降了26%，以应对前一个冬天积雪增加的情况。新生儿出生的女性在冬季分娩前接受增强营养有较高的生存率断奶（0.49，SE = 0.12），新生儿出生的女性没有接受增强营养（0.29，SE = 0.07）。我们没有观察到增强冬季营养对成年女性的生存的影响。我们的研究结果表明，冬季营养的孕产妇女性可能会影响少年的生存，并证明饲料质量的重要性，成年女性在怀孕中期。虽然我们无法检测到的影响，冬季饲料的成年人的生存，深冬雪的直接影响，导致成年女性的生存率较低。在我们的研究人群中，成年女性的低生存率表明人口正在下降。
Variation among demographic rates for a population reflects the allocation of available energy by individuals to competing life-history strategies. Species exhibiting slow-paced life histories often prioritize energy allocation to adult survival over any single reproductive event, therefore maximizing future reproductive potential. Survival of adult female ungulates is generally high with little variability, whereas survival of young is lower and often highly variable. When adult survival is high with low variability, juvenile survival may have a proportionally greater effect on population growth or decline. Weather also may affect population dynamics directly by influencing survival of young or adults, or indirectly through changes in nutritional condition of adult females that influence population growth rates. We experimentally manipulated forage availability during winter, by supplementing native forage with high-energy pelleted feed ad libitum, to a subset of a population of mule deer (Odocoileus hemionus) to understand the effects of winter nutrition on survival of adult females and their young born the subsequent summer. We evaluated the effects of winter nutrition, individual-based parameters, and environmental covariates on survival of adult female mule deer from 2013 to 2018, and neonatal mule deer from 2014 to 2016. We documented a 26% decrease in annual survival of adult female mule deer in 2017 in response to increased snowpack during the preceding winter. Neonates born to females that receive enhanced nutrition during winter preceding parturition had higher survival to weaning (0.49, SE = 0.12), compared to neonates born to females that did not receive enhanced nutrition (0.29, SE = 0.07). We observed no effect of enhanced winter nutrition on survival of adult females. Our results suggested winter nutrition of maternal females may influence juvenile survival and demonstrates the importance of forage quality available to adult females during mid-pregnancy. Although we were unable to detect an effect of winter forage on survival of adults, direct effects of deep winter snow resulted in lower survival of adult females. Low survival of adult females in our study population is indicative of a declining population.