Ecological strategies of small mammals in seasonal environments

季节性环境下小型哺乳动物的生态策略

• 批准号: 6688-2006
• 负责人: Millar, John
• 金额: $ 4万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2007
• 资助国家: 加拿大
• 起止时间: 2007-01-01 至 2008-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=366509
• 关键词: Ecological; strategies; small; mammals; seasonal

We study the life histories of deer mice and voles in short-summer environments in southwestern Alberta where age at maturation is often delayed to one year of age, survival of nestlings is variable, and survival of adults is  high. These populations are vulnerable to disturbance because turn-over rates and recovery from declines are slow. Recent food supplementation studies showed  nutritional constraints on nestling growth and maturation as well as seasonal breeding, but had no effect on nestling or adult survival. Our recent studies of mice in individual enclosures and in the wild showed similarities in energetics and activity, but nest mortality in individual enclosures was much lower than in the wild, suggesting that predation or infanticide may be most important to nest mortality. We will initiate  new studies to investigate nest predation (weasels) and infanticide, as well as the effects of parasites on growth and maturation. Finally, responses to extra food vary with the availability of natural foods. We will use stable isotopes of carbon and nitrogen to determine if they can provide useful information about changes in natural diets within populations.  The potential is  there because  deer mice are omnivorous and 15N/14N ratios vary among trophic levels (See Kelly, 2000.Can. J. Zool.78: 1-27 for a review). Our first  use of stable isotopes  yielded more questions than answers (See R1, R3) because they may be influenced by differential absorption of isotopes, stress, and rates of metabolism over and above trophic feeding levels. Ground-truthing  under controlled conditions is needed before we can  interpret  data from field samples, so we will determine the turn-over rates of isotopes, examine the differential absorption of isotopes,  examine stable isotopes in relation to rates of metabolism and  levels of stress,  examine nitrogen isotope fractionation among isocaloric but variable protein diets, and  examine isotope fractionation between diet, mothers, and dependent offspring, all in the laboratory,  before examining  field samples for seasonal, habitat, and population differences.

我们研究了阿尔伯塔西南部短夏环境中鹿鼠和田鼠的生活史，在那里成熟的年龄通常延迟到一岁，雏鸟的存活率是可变的，成年鼠的存活率很高。这些种群很容易受到干扰，因为更替率和从衰退中恢复的速度很慢。最近的食物补充研究表明，营养限制了雏鸟的生长和成熟以及季节性繁殖，但对雏鸟或成虫的存活率没有影响。我们最近对单独圈养的小鼠和野外的小鼠进行的研究表明，在能量和活动方面存在相似性，但单独圈养的小鼠巢死亡率远低于野外，这表明捕食或杀婴可能是导致巢死亡率的最重要因素。我们将开展新的研究，以调查巢捕食（黄鼠狼）和杀婴，以及寄生虫对生长和成熟的影响。最后，对额外食物的反应因天然食物的可得性而异。我们将使用碳和氮的稳定同位素来确定它们是否能提供有关人群自然饮食变化的有用信息。潜在的原因是鹿鼠是杂食性的，15N/14N比率在不同的营养水平上是不同的（见Kelly， 2000）。[j] .中国生物医学工程学报，2004,(2):1- 7。我们对稳定同位素的首次使用产生了更多的问题而不是答案（见R1， R3），因为它们可能受到同位素的不同吸收、压力和营养喂养水平以上的代谢率的影响。在我们能够解释来自野外样本的数据之前，需要在受控条件下进行地面真相调查，因此我们将确定同位素的周转率，检查同位素的差异吸收，检查与代谢率和应激水平相关的稳定同位素，检查等热量但变化的蛋白质饮食中的氮同位素分异，以及检查饮食、母亲和依赖后代之间的同位素分异。在检查野外样本的季节、栖息地和种群差异之前，所有这些都在实验室进行。