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: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=389392
• 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.

我们研究了艾伯塔省西南部短暂夏季环境中的鹿鼠和田鼠的生活史，这些环境中的成熟年龄通常延迟至一岁，雏鸟的存活率变化很大，而成虫的存活率很高。这些人口很容易受到干扰，因为流动率和从下降中恢复的速度很慢。最近的食品补充剂研究表明，营养限制会影响雏鸟的生长和成熟以及季节性繁殖，但对雏鸟或成虫的生存没有影响。我们最近对单个围栏和野外小鼠的研究表明，它们在能量和活动方面有相似之处，但单个围栏中的巢穴死亡率远低于野外，这表明捕食或杀婴可能对巢穴死亡率最重要。我们将启动新的研究来调查巢穴捕食（黄鼠狼）和杀婴行为，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供应而异。我们将使用碳和氮的稳定同位素来确定它们是否可以提供有关人群自然饮食变化的有用信息。  潜力是存在的，因为鹿鼠是杂食性的，并且 15N/14N 比率随营养水平的不同而变化（参见 Kelly, 2000.Can. J. Zool.78: 1-27 的综述）。我们首次使用稳定同位素产生的问题多于答案（参见 R1、R3），因为它们可能受到同位素吸收差异、压力以及超过营养性摄食水平的新陈代谢率的影响。在我们解释现场样本的数据之前，需要在受控条件下进行地面实况分析，因此我们将确定同位素的周转率，检查同位素的吸收差异，检查稳定同位素与代谢率和应激水平的关系，检查等热量但可变蛋白质饮食中的氮同位素分馏，并检查饮食、母亲和受抚养后代之间的同位素分馏，所有 在实验室检查现场样本的季节、栖息地和种群差异之前。