Adaptation to Temperate Environments

适应温带环境

• 批准号: 9806278
• 负责人: William Bradshaw
• 金额: $ 40万
• 依托单位: University of Oregon Eugene
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-03-15 至 2004-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9806278&HistoricalAwards=false
• 关键词: Adaptation; Temperate; Environments

Bradshaw9806278The investigators are concerned with factors that affect the ability of plant or animal species to invade and persist in the temperate zone of North America. Range expansion into progressively more northern latitudes should involve two separate adaptations to temperature (a) to the duration and intensity of winter cold and (b) to the timing of seasonal events, i.e., the "fitting" of growth, development, and reproduction into the available growing season. In this proposal, the investigators test explicitly for the relative importance of these two sources of adaptation to temperature over the climatic gradient of eastern and central North America. In a wide variety of studies on how temperature relates to the ecology of organisms, it is usually assumed that environmental temperatures limit range expansion directly, and that range expansion occurs because of adaptive modification of cold tolerance. The investigators argue that the opposite process usually occurs: adaptive modification in cold tolerance takes place after populations are well-established and after the seasonal development and hibernation of populations has adapted to the local seasonal cycle. The investigators will pursue this proposition experimentally, using the pitcher-plant mosquito as our model organism; they will test the specific hypothesis that fitness of this species from the Gulf of Mexico to Canada is due to adaptations that affect the timing of seasonal development and hibernation and not due to adaptations that affect cold-tolerance. These experiments have important implications for global warming. Discussions ofglobal warming are limited to the direct effects of the duration and intensity of temperatures on plant and animal survival. However, adaptation to changes in seasonality can evolve very rapidly in some organisms. When facing global climate change, organisms may not need to confront the extreme temperatures directly; rather they may simply evade these extremes by modifying the timing of important events in the seasonal life history. The investigators seek to determine whether it is the direct effect of change in habitat temperature that is most likely to impact animal fitness, or whether it is the indirect effect of season length that affects fitness and, ultimately, survival.

Bradshaw9806278研究人员关注的是影响植物或动物物种入侵并在北美温带生存的能力的因素。逐步扩大到更北纬的活动范围应包括两个单独的适应温度：(A)适应冬季寒冷的持续时间和强度；(B)适应季节性事件的时间，即生长、发育和繁殖“适应”可用生长季。在这项建议中，研究人员明确测试了这两个适应北美东部和中部气候梯度的温度来源的相对重要性。在关于温度如何与生物体生态相关的各种研究中，通常假设环境温度直接限制了范围的扩展，而范围扩展的发生是由于对耐寒性的适应性修改。研究人员认为，通常会发生相反的过程：在种群建立良好之后，在种群的季节性发育和冬眠适应当地的季节性周期之后，才会发生耐冷性的适应性变化。研究人员将使用猪笼式植物蚊子作为我们的模式生物，通过实验来探索这一命题；他们将测试特定的假设，即这种物种从墨西哥湾到加拿大的适应性是由于影响季节性发育和冬眠时间的适应，而不是由于影响耐寒性的适应。这些实验对全球变暖有重要影响。关于全球变暖的讨论仅限于温度持续时间和强度对动植物生存的直接影响。然而，在某些生物体中，对季节性变化的适应可以进化得非常快。当面对全球气候变化时，生物可能不需要直接面对极端温度；相反，它们可以通过改变季节性生活史上重要事件的发生时间来简单地避开这些极端温度。研究人员试图确定，最有可能影响动物健康的是栖息地温度变化的直接影响，还是影响健康并最终影响生存的季节长度的间接影响。