Spatial and Temporal Heterogeneity of Selection in an Early Successional Field: Patterns and Processes

9307202微观进化理论中经常提到Stratton环境异质性，但对选择变异的空间或时间尺度知之甚少。自然选择的进化结果关键取决于适应度的变化是细粒度的还是过程粒度的。例如，后代在具有相似适应度效应的微站点中的扩散将促进局部适应，而扩散半径内的异质性有利于多面手的进化。选择的变异是由基因类型的相对适合度(基因×环境互作适合度)的反转来定义的。我以前的工作表明，土壤养分和植被模式在米的尺度上不同，并影响Drigelon的绝对适合度，但不同基因型之间的排名适合度的变化发生在厘米尺度上。因此，选择性异质性可能与容易观察到的生态异质性有质的不同。采用%空间自相关分析方法，对两年中12个品种灯盏花的相对适合度的时空变异进行了研究。我将比较选择中纯粹的空间和时间变化的大小，以及不同年份适合度峰值位置的二阶变化。同时测量土壤养分、光、水和背景植被将确定与田间相对适合度相关的因素；然后将使用温室实验来确认这些偶然关系。此外，我将在几个空间尺度上测试选择中的变异是否由频率依赖的、基因型相互作用引起。这项研究将是自然植物种群选择时间变异的第一个研究之一，也是第一个测试选择空间模式随时间变化的稳定性的研究之一。

9307202 Stratton Environmental heterogeneity is often invoked in theories of microevolution but little is known of the spatial or temporal scale of variation in selection. The evolutionary outcome of natural selection depends critically on whether variation in fitness is fine grained or course grained. For example, dispersal of offspring in microsites with similar fitness effects will promote local adaptation, while heterogeneity within the dispersal radius favors the evolution of generalists. Variation in selection is defined by reversals in the relative fitness of genotypes (genotype x environmental interactions for fitness). My previous work has shown that soil nutrients and vegetation patterns vary on scale of meters and affect the absolute fitness of Drigeron, but changes in rank fitness among genotypes occur on a scale of centimeters. Selective heterogeneity may thus qualitatively different from easily observed ecological heterogeneity. %%% Spacial autocorrelation analysis will be used to measure spatial and temporal variation in the relative fitness of 12 genotypes of Erigeron annuus over two years. I will compare the magnitude of pure spatial and temporal variation in selection with second order changes in the location of fitness peake among years. Simultaneous measurements of soil nutrients, light, water, and background vegetation will identify factors correlate with the relative fitness in the field; greenhouse experiments will then be used to confirm the casual relationships. Furthermore, I will test whether variation in selection is caused by frequency dependent, genotype genotype interactions at several spatial scales. This research will be among the first studi es of temporal variation in selection in natural plant populations, and the first to test the stability of spatial patterns of selection through time.