PRF/J: Quantitative Genetics of Adaptation and Apparent "Constraint" in a Desert Annual

PRF/J：沙漠一年生适应和明显“约束”的定量遗传学

• 批准号: 9002330
• 负责人: Gordon Fox
• 金额: $ 5.88万
• 依托单位: Fellowships
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-09-01 至 1992-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9002330&HistoricalAwards=false
• 关键词: PRF; Quantitative; Genetics; Adaptation; Apparent

This research examines the genetic architecture of several demographic traits and underlying physiological mechanisms in the model systems Eriogonum abertiamum, a desert annual. The work is designed to further understanding of the genetic basis for life history adaptation and of apparent evolutionary "constraints." More Sonoran than Chihuahuan Desert Eriogonums begin flowering in spring, but populations in both regions retain the ancestral character of biseasonal reproduction (spring and summer). Demographic and genetic studies suggest that natural selection may explain earlier Sonoran flowering. However, retention of Biseasonality is not consistent with adaptive explanations in Sonoran populations: Expected summer fecundity does not outweigh the risk of between-season mortality. Fossil, distributional, and biogeographic evidence suggest the same conclusion. Correlations among life history traits may block selection for increased spring fecundity, as suggested by preliminary field and greenhouse studies. Selection experiments are proposed to determine a) whether heritabilities and genetic correlations among demographic traits are significantly different from zero; and b) whether selection on the correlations themselves can change their signs, i.e., whether the correlations can act as constraints. Sib analyses of growth and allocation traits--which underlie demographic traits--will examine genetic variation for these traits both within and between populations.

本研究考察了沙漠一年生植物Eriogonum abertiamum模型系统中几种人口统计学特征的遗传结构和潜在的生理机制。这项工作旨在进一步了解生命史适应的遗传基础和明显的进化“限制”。索诺拉沙漠雄蕊草在春季开始开花的数量多于奇瓦瓦沙漠雄蕊草，但这两个地区的雄蕊草种群都保留了祖先的四季繁殖特征（春季和夏季）。人口统计学和遗传学研究表明，自然选择可以解释索诺拉树开花时间较早的原因。然而，双季节性的保留与索诺兰种群的适应性解释并不一致：预期的夏季繁殖力并不超过季节之间死亡的风险。化石、分布和生物地理证据都表明了同样的结论。初步的田间和温室研究表明，生活史性状之间的相关性可能会阻碍春季繁殖力增加的选择。提出了选择实验，以确定a)人口统计学性状之间的遗传力和遗传相关性是否显著不同于零；b)对相关性本身的选择是否可以改变其符号，即相关性是否可以作为约束。Sib对构成人口特征基础的生长和分配特征的分析，将检验这些特征在种群内部和种群之间的遗传变异。