The Genetic Basis of Adaptive Differentiation in Two Species of Mimulus

[00:75660 . bradshaw]内华达山脉从海平面上升到1万英尺，植物适应海拔上升的遗传机制将通过实验室和实地实验相结合的方式进行研究。Mimulus cardinalis是一种适应低海拔长而炎热的夏季的植物，它与Mimulus lewisii杂交，后者是一种适应高海拔高山草甸短而凉爽生长季节的近亲。50多年的研究表明，这两个物种杂交的后代在低、中、高海拔地区生存和生长的能力不同。本研究将利用Mimulus染色体的dna遗传图谱，在加利福尼亚中部三个历史上重要的野外站点（Stanford、Mather和Timberline）确定控制生存、生长和繁殖的基因数量。许多亲缘关系密切的物种的基因库由于适应不同环境而产生的地理隔离而保持分离。适应被认为是创造和维持生物多样性的主要手段。适应性进化的速度取决于控制适应性特征的基因数量，如对极端温度的耐受性或生长季节开花的数量。利用分子生物学和基因组图谱的现代方法，首次有可能估计生物体适应不同自然环境所需的基因数量。

0075660BradshawThe genetic mechanism of plant adaptation to increasing elevation, from sea level to 10,000 feet in the Sierra Nevada mountains, will be studied using a combination of laboratory and field experiments. Mimulus cardinalis, a plant species adapted to long, hot summers at low elevation, has been crossed with Mimulus lewisii, a closely-related species adapted to the short, cool growing season found in high-elevation alpine meadows. More than 50 years of research has shown that the offspring of crosses between these two species differ in their ability to survive and grow at low, middle, and high elevations. This study will use DNA-based genetic maps of the Mimulus chromosomes to identify the number of genes controlling survival, growth, and reproduction at three historically important field stations (Stanford, Mather, and Timberline) in central California.The gene pools of many closely related species are kept separate by the geographic isolation resulting from adaptation to different environments. Adaptation is believed to be the principal means by which biological diversity is created and maintained. The pace of adaptive evolution depends upon the number of genes that govern adaptive traits such as tolerance of extreme temperatures or number of flowers produced during the growing season. With modern methods of molecular biology and genome mapping, it is possible for the first time to estimate the number of genes required for organisms to adapt to different natural environments.