Molecular Genetics of Pre-Mating Reproductive Isolation in Mimulus

小行星9616522 在加州的内华达州山脉中部，有两种猴花，Mimulus lewisii和M. cardinalis，它们由不同的动物授粉- M. lewisii为熊蜂授粉，M.红雀由蜂鸟授粉。 每种Mimulus的花在颜色，大小，形状和花蜜生产方面都有所不同，以最好地吸引合适的授粉者。 这两种猴花在自然界中不会杂交，因为它们的授粉者不同，但人工杂交可以通过人工授粉很容易地产生。 杂交后代显示出各种各样的花特征，因为每个后代都从蜜蜂授粉的祖先和蜂鸟授粉的祖先遗传了一部分基因组。 没有两个杂交后代是完全一样的。 200多只杂交后代将被带到加州的约塞米蒂国家公园，那里有M。lewisii和M.红雀是自然地聚集在一起的，大黄蜂和蜂鸟的造访率是通过直接观察来测量的。 新的基因组图谱技术最初是为研究人类疾病和动植物育种而开发的，将用于确定花中哪些基因负责吸引大黄蜂和蜂鸟。 工作假设是，一些基因，如那些控制花的颜色和花蜜生产，将有很大的影响，授粉者选择访问一个特定的花。 研究物种形成的遗传学--一个物种分裂成两个或更多新物种的过程--对于了解生物多样性的起源至关重要。 物种形成是由于遗传变化阻止了两个物种的杂交。 自达尔文以来，人们一直在争论物种形成所需的遗传变化的数量和幅度。 一种观点认为，生殖隔离是许多突变的累积结果，每个突变的影响都很小，在很长一段时间内。 另一些人则认为，一些影响较大的基因发挥了重要作用，物种形成可能会迅速发生。 这个问题一直没有得到解决，主要是因为详细的遗传学研究仅限于少数生物，如果蝇，它们作为实验模型有很长的历史。 基因组研究方法的改进使利用野生猴头花物种建立现代实验室分子生物学与野外生态学研究的综合体成为可能。 这种通用方法可以用来解决生物学中许多长期存在的问题。

9616522 Bradshaw In the central Sierra Nevada mountains of California there are two monkeyflower species, Mimulus lewisii and M. cardinalis, which are pollinated by different animals -- M. lewisii is bumblebee-pollinated, while M. cardinalis is pollinated by hummingbirds. The flowers of each Mimulus species differ in color, size, shape, and nectar production to best attract the appropriate pollinator. The two monkeyflower species do not crossbreed in nature because of their different pollinators, but artificial hybrids can be produced easily by hand-pollination. Offspring from the hybrids display a tremendous variety of floral traits, since each offspring has inherited part of its genome from a bee-pollinated ancestor and part from a hummingbird-pollinated ancestor. No two hybrid offspring are exactly alike. More than 200 hybrid offspring will be taken to Yosemite National Park in California, where M. lewisii and M. cardinalis are found together naturally, and the rates of bumblebee and hummingbird visitation measured by direct observation. New genome mapping techniques, originally developed for studying human disease and for plant and animal breeding, will be used to determine which genes in the flowers are responsible for attracting bumblebees and hummingbirds. The working hypothesis is that a few genes, such as those governing flower color and nectar production, will have a large impact on which pollinator chooses to visit a particular flower. Investigating the genetics of speciation -- the process by which one species splits into two or more new species -- is fundamental to understanding the origin of biodiversity. Speciation results from genetic changes that prevent the two species from crossbreeding. Since Darwin, there has been debate about the number and magnitude of genetic changes required for speciation. One view is that reproductive isolation is the cumulative result of many mutations, each with a small effect, over long periods of time. Alternatively, others have suggested that a few genes of large effect play a prominent role, and that speciation could occur rapidly. This issue has not been resolved, largely because detailed genetic studies have been limited to a few organisms, such as fruit flies, which have a long history as experimental models. Improved methods in genome research make it feasible to use wild monkeyflower species to establish a synthesis of modern laboratory molecular biology with ecological studies in the field. This general approach could be used to address many long-standing questions in biology.