REU: Genetic Variability in Bryophyte Populations

性别的进化意义是进化生态学的中心问题。预测有性生殖和无性生殖的相对益处的模型不断涌现，但很少有实证检验。这项研究的目的就是提供一个这样的测试，使用森林苔藓植物，透明四射苔藓。苔藓植物具有高度的生境特异性和广泛的繁殖方式，是检验不同环境中有性或无性生殖有效性假说的理想系统。已经证明，一些无性物种的遗传变异性水平与有性物种的遗传变异性水平相当。无性繁殖不一定会降低遗传变异性，特别是在那些胚系不是从体细胞突变中分离出来的生物体中。传统的观点认为，性通过创造遗传多样性来增强健康，这种观点在苔藓植物中可能是不合适的。这项研究的长期目标是检验体细胞非生殖细胞突变作为遗传变异的一个来源，可能等同于或超过苔藓有性重组的可能性。在进行此类调查之前，需要提供某些背景信息。这项研究计划补助金将允许金默尔博士完成初步研究，并开发支持长期目标的方法。这里提出的活动构成了一项重大研究工作的必要准备。

The evolutionary significance of sex is a central problem in evolutionary ecology. There has been a proliferation of models which predict the relative benefits of sexual vs. asexual reproduction but few empirical tests exist. The goal of this research is to provide just such a test, using the forest bryophyte, Tetraphis pellucida. Bryophytes are ideal systems in which to test hypotheses concerning the effectiveness of sexual or asexual reproduction in different environments since they exhibit a high degree of habitat specificity and wide array of reproductive modes. It has been demonstrated that levels of genetic variability in some asexual species are equivalent to those of sexual species. Asexual reproduction does not necessarily yield reduced genetic variability, especially in those organisms in which the germ line is not isolated from somatic mutation. The traditional view that sex enhances fitness through the creation of genetic diversity may be inappropriate in bryophytes. The long-term goal of this research is to examine the possibility that somatic non-germ cell mutation, as a source of genetic variability, may equal or exceed that of sexual recombination in mosses. Certain background information is required prior to such an investigation. This Research Planning Grant would permit Dr. Kimmerer to complete preliminary studies and to develop methods which would support the long-term goal. The activities proposed here constitute essential preparation for a major research effort.