An Analysis of Hybrid Zone Dynamics in Iris

这项研究的目的是确定属于同一物种的个体之间以及属于两个不同物种的个体之间的杂交对蝴蝶花杂交群体的遗传结构和进化的影响。亲子关系分析(使用蛋白质和DNA标记)将被用来辨别自然发生的杂交种群和引入了六角异株藻个体的黄褐斑潜蝇种群中的基因交换模式。亲子关系分析还将允许估计花粉与种子流动对这两个种群遗传结构的影响。这些分析将被用来确定基因流对(I)两个物种之间的基因转移，(Ii)单个植物的繁殖成功和(Iii)杂交群体中彼此杂交的植物数量的影响。通过将每个物种和自然杂交种的种子播种到黄腐菌、六倍体和杂交种群体中，来评估自然选择对黄腐菌、六倍体及其天然杂交种的生存和繁殖的影响。因此，对不同物种和杂交品种的自然选择将通过记录萌发频率、开花存活、开花数量和总生物量来衡量。这些测量将允许计算不同栖息地类型中黄曲霉、六角叉尾轮虫和各种杂交类的相对适合度。然后，杂交种群中不同遗传标记的适合度估计、扩散测量和频率将被用于测试预测杂交种群特定进化结果的模型。

The aim of the proposed study is to determine the effect of crosses between individuals belonging to the same species and between individuals belonging to two different species on the genetic structure and evolution of hybrid populations of irises. Paternity analyses (using protein and DNA markers) will be used to discern patterns of gene exchange in a naturally occurring hybrid population and in an I. fulva population where I. hexagona individuals have been introduced. The paternity analysis will also allow an estimate of the impact of pollen versus seed movement on the genetic structure of these two populations. These analyses will be used to determine the affect of gene flow on (i) the transfer of genes between the two species, (ii) the reproductive success of individual plants and (iii) the number of plants that cross with one another in the hybrid populations. The effects of natural selection on the survival and reproduction of I. fulva, I. hexagona and their natural hybrids will be estimated by sowing seeds from each of the species and natural hybrids into I.fulva, I. hexagona and hybrid populations. Natural selection on the different species and hybrids will, thus be measured by recording germination frequencies, survival to flowering, numbers of flowers produced and the overall biomass produced. These measurements will allow the calculation of the relative fitness of I. fulva, I. hexagona and various hybrid classes in different habitat types. The estimates of fitness, measurements of dispersal and the frequencies of different genetic markers in the hybrid populations will then be used to test models that predict specific evolutionary outcomes for hybrid populations.