COLLABORATIVE RESEARCH: Genetics and Development of Parallel Pollination System Evolution in Penstemon

这个项目考察了进化变化的可预测性程度。特别是，它将检验这样一个假设，即进化出相似特征的不同物种是通过相同基因的变化来实现这一点的。这一假说将用盆花属植物中的物种来验证，这些植物已经独立地进化出一套类似的花特征(例如，细长的花、增加的花蜜产量、延长的生殖器官)，以响应蜂鸟的授粉。如果这一假设是正确的，那么在不同的蜂鸟授粉物种中，影响特定特征的基因应该位于基因组中的相似位置。该项目将使用遗传和基因组方法对四种由蜂鸟授粉的物种和由蜜蜂授粉的密切相关物种进行测试。此外，这项研究将确定特征变化的发育基础(例如细胞大小或细胞增殖的变化)。在检验主要假设的过程中，该项目将对三个彭斯敦物种的基因组进行排序，并提供遗传图谱。这些资源将提供给科学界。该项目将为一名博士后和几名研究生提供分子和基因组技术以及生物信息学和统计分析方面的培训。最后，它将通过实习和独立学习，向本科生介绍进化生物学和基因组学科学，重点是少数族裔学生的参与。该项目考察了不同等级水平(发育和遗传)、授粉综合征内不同性状类型(数量和质量性状)以及适应蜂鸟授粉的不同花朵来源之间的平行关系。通过这样做，它将提供第一个专门设计的广泛数据，以确定由多个数量性状组成的复杂多性状综合征的并行表型进化在多大程度上由平行的遗传和发育机制进化。代表从蜜蜂传粉到蜂鸟传粉花综合征的四个独立转变的半茎植物物种对将为本研究提供基础。对于四个物种对中的每一个，将评估导致不同蜜蜂和蜂鸟适应的花形态的发育差异，以确定差异是否反映了平行的发展过程。对于相同的四个物种对，将使用遗传作图和基因组测序相结合的方法来评估在独立向蜂鸟授粉的转变中识别的数量花性状基因座是否对应于包含相同一组同源候选基因的同源基因组区域，这表明平行关系延伸到了遗传水平。由于很少有研究检验数量性状的遗传平行度，该项目包括开发一种新的“遗传平行度评分”，以量化数量和质量性状的遗传平行度。最后，通过量化来自图谱研究的遗传系中的发育参数，该项目将通过确定蜜蜂和蜂鸟适应的物种之间固定的遗传差异如何改变导致花卉特征不同的特定发育过程，将遗传和发育过程联系起来。

This project examines the extent to which evolutionary change is predictable. In particular, it will test the hypothesis that different species that evolve similar characteristics do so by changes in the same genes. This hypothesis will be examined using species in the plant genus Penstemon that have independently evolved a similar suite of floral characters (e.g. long, narrow flowers, increased nectar production, lengthening of the reproductive organs) in response to pollination by hummingbirds. If this hypothesis is true, then in different hummingbird-pollinated species, genes affecting a given character should be located at similar positions in the genome. The project will test this expectation using genetic and genomic approaches applied to four hummingbird-pollinated species and closely related species pollinated by bees. In addition, this research will determine the developmental basis (e.g. changes in cell size or cell proliferation) for the character changes. In examining the main hypothesis, the project will sequence the genomes of three Penstemon species and provide genetic maps. These resources will be made available to the scientific community. The project will provide training for one postdoc and several graduate students in molecular and genomic techniques, as well as in bioinformatics and statistical analysis. Finally, it will introduce undergraduate students to the sciences of evolutionary biology and genomics through internships and independent study with the PI and co-PI of the project, with a focus on minority student participation.This project examines parallelism across different hierarchical levels (developmental vs. genetic), across different trait types within the pollination syndrome (quantitative vs. qualitative traits), and across different origins of flowers adapted to hummingbird pollination. In doing so, it will provide the first extensive data specifically designed to determine the extent to which parallel phenotypic evolution of a complex multi-trait syndrome, comprised of multiple quantitative characters, evolved by parallel genetic and developmental mechanisms. Penstemon species pairs representing four independent transitions from bee to hummingbird pollination floral syndromes will provide the foundation of this research. For each of the four species pairs, the developmental differences that lead to divergent bee and hummingbird-adapted floral morphologies will be assessed to determine whether differences reflect parallel developmental processes. For the same four species pairs, genetic mapping combined with genome sequencing will be used to assess whether quantitative floral trait loci identified in independent transitions to hummingbird pollination correspond to homologous genomic regions containing the same set of homologous candidate genes, suggestive that parallelism extends to the genetic level. As few studies have examined genetic parallelism in quantitative traits, the project includes the development of a novel 'genetic parallelism score' to quantify the degree of genetic parallelism for both quantitative and qualitative traits. Lastly, by quantifying developmental parameters in genetic lines derived from the mapping study, the project will link genetic and developmental processes by determining how fixed genetic differences between bee- and hummingbird-adapted species alter the specific developmental processes that contribute to divergent floral traits.