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

这个项目考察了进化变化可预测的程度。特别是，它将检验这样一个假设，即不同的物种进化出相似的特征是通过改变相同的基因来实现的。这一假设将被检验，使用的是在蜂鸟的授粉下独立进化出一套相似的花特征（例如，长而窄的花，增加的花蜜产量，延长的生殖器官）的pentstemon植物属的物种。如果这个假设是正确的，那么在不同的蜂鸟授粉物种中，影响特定性状的基因应该位于基因组中的相似位置。该项目将对四种蜂鸟授粉的物种和由蜜蜂授粉的密切相关的物种采用遗传和基因组方法来验证这一预期。此外，本研究将确定性状变化的发育基础（如细胞大小或细胞增殖的变化）。在检验主要假设的过程中，该项目将对三种盆草的基因组进行测序，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，并与项目的PI和co-PI合作，重点是少数民族学生的参与。该项目研究了不同层次（发育与遗传）、授粉综合征中不同性状类型（数量与质量性状）以及适应蜂鸟授粉的不同来源的花的并行性。在此过程中，它将提供第一个专门设计的广泛数据，以确定由多个数量特征组成的复杂多性状综合征的平行表型进化在多大程度上由平行遗传和发育机制进化而来。代表蜜蜂传粉到蜂鸟传粉四种独立过渡的盆草种对将为本研究提供基础。对于四对物种中的每一对，将评估导致不同的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平行的发育过程。对于相同的四对物种，遗传作图结合基因组测序将评估在独立过渡到蜂鸟授粉过程中发现的数量花性状位点是否对应于包含同一组同源候选基因的同源基因组区域，这表明平行性已经扩展到遗传水平。由于很少有研究检查数量性状的遗传平行性，该项目包括开发一种新的“遗传平行度评分”，以量化数量性状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的发育参数，该项目将通过确定适应蜜蜂和蜂鸟的物种之间的固定遗传差异如何改变导致不同花性状的特定发育过程，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.