SG: Is Pollinator Discrimination Among Populations of the Southwestern Desert Creosote Bush Differing in Chromosome Number Promoting Speciation?

本研究将通过研究荒漠灌木杂色灌木(Larrea Tridentata)中传粉者的喜好和染色体组成不同的植物之间的生殖交互作用，来研究多倍体在开花植物多样性中的作用。确定一个物种变成两个物种的过程对于了解生物多样性的模式和生态系统的功能至关重要。物种形成是新物种形成的过程，当种群或群体之间的繁殖障碍演变时就会发生。然而，研究具有多个染色体组的开花植物物种的物种形成--一种被称为多倍体的情况--被证明是困难的。大多数开花植物是多倍体的，具有不同染色体数目的群体不容易杂交，但它们很少被认为是不同的物种。造成这一现象的原因很多，从不同染色体数目的植物之间的物理相似性，到它们是否适应了不同的环境。尽管具有不同染色体互补的杂色灌木生活在生态上截然不同的区域，但它们有时会共存，这表明额外的生殖障碍是导致分化的原因。通过结合DNA分析、温室实验和田间调查，该项目将为具有不同染色体互补的植物群体提供前所未有的物种形成早期阶段的洞察。该研究的总体目标是通过阐明基因组复制对植物多样性的生物学意义，将多倍体物种纳入物种形成研究的更大范围。多倍体，特别是同源多倍体，基因组复制发生在一个谱系内，而不是通过杂交，这给进化生物学家带来了许多挑战，包括理解生态和内在遗传过程对多样性的相对重要性。种群水平的分析对于评估动植物相互作用和生态适应如何影响染色体组成不同的种内群体之间的差异，以及多倍体物种的多样性是否类似于模式二倍体物种至关重要。此外，该项目侧重于北美敏感荒漠生物群中的关键植物物种三齿水母及其本土传粉者，将有助于表征新的分子多样性和生态相互作用，包括隐蔽的多倍体物种的生物多样性。对染色体组成不同的种群的分类识别可能会显著改变世界某些地区的生物多样性估计，特别是温带生物群，影响我们对主要生态模式的理解。

This research will investigate the role of polyploidy in flowering plant diversification by studying pollinator preferences and reproductive interactions between plants differing in chromosome complement in the desert shrub creosote bush (Larrea tridentata). Determining the processes by which one species becomes two is crucial to understanding patterns of biodiversity and the functioning of ecosystems. Speciation, the process of new species formation, occurs when barriers to reproduction evolve between populations or groups. However, studying speciation for flowering plant species with multiple chromosome sets - a condition known as polyploidy - has proven difficult. Most flowering plants are polyploid, and groups with different chromosome numbers cannot easily interbreed, yet they are rarely recognized as different species. Reasons for this range from the physical similarity between plants with different chromosome numbers, to whether they have adapted to different environments. Although creosote bush with different chromosome complements inhabit ecologically distinct areas, they sometimes co-occur suggesting additional reproductive barriers are responsible for divergence. By combining DNA analyses, greenhouse experiments, and field investigations, this project will provide unprecedented insight into the early stages of speciation for groups of plants with different chromosome complements.The overarching goal of this research is to bring polyploid species under the larger umbrella of speciation research by elucidating the biological significance of genome duplication to plant diversification. Polyploidy, especially autopolyploidy, where genome duplication occurs within a lineage rather than through hybridization, poses many challenges for evolutionary biologists, including understanding the relative importance of ecological and intrinsic genetic processes to diversification. Population-level analyses are critical for evaluating how plant-animal interactions and ecological adaptation influence divergence among "intraspecific" groups differing in chromosome complement, and whether diversification of polyploid species is similar to model diploid species. Moreover, this project, focused on the keystone plant species Larrea tridentata and its native pollinators in sensitive North American desert biomes, will help characterize the novel molecular diversity and ecological interactions comprising the cryptic biodiversity of polyploid species. The taxonomic recognition of populations differing in chromosome complement could significantly alter biodiversity estimates for certain parts of the world, especially temperate biomes, impacting our understanding of major ecological patterns.