Long-term Natural Selection and Adaptive Introgression in Weedy Sunflowers

杂交（不同物种之间的交配和交叉受精）是一种普遍存在的自然现象，但它在进化中的作用仍存在争议。它是一种不适应的力量，通常导致不育，像骡子一样没有出路的个体？或者它是否经常有助于适应和进化多样化？提出了一种比较田间试验杂交和非杂交控制系长期进化变化的新方法。这种杂交系旨在重现古代自然杂交的早期阶段，是通过杂交一种经过充分研究的野生向日葵的亲本而获得的。杂交是否能提高适应率和表型变化将通过在杂交群体和对照群体中跟踪5-10代的适应度、性状和数量性状位点（QTL）来检验。通过比较普通园林中的株系，将进化变化与表型可塑性区分开来。杂交系统变化的长期可预测性将通过评估实验杂交种是否在表型和基因表型上趋同于它们所建模的自然杂交种来检验。这项研究是第一次在野外实验中研究杂交对野生（非作物）系统多代适应性进化的影响。通过年度推广计划和面向小学生的向日葵教学模块，这项资助的研究将影响K-12和大学水平的科学教育。该项目将通过培训10名本科生、3名研究生和2名技术人员来整合研究和教育。根据目前PI实验室的人数，参与这项资助的学生中有一半以上将来自科学界代表性不足的群体。

Hybridization (mating and cross-fertilization between different species) is a widespread natural phenomenon, yet its role in evolution is still debated. Is it a maladaptive force, usually resulting in sterile, dead-end individuals like mules? Or does it regularly contribute to adaptation and evolutionary diversification? A novel approach is proposed that compares long-term evolutionary change in experimental hybrid and non-hybrid control lines in the field. The hybrid lines, intended to recreate the early stages of an ancient natural hybridization, are derived by crossing the parents of a well-studied wild sunflower. Whether hybridization can increase rates of adaptation and phenotypic change will be examined by tracking fitness, traits, and quantitative trait loci (QTL) in the hybrid and control populations over 5-10 generations. Evolutionary change will be distinguished from phenotypic plasticity by comparing the lines in common gardens. The long-term predictability of change in hybrid systems will be examined by assessing whether the experimental hybrids converge phenotypically and genotypically on the natural hybrid upon which they are modeled.The proposed research is the first experimental field study to examine the impact of hybridization on adaptive evolution over multiple generations in a wild (non-crop) system. The research supported by this grant will impact science education at the K-12 and university levels, through annual outreach programs and a sunflower teaching module for elementary school students. The project will integrate research and education by training ten undergraduate students, three graduate students, and two technicians. Based on the current population of the PI's lab, more than half of the students participating in this grant will be from underrepresented groups in the sciences.