Long-term Natural Selection and Adaptive Introgression in Weedy Sunflowers

杂交(不同物种之间的交配和异花受精)是一种普遍的自然现象，但它在进化中的作用仍存在争议。它是不是一种不适应的力量，通常会导致像骡子这样的不育、死胡同的个体？或者，它是否定期对适应和进化多样化做出贡献？提出了一种新的方法来比较实验混合控制线和非混合控制线在现场的长期进化变化。这些杂交品系旨在重现古代自然杂交的早期阶段，是通过与一种经过充分研究的野生向日葵的亲本杂交而产生的。杂交是否可以提高适应和表型变化的速度将通过跟踪杂交群体和对照群体5-10代的适应度、性状和数量性状基因座(QTL)来检验。通过比较普通花园中的线条，将进化变化与表型可塑性区分开来。杂交种系统变化的长期可预测性将通过评估实验杂交种是否在它们被模拟的自然杂交种上收敛表型和基因型态来检验。拟议的研究是第一个检验杂交对野生(非作物)系统中多个世代适应进化的影响的试验田研究。这笔赠款支持的研究将通过年度推广计划和面向小学生的向日葵教学模块，影响K-12和大学层面的科学教育。该项目将通过培养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。根据国际和平研究所实验室目前的人口情况，参与这项资助的学生中，超过一半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.