Collaborative Research: The Evolution of Heterostylous Breeding Systems in Populations of Oxalis Alpina in the Sky Islands of the United States and Mexico

育种系统决定了个体如何聚集在一起繁殖，并影响种群中遗传多样性的数量和物种形成的潜力。植物提供了模型系统的理解因素，促进繁殖系统的变化，因为它们的生殖系统的变异性。在异型花柱中，独特的花型与化学不相容性有关，这种不相容性通常会阻止相似形式之间的交配，并促进形式之间的杂交（异交）。紫叶酢浆草似乎正在发展一种新的育种系统，在某些种群中失去了一种花型。为了测试先前的模型表明，自交不亲和性的变化是负责育种系统的进化，将进行杂交，以确定是否在不亲和性的变化是更常见的种群中，异型性更高度修改。将测量异交率，因为更大的自交亲和性可以延缓变体的损失。将测量不同变体内部和之间杂交的后代的相对适合度，以了解近交衰退在这种育种系统变化中的重要性。研究将集中于发生在贯穿墨西哥、亚利桑那州和新墨西哥州的山脉中的高山酢浆草种群。这项研究提供了对植物育种系统和一般生殖系统修改的进化因素的深入了解。该研究促进了国际合作，来自美国和墨西哥机构的教师，研究生和本科生的参与。该项目得到了国际科学和工程办公室的支持。

Breeding systems determine how individuals get together to reproduce, and influence the amount of genetic diversity in populations and the potential for speciation. Plants provide model systems for understanding factors promoting changes in breeding systems because of their variability in reproductive systems. In heterostyly, distinctive floral forms are associated with chemical incompatibilities that usually prevent mating between similar forms and promote crossing between forms (outcrossing). Oxalis alpina appears to be evolving a new breeding system, with loss of one floral morph in some populations. To test previous models indicating that changes in self-incompatibility are responsible for breeding system evolution, crosses will be carried out to determine whether changes in incompatibility are more common in populations where heterostyly is more highly modified. Outcrossing rates will be measured because greater self-compatibility could retard loss of morphs. The relative fitness of offspring from crosses within and between different morphs will be measured to understand the importance of inbreeding depression in this breeding system change. Research will focus on populations of Oxalis alpina occurring in mountain ranges extending through Mexico, Arizona, and New Mexico.This research provides insights into evolutionary factors that underlie modifications of plant breeding systems, and reproductive systems in general. The research fosters an international collaboration, with participation of faculty, graduate students, and undergraduates from U.S. and Mexican institutions. This project is being supported by the Office of International Science and Engineering.