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

繁育系统决定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，用于了解促进繁殖系统变化的因素，因为它们在生殖系统中具有变异性。在异型花柱中，独特的花型与化学不亲和性有关，这种不亲和性通常会阻止相似类型之间的交配，并促进不同类型之间的杂交(异交)。高山草草似乎正在进化一种新的繁殖系统，在一些种群中失去了一个花形态。为了测试以前的模型，这些模型表明自交不亲和性的变化是导致育种系统进化的原因，将进行杂交，以确定不亲和性的变化是否在异型花柱高度修饰的群体中更常见。异交率将被测量，因为更大的自交亲和性可能会延缓形态的丧失。将测量不同变型内和不同变型之间杂交后代的相对适合度，以了解近亲交配衰退在这一繁殖系统变化中的重要性。这项研究将集中在分布在墨西哥、亚利桑那州和新墨西哥州的山脉中的高山紫草种群。这项研究提供了对植物育种系统和一般生殖系统修改背后的进化因素的见解。这项研究促进了国际合作，来自美国和墨西哥机构的教职员工、研究生和本科生参与其中。该项目得到了国际科学与工程办公室的支持。

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.