DISSERTATION RESEARCH: Evolution and domestication genetics of the mango

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The mango was first domesticated in India more than 4,000 years ago. Today, mangoes are grown on six continents and are one of the world's most important tropical fruits. In the face of climate change and a growing human population, agriculture must strive to improve crop yields while facing new and variable climatic conditions. Traits to deal with these stressors, like drought tolerance and disease resistance, can be introduced into crops through crop breeding programs. Although hundreds of plant species have undergone domestication, many concepts about the impacts of domestication on genetic diversity have come from research focusing on short-lived crops like maize and rice. This focus has left gaps in our knowledge about domestication in other plant species, such as fruit trees. During the process of domestication, many crops lose genetic diversity, which can result in the unintentional loss of beneficial traits that could be useful for agriculture. However, some evidence that suggests long-lived plants, like fruit trees, may be less susceptible to the negative impacts of domestication. This project will build on recent efforts to expand scientific insight into the domestication of non-staple crops by providing a basic understanding of the evolutionary history of the mango, and will lay the groundwork for future breeding programs to improve its agricultural qualities. Following its original domestication, the mango, Mangifera indica L. (Anacardiaceae), was dispersed throughout the tropics and warm subtropics. However, the eastward and westward migrations of Mangifera indica may have had strikingly different effects on the genetic structure and diversity of cultivated mango. During its journey westward through Africa and on to the Americas, Mangifera indica suffered a series of population bottlenecks, suggesting that a limited amount of the crop's genetic diversity reached the New World. Conversely, eastward expansion into Southeast Asia brought it into contact with more than 35 other Mangifera species. Morphological evidence and preliminary genetic data indicate that the genetic diversity of M. indica in SE Asia may have been bolstered by gene flow from these wild relatives. This research will use double digest restriction site associated DNA (ddRAD) sequencing to investigate genetic diversity, population differentiation, and hybridization in 192 Mangifera accessions cultivated at Botanic Gardens around the world, including 116 M. indica cultivars of known geographic origin and 76 accessions from four other regionally-cultivated Mangifera species.