The domestication of perennials is less well-known than the domestication of annual crops. Citrus is one of the most important fruit crops worldwide, growing in more than 114 countries. Citrus domestication is believed to have begun much more recently than the domestication of food crops, ca. 4000 years ago. Genetic evidence for mandarin domestication is lacking so far. Mandarin is a basal and founder species in the citrus family. Many other commercial varieties such as the sweet orange, grapefruit, and...