Department of Plant Sciences, University of California One Shields Avenue, Davis, California, 95616.
Department of Ecology and Evolutionary Biology, University of California Santa Cruz, California, 95064 ; Smithsonian Tropical Research Institute Apartado, 0843-03092, Balboa, Republic of Panama.
Ecol Evol. 2014 Mar;4(5):539-53. doi: 10.1002/ece3.948. Epub 2014 Jan 28.
Species in the early stages of domestication, in which wild and cultivated forms co-occur, provide important opportunities to develop and test hypotheses about the origins of crop species. Chrysophyllum cainito (Sapotaceae), the star apple or caimito, is a semidomesticated tree widely cultivated for its edible fruits; it is known to be native to the neotropics, but its precise geographic origins have not been firmly established. Here, we report results of microsatellite marker analyses supporting the hypothesis that the center of domestication for caimito was the Isthmus of Panama, a region in which few crop species are believed to have originated, despite its importance as a crossroads for the dispersal of domesticated plants between North and South America. Our data suggest that caimito was domesticated in a geographically restricted area while incorporating a diverse gene pool. These results refute the generally accepted Antillean origin of caimito, as well as alternative hypotheses that the species was domesticated independently in the two areas or over a broad geographic range including both. Human-mediated dispersal from Panama to the north and east was accompanied by strong reductions in both genotypic and phenotypic diversity. Within Panama, cultivated and wild trees show little neutral genetic divergence, in contrast to striking phenotypic differentiation in fruit and seed traits. In addition to providing a rare example of data that support the hypothesis of a narrow geographic origin on the Isthmus of Panama for a now widespread cultivated plant species, this study is one of the first investigations of the origins of an edible species of the large pantropical family Sapotaceae.
处于驯化早期阶段的物种，其中野生和栽培形式并存，为发展和测试关于作物物种起源的假说提供了重要机会。人心果（山榄科），也被称为星苹果或 caimito，是一种半驯化的树，因其可食用的果实而广泛种植；已知原产于新热带地区，但确切的地理起源尚未确定。在这里，我们报告了微卫星标记分析的结果，支持了这样的假设，即人心果的驯化中心是巴拿马地峡，尽管它是南北美洲驯化植物传播的交汇点，但该地区很少有作物物种起源。我们的数据表明，人心果是在一个地理上受限制的地区被驯化的，同时融入了多样化的基因库。这些结果反驳了人心果通常被认为起源于安的列斯群岛的观点，以及该物种在两个地区或包括两者在内的广泛地理范围内独立驯化的替代假说。人类从中美洲地峡向北和向东的传播伴随着基因型和表型多样性的强烈减少。在巴拿马境内，栽培和野生树木之间几乎没有中性遗传分歧，而果实和种子特征上的表型分化却非常显著。除了为一个现在广泛种植的栽培植物物种在巴拿马地峡的狭窄地理起源假说提供了罕见的数据支持外，这项研究还是对大泛热带山榄科可食用物种起源的首次研究之一。
