Data from: Human management and hybridization shape treegourd fruits in the Brazilian Amazon Basin

Local people's perceptions of cultivated and wild agrobiodiversity, as well as their management of hybridization are still understudied in Amazonia. Here we analyze domesticated treegourd (Crescentia cujete), whose versatile fruits have technological, symbolic and medicinal uses. A wild relative (C. amazonica) of the cultivated species grows spontaneously in Amazonian flooded forests. We demonstrated, using whole chloroplast sequences and nuclear microsatellites, that the two species are strongly differentiated. Nonetheless, they hybridize readily throughout Amazonia and the proportions of admixture correlate with fruit size variation of cultivated trees. New morphotypes arise from hybridization, and are recognized by people and named as local varieties. Small hybrid fruits are used to make the important symbolic rattle (maracá), suggesting that management of hybrid trees is an ancient human practice in Amazonia. Effective conservation of Amazonian agrobiodiversity needs to incorporate this interaction between wild and cultivated populations that is managed by smallholder families. Beyond treegourd, our study clearly shows that hybridization plays an important role in tree crop phenotypic diversification, and that the integration of molecular analyses and farmers'perceptions of diversity help disentangle crop domestication history.

在亚马逊地区，当地民众对栽培与野生农业生物多样性的认知，以及他们对杂交现象的管理方式，迄今仍未得到充分研究。本研究聚焦于驯化的葫芦树（Crescentia cujete），其果实用途广泛，兼具工艺、象征与药用价值。该栽培物种的野生近缘种亚马逊葫芦树（C. amazonica）自然生长于亚马逊季节性淹水林中。我们通过全叶绿体基因组序列与核微卫星标记分析证实，这两个物种存在显著遗传分化。尽管如此，二者在整个亚马逊地区均可自然杂交，其遗传混合比例与栽培植株的果实大小变异呈显著相关。杂交可产生新的形态型，当地民众能够识别这些形态型并将其命名为地方品种。小型杂交果实可用于制作极具象征意义的马拉卡摇铃（maracá），这表明管理杂交植株是亚马逊地区源远流长的人类实践活动。有效保护亚马逊农业生物多样性，需纳入由小农家庭管理的野生与栽培种群间的这种互作关系。除葫芦树之外，本研究还明确证实：杂交在木本作物的表型多样化过程中发挥着关键作用；而将分子分析与农户对多样性的认知相结合，有助于厘清作物驯化的历史脉络。