Phylogeographic and population genetic analyses of Cucurbita moschata reveal divergence of two mitocondrial lineages linked to an elevational gradient

Periodo de realización: 1900/01/01 al 2020/01/01

Tipo: Artículo científico

Lugar(es) de estudio: México
Resumen: "Premise of the study: Cultivated pumpkins and squashes (Cucurbita) are of worldwide economic importance. Cucurbita moschata is the third major crop species in the genus. In Mexico it is known as “calabaza de castilla” and it is widely distributed and used. Research about its genetic diversity, population structure and phylogeography is still limited. Our aim was to understand how geography and elevation shape the distribution of genetic diversity of C. moschata landraces in Mexico based on chloroplast, mitochondrial and nuclear data. Methods: We sampled fruits from 24 localities throughout Mexico. We studied phylogeographic relationships among localities performing a haplotype network with mitochondrial DNA sequences. Furthermore, we analyzed levels of genetic variation and explored genetic structure with cluster analysis using eleven nuclear microsatellite loci. Key results: Cucurbita moschata shows very low cpDNA diversity. We found relatively high genetic diversity and intermediate genetic differentiation among localities for both the mtDNA and nuclear microsatellite loci and relatively high levels of inbreeding for each locality. Two mitochondrial lineages are in agreement with an elevation gradient (highlands vs. lowlands), while nuclear genetic data suggest that the localities from the Yucatan Peninsula constitute a well-differentiated group. Conclusions: Divergence between two mitochondrial lineages is linked to an elevational gradient (highlands and lowlands), which relates to a wide geographical-altitudinal distribution of C. moschata. The Isthmus of Tehuantepec might be a partial barrier to gene flow between Continental Mexico landraces and the Yucatan Peninsula landraces."

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