Blancas J., Casas A., Lira R., Caballero J., Traditional Management and Morphological Patterns of Myrtillocactus schenckii (Cactaceae) in the Tehuacán Valley, Central Mexico, Economic Botany, 2009, 63(4):375-387, doi: 10.1007/s12231-009-9095-2
The study combines interviews about plant use with comparisons of wild populations, plants retained in agricultural systems and plants cultivated in gardens. Local people selected, among other traits, abundant fruit production and preserved desirable plants during land conversion. Cultivated populations differed in fruit size and number, whereas sugar content did not differ significantly among management types. The authors interpret this pattern as an early stage of domestication.