Morphophysiological variation in some Mexican species of vegetable Amaranthus: Evolutionary tendencies under domestication

Amaranth (Amaranthus spp.) is an important food resource for indigenous peoples of Mexico. Grain-producing species are mostly cultivated plants, while the species used as vegetables are commonly encouraged in maize plots. Notable biological differences exist between these two types of amaranths, This study analyzes the morphophysiological variation in some Mexican species of Amaranthus and its relationship to the use and management of this taxa. A sample of individuals grown from 14 field collections representing 3 species and putative hybrid derivatives were grown in experimental plots and 18 morphological and physiological characters were measured. A statistical multivariate analysis was performed on these data. The results show that the grain-producing plants tend to allocate a high proportion of energy to the production of inflorescences while the plants used as vegetables allocate a higher proportion of biomass to the foliage. This suggests that domestication of Mexican species of Amaranthus have taken two different evolutionary paths depending upon the form of use and management by humans.