Growth Patterns in Seedling Roots of the Pincushion Cactus Reveal Trends of Intra- and Inter-Specific Variation.

Genetic mechanisms controlling root development are well-understood in plant model species, and emerging frontier research is currently dissecting how some of these mechanisms control root development in cacti. Here we show the patterns of root architecture development in a gradient of divergent lineages, from populations to species in . First, we show the patterns of variation in natural variants of the species . Then we compare this variation to closely related species within the Series in (diverging for the last 2.1 million years) in which is inserted. Finally, we compared these patterns of variation to what is found in a set of species belonging to different Series (diverging for the last 8 million years). When plants were grown in controlled environments, we found that the variation in root architecture observed at the intra-specific level, partially recapitulates the variation observed at the inter-specific level. These phenotypic outcomes at different evolutionary time-scales can be interpreted as macroevolution being the cumulative outcome of microevolutionary phenotypic divergence, such as the one observed in accessions and species.