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

José De Jesús González-Sánchez,Patricia Vélez,José Antonio Lara-González,Itzel Santiago-Sandoval,Cristian R Cervantes,Salvador Arias,Joel Colchado-López,Ulises Rosas,Jerónimo Reyes-Santiago

doi:10.3389/fpls.2021.750623

José De Jesús González-Sánchez, Patricia Vélez + Show 7 more

Open Access

https://doi.org/10.3389/fpls.2021.750623

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Abstract

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 Mammillaria. First, we show the patterns of variation in natural variants of the species Mammillaria haageana. Then we compare this variation to closely related species within the Series Supertexta in Mammillaria (diverging for the last 2.1 million years) in which M. haageana is inserted. Finally, we compared these patterns of variation to what is found in a set of Mammillaria 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 Mammillaria accessions and species.

Highlights

A long standing debate in evolutionary biology is whether the nature of macroevolutionary change can be explained based on the principles and processes of microevolution
To characterize the natural variation in developmental dynamics in a Mammillaria species, we chose M. haageana, a widely distributed species along the Mexican neovolcanic axis (Hunt et al, 2006; Arias et al, 2012), whose diversity we are currently characterizing (Cervantes et al, 2021), and we have established a collection of natural accessions at the Jardín Botánico (Instituto de Biología, UNAM)
One possibility is that the cumulative effects of microevolutionary processes within species give rise to the phenotypic diversity seen among species

Summary

Introduction

A long standing debate in evolutionary biology is whether the nature of macroevolutionary change can be explained based on the principles and processes of microevolution. One possibility is that the macroevolutionary outcomes are the result of the cumulative microevolutionary processes, so the footprint of microevolution can be seen at higher levels of taxonomic divergence. This possibility has been tested in some organisms such as crocodiles, in which intraspecific crane variation (a highly robust trait) spans half of the extant species (Okamoto et al, 2015). It has been argued that morphological divergence between species is often non-adaptive, as compared to variation within species This is because regardless of their adaptive value, phenotypic differentiation has been suggested to be frequently rapid, and random in direction, involving the evolution of gene regulation, pleiotropy, epistasis and canalization (Davis and Gilmartin, 1985), which in turn could result in different nature of the variation within and between species. We attempt to provide elements to this discussion in plant evolution, studying the root development of Mammillaria species

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