Morphological and genetic divergence between Agave inaequidens, A. cupreata and the domesticated A. hookeri. Analysis of their evolutionary relationships

Abstract

Agave inaequidens and A. cupreata are wild species with some populations under incipient management, while A. hookeri is exclusively cultivated, used for producing the fermented beverage pulque. These species are closely related and sympatric members of the Crenatae group, but taxonomists have previously hypothesized that A. inaequidens is the most probable ancestor of A. hookeri. Our study aims at evaluating patterns of morphological and genetic divergence among populations of the three species, in order to analyze their ecological and possible evolutionary relationships. We studied 24 agave populations, 16 of them of Agave inaequidens, four of A. cupreata and four of A. hookeri. Population morphometric and genetics studies were performed using 39 morphological characters and 10 nuclear microsatellites, respectively. We estimated levels of morphological and genetic diversity and dissimilarity, as well as genetic structure and gene flow among populations and species. The three species were clearly differentiated by general plant size, lateral teeth, terminal spines, flowers and fruit size. The largest plants were those of A. hookeri followed by A. inaequidens and the smallest were A. cupreata. Multivariate analyses indicated greater morphological similarity between A. hookeri and cultivated A. inaequidens, while A. cupreata consistently appeared as a separate group. We identified similar levels of morphological diversity index (MDI) in the three species, but higher genetic diversity in A. inaequidens (MDI = 0.401–0.435; HE = 0.704–0.733), than in A. cupreata (MDI = 0.455–0.523; HE = 0.480–0.510) and the predominantly vegetative propagated crop A. hookeri (MDI = 0.335–0.688; HE = 0.450–0.567), a pattern consistent with our expectations. The morphological and genetic similarities between cultivated A. inaequidens and A. hookeri support the hypothetical evolutionary relationships among these species, but studies with cpDNA and SNPs, and including other member of the Crenatae group are necessary to further resolve these relationships.

Morphological Diversity and Genetic Relationships in Pulque Production Agaves in Tlaxcala, Mexico, by Means of Unsupervised Learning and Gene Sequencing Analysis

“…The analysis of reproductive, biochemical, and genetic characters could improve the taxonomic resolution of the different landraces. Figueredo et al (2014Figueredo et al ( , 2017 analyzed vegetative, reproductive, and genetic characters, distinguishing wild populations of A. inaequides from cultivated ones as well as species such as A. hookeri and A. cupreata. Few studies have analyzed reproductive characters due to the difficulty of obtaining flowers, fruits, and seeds from pulque agaves.…”

Sociopolitical organization, landscape change, and hydraulic engineering in the Teotihuacan Valley, Mexico: 1250 B.C.–A.D. 1810

“…Morphometric and genetic studies of this xerophytic crop suggest that it was domesticated in garden settings, with humans selecting large individuals with desirable traits then transporting them to house gardens (Figueredo-Urbina, Casas, & Torres-García, 2017). Ethnographic and genetic observations of xerophytic use (maguey and nopal) in Mexico show that people also select for variability in plant phenology to ensure year-round availability of the desired goods (Chávez-Moreno, Tecante, & Casas, 2009;Figueredo-Urbina et al, 2017;Pimienta-Barrios, 1994;Reyes-Agüero, Rivera, & Flores, 2005).…”

“…Morphometric and genetic studies of this xerophytic crop suggest that it was domesticated in garden settings, with humans selecting large individuals with desirable traits then transporting them to house gardens (Figueredo-Urbina, Casas, & Torres-García, 2017). Ethnographic and genetic observations of xerophytic use (maguey and nopal) in Mexico show that people also select for variability in plant phenology to ensure year-round availability of the desired goods (Chávez-Moreno, Tecante, & Casas, 2009;Figueredo-Urbina et al, 2017;Pimienta-Barrios, 1994;Reyes-Agüero, Rivera, & Flores, 2005). Selection for multiple uses (cloth, tool, and hydration) during multiple times of year seems unique to Mesoamerican xerophytic domestication, and has led to a surprising degree of genetic diversity even in the most highly domesticated species and cultivars such as Allium hookeri, a variant absent from the wild (Figueredo-Urbina et al, 2017).…”

Consequences of Traditional Management in the Production and Quality of Copal Resin (Bursera bipinnata (Moc. & Sessé ex DC.) Engl.) in Mexico

“…Mesoamerica is the cultural region comprised from southern Mexico to northern Costa Rica [1], which has contributed to humanity through important crops, plant management strategies, and plant diversification through domestication [2][3][4]. The agricultural and silvicultural management of plant populations have promoted morphological, physiological, genetic, and phytochemical diversification in features of human interest [5][6][7][8][9][10], compared with unmanaged or incipiently managed populations [11]. Silvicultural management, also referred to as in situ management, can include the collection, tolerance, promotion, and protection of some individuals with desirable attributes in wild vegetation, agroforestry systems, fallow areas, and other anthropized zones [4,5,8,[11][12][13].…”