title: Genetic structure of coexisting wild and managed agave populations: implications for the evolution of plants under domestication.
abstract: Domestication is a continuous evolutionary process guided by humans. This process leads to divergence in characteristics such as behaviour, morphology or genetics, between wild and managed populations. Agaves have been important resources for Mesoamerican peoples since prehistory. Some species are domesticated and others vary in degree of domestication. Agave inaequidens Koch is used in central Mexico to produce mescal, and a management gradient from gathered wild and silvicultural populations, as well as cultivated plantations, has been documented. Significant morphological differences were reported among wild and managed populations, and a high phenotypic variation in cultivated populations composed of plants from different populations. We evaluated levels of genetic diversity and structure associated with management, hypothesizing that high morphological variation would be accompanied by high genetic diversity in populations with high gene flow and low genetic structure among managed and unmanaged populations. Wild, silvicultural and cultivated populations were studied, collecting tissue of 19-30 plants per population. Through 10 nuclear microsatellite loci, we compared population genetic parameters. We analysed partition of variation associated with management categories to estimate gene flow among populations. Agave inaequidens exhibits high levels of genetic diversity (He = 0.707) and moderate genetic structure (FST = 0.112). No differences were found in levels of genetic diversity among wild (He = 0.704), silviculturally managed (He = 0.733) and cultivated (He = 0.698) populations. Bayesian analysis indicated that five genetic clusters best fit the data, with genetic groups corresponding to habitats where populations grow rather than to management. Migration rates ranged from zero between two populations to markedly high among others (M = 0.73-35.25). Natural mechanisms of gene flow and the dynamic management of agave propagules among populations favour gene flow and the maintenance of high levels of variation within all populations. The slight differentiation associated with management indicates that domestication is in an incipient stage.
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán 58190, Mexico.
authors.forename: Carmen Julia
authors.initials: CJ
authors.lastname: Figueredo
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán 58190, Mexico acasas@cieco.unam.mx.
authors.forename: Alejandro
authors.initials: A
authors.lastname: Casas
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán 58190, Mexico.
authors.forename: Antonio
authors.initials: A
authors.lastname: González-Rodríguez
authors.affiliation: Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Carretera Panamericana km 11, Apdo. 20632, Altos de Pipe, Miranda 1020-A, Venezuela.
authors.forename: Jafet M
authors.initials: JM
authors.lastname: Nassar
authors.affiliation: Centro de Investigación Científica de Yucatán, A.C. Calle 43 No. 130, Colonia Chuburná de Hidalgo, CP 97200 Mérida, Yucatán, México.
authors.forename: Patricia
authors.initials: P
authors.lastname: Colunga-GarcíaMarín
authors.affiliation: Instituto de Investigaciones en Ecosistemas y Sustentabilidad, Universidad Nacional Autónoma de México, Campus Morelia, Apartado Postal 27-3 (Santa María de Guido), Morelia, Michoacán 58190, Mexico.
authors.forename: Víctor
authors.initials: V
authors.lastname: Rocha-Ramírez
keywords: Agave inaequidens; Agaves; conservation genetics; domestication; genetic structure; genetic variation; microsatellites