title: The influence of climatic niche preferences on the population genetic structure of a mistletoe species complex.
abstract: The prevalent view on genetic structuring in parasitic plants is that host-race formation is caused by varying degrees of host specificity. However, the relative importance of ecological niche divergence and host specificity to population differentiation remains poorly understood. We evaluated the factors associated with population differentiation in mistletoes of the Psittacanthus schiedeanus complex (Loranthaceae) in Mexico. We used genetic data from chloroplast sequences and nuclear microsatellites to study population genetic structure and tested its association with host preferences and climatic niche variables. Pairwise genetic differentiation was associated with environmental and host preferences, independent of geography. However, environmental predictors appeared to be more important than host preferences to explain genetic structure, supporting the hypothesis that the occurrence of the parasite is largely determined by its own climatic niche and, to a lesser degree, by host specificity. Genetic structure is significant within this mistletoe species complex, but the processes associated with this structure appear to be more complex than previously thought. Although host specificity was not supported as the major determinant of population differentiation, we consider this to be part of a more comprehensive ecological model of mistletoe host-race formation that incorporates the effects of climatic niche evolution.
authors.affiliation: Departamento de Biología Evolutiva, Instituto de Ecología, AC (INECOL), Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, Mexico.
authors.forename: Santiago
authors.identifier: http://orcid.org/0000-0003-3999-6952
authors.initials: S
authors.lastname: Ramírez-Barahona
authors.affiliation: CONACyT-Instituto de Investigaciones sobre los Recursos Naturales, Universidad Michoacana de San Nicolás de Hidalgo, Av. San Juanito Itzícuaro s/n, Nueva Esperanza, Morelia, Michoacán, 58330, Mexico.
authors.forename: Clementina
authors.initials: C
authors.lastname: González
authors.affiliation: Laboratorio de Genética de la Conservación, Instituto de Investigaciones en Ecosistemas y Sustentabilidad (IIES), UNAM, Antigua carretera a Pátzcuaro 8701, Ex Hacienda de San José de la Huerta, Morelia, Michoacán, 58190, Mexico.
authors.forename: Antonio
authors.initials: A
authors.lastname: González-Rodríguez
authors.affiliation: Departamento de Biología Evolutiva, Instituto de Ecología, AC (INECOL), Carretera antigua a Coatepec No. 351, El Haya, Xalapa, Veracruz, 91070, Mexico.
authors.forename: Juan Francisco
authors.initials: JF
authors.lastname: Ornelas
mesh_terms: D002980:Climate; D017753:Ecosystem; D005828:Genetics, Population; D006790:Host-Parasite Interactions; D028183:Loranthaceae / Q000502:physiology; D008800:Mexico; D018895:Microsatellite Repeats; D014784:Mistletoe / Q000235:genetics*
keywords: ecological niche; host-race formation; landscape genetics; microsatellites; parasites