Search

Linum suffruticosum s.l. is a taxonomic complex widespread in the Western Mediterranean basin. The complex is characterized by a high phenotypic and cytogenetic diversity, and by a unique three-dimensional heterostyly system that makes it an obligate outcrosser. We studied the patterns of genetic diversity and structure of populations throughout the entire distribution of L. suffruticosum s.l. with microsatellite markers. We analysed their relationships with various biological and ecological variables, including the morph ratio and sex organ reciprocity of populations measured with a novel multi-dimensional method. Populations consistently showed an approximate 1:1 morph ratio with high sex organ reciprocity and high genetic diversity. We found high genetic differentiation of populations, showing a pattern of isolation by distance. The Rif mountains in NW Africa were the most important genetic barrier. The taxonomic treatment within the group was not related to the genetic differentiation of populations, but to their environmental differentiation. Genetic diversity was unrelated to latitude, elevation, population size, niche suitability or breeding system. However, there was a clear influence of ploidy level on the genetic diversity of populations, and a seeming centre–periphery pattern in its distribution. Our results suggest that polyploidization events, high outcrossing rates, isolation by distance and important geographical barriers to gene flow have played major roles in the microevolutionary history of this species complex.

Linum suffruticosum L. s.l. (Linaceae) is a taxonomic complex widespread in the western Mediterranean basin. It is characterized by its high cytogenetic diversity and its 3D heterostyly system, which makes it an obligate outcrosser. In this work we studied the patterns of genetic diversity and population structure throughout its distribution using neutral genetic data obtained from microsatellite markers. It is shown that there is no relationship between taxonomic treatment and genetic variability, so a revision of the taxonomy would be useful. L. suffruticosum s.l. has a high level of genetic diversity, promoted by polyploidization processes, and maintained by the existence of abundant and reproductively connected populations. The populations are genetically structured following a pattern of isolation by distance, with the Rif mountains as the most important genetic barrier. However, genetic diversity does not covary at the latitudinal or altitudinal level, nor is it related to population size or the proportion of stylar morphs. This suggests that variations in genetic diversity are not mostly determined by selective forces, but by stochastic processes., Linum suffruticosum L. s.l. (Linaceae) es un complejo taxonómico ampliamente extendido en la cuenca mediterránea occidental. Se caracteriza por su alta diversidad citogenética y su sistema de heterostília en 3D, lo que lo convierte en un outcrosser obligado. En este trabajo se estudian los patrones de diversidad genética y estructura poblacional a lo largo de su distribución utilizando datos genéticos neutros obtenidos a partir de marcadores de microsatélites. Se ha demostrado que no existe relación entre el tratamiento taxonómico y la variabilidad genética, por lo que sería útil una revisión de la taxonomía. L. suffruticosum s.l. presenta una elevada diversidad genética, promovida por procesos de poliploidización, y mantenida por la existencia de poblaciones abundantes y conectadas reproductivamente. Las poblaciones están estructuradas genéticamente siguiendo un patrón de aislamiento por distancia, con las montañas del Rif como la barrera genética más importante. Sin embargo, la diversidad genética no covaría con la latitud o la altitud, ni está relacionada con el tamaño de la población o la proporción de morfos estilares. Esto sugiere que las variaciones en la diversidad genética no están determinadas principalmente por fuerzas selectivas, sino por procesos estocásticos.