Molecular Ecology and Evolution
Ramírez-Padilla, Cynthia A. , Valverde, Teresa , Mandujano, Maria .
Using microsatellites to assess seed dispersal in a metapopulation of the epiphyte Tillandsia recurvata (Bromeliaceae) in a Mexican semidesert.
Seed dispersal is an important process determining metapopulation dynamics, since it allows the colonization of available habitat patches. Although seed dispersal is an elusive process, the recent development of molecular markers has opened the opportunity to trace dispersal routes and evaluate its magnitude. In this study we used three microsatellite loci to evaluate the dispersal between local populations within a metapopulation of Tillandsia recurvata in the semiarid region of TehuacÃ¡n, Mexico. This species is an epiphyte which forms local populations on colonized trees; it is self-fertilized and its seeds are wind dispersed. We selected nine local populations and collected tissue samples from all the adults and seedlings per population. These populations differed in their isolation level, evaluated as the mean distance from the focal tree to the closest colonized trees (which varied from 1 to 42 m). We described the main population genetics variables and carried out a paternity analysis (by exclusion) to evaluate the proportion of seedlings originating from parents outside the population (i.e. immigration rate). The results indicated that Ho varied from 0.60 to 0.74, and He from 0.62 to 0.79. There was an excess of heterocigotes among adults (F = -0.08 to -0.12), but a deficit among seedlings (F = 0.14 to 0.21). Thus, selection may be favoring heterocigotes during early life-cycle stages. Genetic differentiation between population was low (Fst = 0.094), apparently due to high gene flow. The relationship between Fst and the geographic distance between populations (0.12 to 18 km) was not significant. The paternity analysis revealed that a high proportion (57 to 100%) of the seedlings established within a population do not descend from local parents. The proportion of immigrants was not correlated with the isolation level. We discuss these results in the context of the genetics and dynamics of the metapopulation.
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1 - Universidad Nacional Autónoma de México, Facultad de Ciencias, Depto. de Ecología y Recursos Naturales, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, Mexico City, D.F., 04510, México
2 - Universidad Nacional Autónoma de México, Facultad de Ciencias, Detpo. de Ecología y Recursos Naturales, Facultad de Ciencias, Circuito Exterior, Ciudad Universitaria, Mexico City, D.F., 04510, Mexico
3 - Universidad Nacional Autonoma de Mexico, Instituto de Ecologia, Ciudad Universitaria, A.P. 70-275, Mexico, D.F., 04510, Mexico
isolation by distance
Presentation Type: Poster:Posters for Topics
Location: Ball Room & Party Room/SUB
Date: Monday, July 28th, 2008
Time: 12:30 PM