Consequences of habitat fragmentation on genetic structure of Chamaedorea alternans (Arecaceae) palm populations in the tropical rain forests of Los Tuxtlas, Veracruz, Mexico

Juan Manuel Peñaloza-Ramírez, Bernardo Aguilar-Amezquita, Juan Núñez-Farfán, Nidia Pérez-Nasser, Ana Luisa Albarrán-Lara, Ken Oyama

Resumen


Chamaedorea alternans is a palm species that has suffered from selective extraction, and habitat loss. We collected 11 populations from fragmented and conserved forest. We assess genetic variation of C. alternans, genetic exchange, differentiation, bottlenecks, effective population size and signals of natural selection. Genetic diversity was higher in conserved than in fragmented forest but not significant. Fragmentation did not play a significant role in genetic diversity, possibly due to the populations heterogeneity. C. alternans has been subject to a pronounced isolation of trees as a product of logging, thus raising inbreeding. Bayesian clustering show a trend towards an increased structuring over the course of generations but also, indicates that populations have recently gone through a bottleneck. The bottleneck following deforestation was not severe enough to lower the effective size, this could lead to high standing genetic diversity, providing a buffer against genetic erosion. We observed directional and balancing selection in C. alternans. Maintenance of variability and increased differentiation signify that their populations have been subject to a differential selective pressure at the ecological and the landscape level, combined effect could lead to disturb pollination and dispersion processes, modifying in the long term the effective population size.


Palabras clave


Tropical forest; Genetic diversity; Genetic bottlenecks; Bayesian cluster analysis; Test of natural selection

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Chamaedorea alternans, is a palm species that has suffered from selective extraction and possibly the genetic consequences. Samples were collected from 11 populations in Los Tuxtlas Veracruz, used for electrophoretic analysis encoded by fourteen loci. Genetic diversity was higher in conserved (Na = 3.62, HO = 0.443) than fragmented forest (Na = 3.60, HO = 0.42) but not significant. Results suggest that fragmentation did not play a substantial role in genetic diversity in isolated habitats and possibly due to populations with different evolutionary histories. C. alternans have been subject to a pronounced isolation of mature trees in fragmented zones that reduces the density of adult trees, thus raising inbreeding. Bayesian clustering indicates a trend towards an increased structuring over the course of generations. We observed a continuous natural gene flow among geographically close populations, which may be responsible for the low-moderate differentiation across landscapes. We observed selection in populations from C. alternans particularly directional and balancing selection. Decrease and maintenance of genetic variability and increased differentiation, signify that their populations have been subject to a historical differential selective pressure at the ecological and the landscape level, combined effect could lead to disturb pollination, dispersion processes, modifying the effective population size.




DOI: http://dx.doi.org/10.1016/j.rmb.2016.07.004

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Revista Mexicana de Biodiversidad, Año 3, No. 12, enero-marzo 2014, es una publicación trimestral editada por la Universidad Nacional Autónoma de México, Ciudad Universitaria, Delegación Coyoacán, C.P. 04510, Ciudad de México, a través del Instituto de Biología, Tercer Circuito Universitario s/n, Ciudad Universitaria, Col. Copilco, Del. Coyoacán, C.P. 04510, Ciudad de México, Tel. (55)56229164, http://www.revista.ib.unam.mx/index.php/bio/, falvarez@ib.unam.mx.Editor responsable: Dr. Fernando Álvarez Noguera. Reserva de Derechos al uso Exclusivo No. 04-2013-092709142100-203, ISSN: 2007-8706, ambos otorgados por el Instituto Nacional del Derecho de Autor, Responsable de la última actualización de este número, Instituto de Biología, UNAM, Dr. Fernando Álvarez Noguera, Tercer Circuito Universitario s/n, Ciudad Universitaria, Col. Copilco, Del. Coyoacán, C.P. 04510, Ciudad de México, fecha de la última modificación: 25 de agosto de 2016.

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