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Universidad Nacional Mayor de San Marcos (2014)

Diversidad genética y relaciones filogenéticas de Orthopterygium huaucui (A. Gray) Hemsley, una anacardiaceae endémica de la vertiente occidental de la Cordillera de los Andes

Jiménez Vásquez, Víctor Alberto

Titre : Diversidad genética y relaciones filogenéticas de Orthopterygium huaucui (A. Gray) Hemsley, una anacardiaceae endémica de la vertiente occidental de la Cordillera de los Andes

Auteur : Jiménez Vásquez, Víctor Alberto

Université de soutenance : Universidad Nacional Mayor de San Marcos

Grade : Título profesional de Biólogo con mención en Botánica 2014

Résumé
Peruvian western slopes of the Andes are an arid ecosystem rich in endemic flora currently threatened by industrial and urban expansion. It is characterized by a flora of cacti and deciduous shrubs. Orthopterygium huaucui (A. Gray) Hemsley is an endemic monotypic genus of Anacardiaceae family which inhabits this ecosystem as scattered thickets on rocky slopes along 500 km of the central coast and whose closest species belonging to the genus Amphipterygium (found in Mexico and Central America). Between those two genera there is a disjunction of more than 3500 km. In order to determine 1) the population structure of O. huaucui, 2) the phylogenetic position of O. huaucui within the tribe Rhoeae of the Anacardiaceae family and 3) the divergence time of O. huaucui within Anacardiaceae, we performed a Bayesian phylochronology calibrated with five fossil records and determined the genetic diversity. To get these aims we sequenced TrnL, Rps16 (plastid introns) and ITS (nuclear) markers broadly used in plant phylogenetic and phylogeographic studies. We extracted DNA from 51 individuals of O. huaucui, we amplified the three regions by PCR, we sequenced each one and edited manually. We downloaded sequences of other anacardiacean species available in GenBank. The disjunction between Orthopterygium and Amphipterygium resulted in 16,52 and 14,82 million years and a genetic distance between these two species was similar to lineages with greater diversification ; whereas no intraspecific mutations were detected in Orthopterygium. This result would respond to a low dispersion or low mutation rate in view of ecological and molecular studies. In spite of the fact that the absence of mutations in nuclear markers is a common pattern in recent species and the Miocenic origin of Orthopterygium, we propose that this species was affected by a severe genetic bottleneck. Moreover, by considering as the single representative of the genus, Orthopterygium huaucui would be the result of an ancestral species migration from the northern hemisphere which has got the western slopes, an arid ecosystem for more than 15 million years, through a well-established Panama isthmus.

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Page publiée le 22 janvier 2019