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22 mayo 2009

Juan C Villareal obtiene financiamiento de la NSF para su tesis doctoral

Felicidades a Juan Carlos, estudiante panameño, actualmente en la Universidad de Connecticut (Ecology and Evolutionary Biology) por su reciente adjudicación de financiamiento de la NSF!

Juan Carlos ha tratado de enfocar su investigación en aspectos biológicos mas amplios, pero aun interesado en la parte sistemática de los antoceros, lo que en parte constituye el primer capitulo de su tesis doctoral.

El dinero de la NSF es para hacer dos viajes de campo a la region de los Apalaches del Sur y Costa Rica para colectar poblaciones de Megaceros (pronto Nothoceros) aenigmaticus y comparar poblaciones sexuales y asexuales. Ademas el dinero será para financiar el trabajo de genetica de poblaciones utilizando microsatelites. Aqui el resumen oficial del proyecto, el cual explica un poco el alcance del proyecto.

The proposed research focuses on the evolutionary history of the asexual hornwort M. aenigmaticus and the consequences of the loss of sexuality on the genetic diversity and structure in the Southern Appalachian (SA) populations. The first part of this study used a multilocus approach to untangle the phylogenetic relationships within the Nothoceros alliance and test the monophyly of M. aenigmaticus. In addition, estimates of the approximate time of origin and the maximum age for the loss of sexuality from a sexually reproducing ancestor within a biogeographical context have been inferred. Data from five loci reveal that the Southern Appalachian SA populations compose a monophyletic lineage that is nested among Neotropical Páramo populations that are also dioicous but sexually reproducing. The clade of SA M. aenigmaticus is estimated to have originated in the Plio-Pleistocene, which is also the maximum age for the loss of sexual reproduction. Haplotype variation based on these four loci is limited, but suggest a differentiation among populations and in particular among males and females.
To assess the genotypic diversity within the asexual SA populations and compare it to levels within the sexual Páramo populations a microsatellite library has been developed in 2008. Preliminary screening of one locus shows allelic polymorphism among 16 SA populations. The proposed research for the year 2009-2010 focuses on a complete survey of at least 8 microsatellite loci for around 400 individuals from populations from the SA region and at least 100 individuals from tropical alpine localities in Costa Rica. Predictions based on population genetic theory suggest that SA populations should have a smaller effective population size, lower allelic diversity and high levels of linkage disequilibrium compared to the Páramo. Funds requested from NSF will be used to continue pursue fragment analysis and further increase population sampling size in the SA region and Costa Rica.
A last component of the research will be focusing on the molecular signature of the transition to asexuality using nuclear coding regions. Megaceros aenigmaticus, as other bryophytes, have a gametophyte (haploid) dominant with alleles directly exposed to selective pressures. A test of neutrality, recombination and demographic analyses will be conducted. The expectation is that SA populations may have an increase of amino acid changes suggesting little purifying selection, no recombination and reduction in effective population size through time.
Intellectual merit: This project will thus contribute to our understanding of fundamental population genetic aspects in bryophytes, and thereby provide a contrast to hypotheses derived from clonal vascular plants and other asexual systems. A fingerprinting characterization of conspecific allopatric asexual and sexually reproducing populations will allow assessing the genetic consequences and the molecular signatures associated with the loss of sex. Results of this research will provide a scientific basis for the conservation status of the only North American species of the genus.
Broader impact: This research offers training and educational opportunities at the local, national and international scale. At local scale, I will be complementing my background in plant ultrastructure and development with a comprehensive analysis of molecular markers. Additionally, I will engage one undergraduate student, already currently trained in basic molecular techniques working in the lab, in conducting scientific research and train her on fingerprinting techniques. At the national scale, a distribution map of M. aenigmaticus is being developed and will be distributed as a laminate sheet with additional information on the biology of the species to all US National Parks where Megaceros aenigmaticus occurs. A talk will be held at the Great Smoky Mountain National Park Center during the summer of the year 2010 to provide a detailed account of M. aenigmaticus as the research unfolds. Information with details on the results of the research will be available through my website at UCONN . At the international scale, insights into the genetic structure and evolutionary significance of Páramo populations from Costa Rica will be shared through a talk at the Instituto Nacional de la Biodiversidad (INBio), in June 2009. These activities aim at increasing awareness of this species with such restricted and vanishing habitat in the Neotropics prone to human over-exploitation and global warming effects.

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