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| Author(s): |
Maria Carolina Silva
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | Piracicaba. |
| Institution: | Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC) |
| Defense date: | 2011-02-14 |
| Examining board members: |
Paulo Yoshio Kageyama;
Giselda Durigan;
Mario Luiz Teixeira de Moraes;
Vera Nisaka Solferini;
Roberto Tarazi
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| Advisor: | Paulo Yoshio Kageyama |
| Abstract | |
The Cerrado biome is considered a critical area for worldwide conservation due to its endemism and the current devastation speed. The fragmented and disturbed natural landscapes are the biggest challenges for the maintenance of genetic variability, which today has a leading role in defining conservation and management strategies of natural populations. This work intends to propose recommendations for in situ conservation strategies based on genetic markers. With the help of eight nuclear microsatellite loci, the study will verify the genetic diversity, the breeding system, the spatial genetic structure and the gene flow of Tabebuia aurea (Bignoniaceae) in Cerrado remnants of the State of São Paulo and Mato Grosso do Sul. Eight populations of T. aurea with 290 adult trees were mapped. In addition, 750 progeny were produced (25 seedlings of 30 mother-trees), totaling 1040 genotyping. The results indicated that adult trees occasionally have higher heterozygosity than seedlings and the fixation index in the populations were high and significant. The loci analyzed indicated that most populations of T. aurea had structuring of the genetic variability. There are similarities between regions and populations, but there is no clear pattern of spatial genetic structure, although the correlogram supported the hypothesis of spatially restricted seed dispersal. In turn, high immigration rates of pollen were found on populations of Assis (74%) and Pedregulho (87%) and the distances of the pollen contemporary distribution had been variating between 0 and 167m to Assis and between 0 and 7002m to Pedregulho, what suggests an intense movement of genes in the populations. According to the outcrossing rates estimated, the populations showed an outcrossing breeding system in Assis and Pedregulho ( = 0.997, = 1.000, respectively), indicating the presence of self-incompatibility mechanisms in this species. It was found that the population genetic divergence was not equally distributed among the population, and so, isolation by distance phenomena may be occuring. The minimum viable area for conservation estimates of adults trees indicated that most part of the areas have sizes below of recommended. Only the State Park Furnas do Bom Jesus, Pedregulho, SP, contains sufficient area for the conservation of evolutionary potential of populations of T. aurea. The results suggest that the seed collected for conservation strategies, must come from a minimum of 18 and 20 mother-trees, respectively, from Assis and Pedregulho. (AU) | |