Estrutura genética e sistema de cruzamento em Eugenia dysenterica DC. (Mvrtaceae)
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2014-03-28
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Universidade Federal de Goiás
Resumo
The genetic structure of a species corresponds to the amount of genetic
variability and its distribution within and among local populations and individuals. The
patterns of variability among individuals in a local population are highly dependent of
mating system. The goal of this study was to evaluate the mating system, the diversity
and genetic structure in populations of E. dysenterica in local and regional scale. The
assessment of the mating system and the analysis of genetic structure at the local scale
were performed in a population of Mimoso – GO and for the analysis of genetic
structure at the regional scale were analyzed 23 natural populations of E. dysenterica
derived from six Brazilian states (Goiás, Minas Gerais, Bahia, Mato Grosso, Tocantins
and Piauí). For all studies seven polymorphic microsatellite loci were used. Considering
the 20 families analyzed, the multilocus outcrossing rates (tm = 0.918) and single locus
(ts = 0.797) were high and significant. From a total of 399 seeds evaluated, it was
possible to determine the pollen donor to 218 seeds (55%) with confidence level of
90%, 174 seeds (44%) with confidence level of 95% and 65 seeds (16%) with
confidence level of 99%. In 15 families evaluated were possible to verify the occurrence
of multiple paternity, with the number of pollen donor per fruit ranged from one to
three. The results presented show that the species E. dysenterica presents mixed mating
system and that there is multiple paternity in this species. The intrapopulational spatial
genetic structure was positive (R2 = 0.01646, p < 0.001), which was expected since
species generally have spatial restriction to disperse. The spatial genetic structure was
significant (Sp = 0.0143) and genetic neighborhood (Nb) was equal to 69.93 km. On
average, about 30 individuals were analyzed by subpopulation for all loci. The average
number of alleles per locus was equal to 9, the genetic diversity was high (0.725) and
the observed frequency of heterozygotes (Ho) was 0.610. Were found 18 private alleles
in 10 subpopulations. The results for the fixation index ((f) in the subpopulations ranged
between -0.058 and 0.338, with an overall value of 0.162, indicating excess of
homozygotes in relation to the expected under HWE. The genetic differentiation
between subpopulations can be considered relatively high (FST = 0.161). The Mantel test
indicates that the genetic divergence of 24 subpopulations evaluated is structured in
geographic space (r = 0.427, p < 0.001), suggesting that the model of isolation by
distance or stepping-stone are adequate to explain the spatial pattern of genetic
divergence among subpopulations of E. dysenterica evaluated.
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BARBOSA, Ana Clara de Oliveira Ferraz. Estrutura genética e sistema de cruzamento em Eugenia dysenterica DC. (Mvrtaceae). 2014. 126 f. Tese (Doutorado em Genética e Melhoramento de Plantas) - Universidade Federal de Goiás, Goiânia, 2014.