Variabilidade e estrutura genética populacional nas espécies Manihot irwinii D.J. Rogers & Appan e Manihot violacea Pohl (Euphorbiaceae Juss.)
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2016-05-05
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Universidade Federal de Goiás
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The Euphorbiaceae family is one of the largest and most diverse of the Angiosperms,
predominating trees and shrubs and is present in most of the world. The genus Manihot
belongs to the family Euphorbiaceae and its origin is recent probably dates from the Miocene
and possible in the south of Mexico. It is a group that presents a numerically stable set of
chromosomes (2n=36). M. irwinii is an endemic species from the state of Goiás with a
disjunct and restricted distribution to the rupestrian cerrado and M. violacea can be found in
the states of Goiás, Minas Gerais, Distrito Federal and Mato Grosso occurring in cerrado rock
and in other types of formations. Most studies of genetic diversity in the genus are with the
species Manihot esculenta (cassava). That is why it is important to study the distribution of
genetic variability in populations of two species Manihot irwinii and Manihot violacea.
Leaves of individuals from three localities of the species M. irwinii and three others of M.
violacea were sampled. To obtain the genotypes, seven microsatellite markers developed for
Manihot esculenta and transferred to M. irwinii and M. violacea were used. The six
populations were genotyped in an automatic DNA analyzer in two multiplex systems. The M.
irwinii species presented a mean of 5,5 alleles per locus and a moderate diversity (He=0,446)
and the values of θ=0.241 and F=0.207 indicated a high genetic structure among the
populations. It was detected for M. violacea a mean of 8,5 alleles per locus and a moderate
diversity (He=0,478) and high divergence among populations of M. violacea (θ=0.420 and
F=0.441). For both species the result of the Structure program contributes with this result
showing that there is little mixture between the populations that can be result of restricted
genetic flow and possible action of the genetic drift, since the global f values were not
significant indicating that the system of Is not responsible for the high structuring of
populations. The two species that occur in the Serra dos Pireneus State Park share 23 alleles
(M. irwinii: 76% and M. violacea: 79%), with five alleles being exclusive to the Park. The
divergence between the two was high (θ=0.298) and lower than that found among populations
of M. violacea. It is possible that the high percentage of shared alleles is trace of a historical
flow and that at present there is a barrier between species.
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OLIVEIRA-ORDIALE, P. R. Variabilidade e estrutura genética populacional nas espécies Manihot irwinii D.J. Rogers & Appan e Manihot violacea Pohl (Euphorbiaceae Juss.). 2016. 80 f. Dissertação (Mestrado em Genética e Biologia Molecular) - Universidade Federal de Goiás, Goiânia, 2016.