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Diversidade gen?tica em popula??es naturais de Hancornia speciosa Gomes no Estado do Rio Grande do Norte: implica??es para conserva??o

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Previous issue date: 2014-12-15 / A esp?cie Hancornia speciosa Gomes ? nativa do Brasil com ampla distribui??o no territ?rio nacional. Seu fruto ? bastante apreciado pelas popula??es locais, sendo utilizado para fabrica??o de doces, sorvetes e polpas. O crescimento urbano e a expans?o agr?cola favoreceram ? fragmenta??o das ?reas florestais onde a esp?cie ocorre, com a consequente redu??o do tamanho populacional, podendo ocasionar s?rias implica??es para a manuten??o da esp?cie a longo prazo. O objetivo deste estudo foi avaliar a diversidade gen?tica remanescente em sete popula??es de H. speciosa do estado do Rio Grande do Norte, ap?s selecionar marcadores de DNA entre repeti??es de sequ?ncias simples do genoma (ISSR). Na avalia??o da qualidade do DNA, o material gen?tico obtido a partir do caule apresentou pureza semelhante ao extra?do da folha, obtendo valores para a raz?o entre as absorv?ncias (A260/A280) de 1,46 para o caule e de 1,42 para a folha, ficando, ambos, um pouco abaixo do valor considerado ?timo que ? entre 1,5 e 2,5. O tecido caulinar apresentou DNA de qualidade para an?lises moleculares da esp?cie. Foram testados 19 primers ISSR onde seis foram selecionados (UBC 808, UBC 810, UBC 826, UBC 827, UBC 841, UBC 842) por apresentarem locos n?tidos, inequ?vocos e em maior n?mero, totalizando 63 locos, sendo que 30 (47,62%) apresentaram polimorfismo. O valor de PIC (conte?do de informa??es polim?rficas) para os primers selecionados atingiu a m?dia de 0,37, variando de 0,26 a 0,44, indicando que s?o ?teis para avaliar a diversidade gen?tica da esp?cie. Para o total das popula??es, o n?mero de locos polim?rficos foi de 57 (81,43%), com o n?mero total de alelos efetivos (Ne) 1,493. A diversidade gen?tica de Nei (He) foi de 0,287 e o ?ndice de Shannon (I) o valor de 0,429. Entre as popula??es o n?mero de locos polim?rficos foi considerado baixo, variando de 29 (41,43%) na popula??o Cotovelo, ? 33 (47,14%) em Maca?ba. Os ?ndices de diversidade He e I para cada popula??o variou respectivamente de 0,161 e 0,237 na popula??o Parque das Dunas ? 0,206 e 0,294 na popula??o Maca?ba. De acordo com a an?lise bayesiana os gen?tipos foram divididos em cinco grupos distintos (K = 5). Os padr?es observados para diversidade al?lica indicam a ocorr?ncia de gargalo gen?tico em todas as popula??es, de acordo com o modelo de passos de muta??o. O modelo de alelos infinitos revelou desequil?brio entre muta??o e deriva gen?tica apenas na popula??o Parque das Dunas. Os ?ndices de fluxo g?nico (Nm) revelaram troca de alelos entre todas as popula??es. Os resultados obtidos sugerem que a diversidade gen?tica est? distribu?da em diversas popula??es, sendo essencial a conserva??o das ?reas de sua ocorr?ncia para a manuten??o da diversidade gen?tica da esp?cie. / The Hancornia speciosa Gomes is a native of Brazil with wide distribution in the country. Its fruit is well appreciated by local people and is used for the manufacture of sweets, ice creams and pulps. Urban growth and agricultural expansion led to fragmentation forest areas where the species occurs, with a consequent reduction in population size, which can cause serious implications for the maintenance of long-term species. The objective of this study was to evaluate the remaining genetic diversity in seven populations of H. speciosa at Rio Grande do Norte state. In DNA's quality evaluation, the genetic material obtained from stems showed similar purity to the extracted sheet, obtaining values for the ratio between the absorbance (A260/A280) of 1.46 for the stem and 1.42 for the sheet, both were slightly below the value considered optimal which is between 1.5 and 2.5. The stem tissue showed DNA quality for molecular analyzes of the species. For the selection, 19 ISSR primers were tested, six of them were selected (UBC 808, UBC 810, UBC 826, UBC 827, UBC 841, UBC 842), for presenting clear locus, unambiguous and in great numbers, totaling 63 locus, and 30 (47.62%) showed polymorphism. The PIC value (polymorphic content information) for the selected primers averaged 0.37, ranging from 0.26 to 0.44, indicating that they are useful to evaluate the genetic diversity of the species. For the total population, the number of polymorphic locus was 57 (81.43%), with the total number of effective alleles (Ne) 1.493. The genetic diversity of Nei (He) was 0.287 and the Shannon index (I) was 0.429. Among populations the number of polymorphic locus was considered low, ranging from 29 (41.43%) in Cotovelo's population, to 33 (47.14%) in Maca?ba. The diversity indices He and I for each population ranged respectively 0.161 and 0.237 in Parque das Dunas's population to 0.206 and 0.294 in Maca?ba's population. According to the Bayesian analysis, the genotypes were divided into five groups (K = 5). The patterns observed in allelic diversity indicate the occurrence of bottleneck in all populations, according to the model of mutation steps. The infinite alleles model revealed imbalance between mutation and genetic drift only in the Parque das Dunas's population. The gene flow rates (Nm) revealed an exchange of alleles between all populations. The results suggest that genetic diversity is distributed among different populations, it is essential to conservation of areas of its occurrence to maintain the genetic diversity of the species.

Identiferoai:union.ndltd.org:IBICT/oai:repositorio.ufrn.br:123456789/22837
Date15 December 2014
CreatorsCosta, Daniel Ferreira da
Contributors01196769664, Fajardo, Cristiane Gouvea, 06639456664, Brand?o, Murilo Malveira, 06028849693, Vieira, F?bio de Almeida
PublisherPROGRAMA DE P?S-GRADUA??O EM CI?NCIAS FLORESTAIS, UFRN, Brasil
Source SetsIBICT Brazilian ETDs
LanguagePortuguese
Detected LanguagePortuguese
Typeinfo:eu-repo/semantics/publishedVersion, info:eu-repo/semantics/masterThesis
Sourcereponame:Repositório Institucional da UFRN, instname:Universidade Federal do Rio Grande do Norte, instacron:UFRN
Rightsinfo:eu-repo/semantics/openAccess

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