Study of flow and contemporary pollen dispersal, mating system, spatial distribution of genotypes and inbreeding depression in fragmented population Cariniana estrellensis (Raddi) Kuntze, using microsatellite loci
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2017-02-03
Autores
Kubota, Thaisa Yuriko Kuboyama [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularmente conhecida como jequitibá-branco, é uma espécie arbórea tropical típica de estágios sucessionais avançados, característica de florestas clímax. Apesar da sua importância ecológica, a espécie encontra-se ameaçada de extinção, principalmente devido à intensa exploração e degradação de seu ambiente natural. O objetivo deste trabalho foi investigar a diversidade genética, a estrutura genética espacial intrapopulacional (EGE), o sistema de cruzamento e o fluxo gênico contemporâneo de uma população de C. estrellensis, localizada em um fragmento florestal (448,2 ha) na cidade de Bataguassu (Estado do Mato Grosso do Sul, Brasil), utilizando marcadores microssatélites. Foram mapeadas, medidas (altura e diâmetro a altura do peito) e genotipadas todas as 285 árvores adultas encontradas na área e coletadas sementes de 20 árvores matrizes, 32 sementes por árvore para as análises de forma hierárquica dentro e entre frutos. Utilizando os genótipos de adultos e progênies foram investigadas a herança Mendeliana, ligação genética e o desequilíbrio genotípico de nove locos de C. estrellensis, os quais exibiram herança Mendeliana, não estão ligados e segregam de forma independente. Embora a riqueza alélica ( ), heterozigozidade observada ( ) e esperada ( ) foram similares entre adultos ( = 8,3, = 0,648, = 0,686) e sementes ( = 7,8, = 0,640, = 0,682), estes índices foram significativamente menores nas sementes. O índice fixação médio ( ) não foi significativamente maior do que zero, sugerindo ausência de endogamia nos adultos e nas sementes. A taxa de cruzamento multilocos ( ) foi significativamente menor que a unidade (1,0), sugerindo autofecundações. A taxa de cruzamento entre indivíduos parentes ( ) foi significativamente maior do que zero (0,062) e a correlação de paternidade foi maior dentro ( = 0,835) do que entre frutos ( = 0,062). O coeficiente médio de coancestria ( ) foi maior e o tamanho efetivo ( ) foi menor do que o esperado para progênies de populações panmíticas. O número estimado de árvores matrizes para a coleta de sementes para obter um tamanho efetivo de 150 foi de 52. A taxa de imigração de pólen foi de 9,4%. O raio efetivo de dispersão de pólen ( ) foi de 974 m. A análise de modelagem de dispersão de pólen de Kernel indicou o modelo de dispersão exponencial como o que melhor explica a dispersão de pólen, com média de dispersão de pólen de 610,9 m. Portanto, a população de C. estrellensis não está reprodutivamente isolada devido à dispersão de pólen a longas distâncias e apresenta grande potencial para fins de conservação genética in situ e ex situ.
Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularly known as jequitibá-branco, is a tropical tree species typical of advanced successional stages, characteristic of climax forests. Although it ecological importance, the species is threatened with extinction, mainly due to the intense exploitation and degradation of its natural environment. The objective of this study was to investigate the genetic diversity, intrapopulation spatial genetic structure (SGS), the mating system and contemporary gene flow of a population of C. estrellensis, located in a forest fragment (448.2 ha) in the city of Bataguassu (State of Mato Grosso do Sul, Brazil), using microsatellite markers. Were mapped, measured (height and diameter at breast height) and genotyped all 285 adult trees found in the area and collected seeds from 20 matrices trees, 32 seeds per tree for the hierarchical analyses within and among fruits. Using the genotypes of adults and progenies were investigated Mendelian inheritance, genetic linkage and genotypic disequilibrium of nine loci of C. estrellensis, which exhibited Mendelian inheritance, are not linkaged and segregate independently. Although the allelic richness ( R ), observed heterozygosity ( Ho ) and expected ( He ) were similar among adults ( R = 8.3, Ho = 0.648, He = 0.686) and seeds ( R = 7.8, Ho = 0.640, He = 0.682), these indexes were significantly lower in the seeds. The average fixation index ( F ) was not significantly greater than zero, suggesting absence of inbreeding in adults and seeds. The rate of multilocus outcrossing ( m t ) was significantly less than unit (1.0), suggesting selfing. The outcrossing rate between related individuals ( m s t t ) was significantly greater than zero (0.062) and the paternity correlation was higher within ( p(w) r = 0.835) than that among fruits ( p(a) r = 0,062). The average coefficient of coancestry ( ) was higher and the effective size ( Ne ) lower than expected for progenies of panmitic populations. The estimated number of matrices trees to collect seeds to obtain the effective size of 150 was of 52. The immigration rate of pollen was 9.4%. The effective radius of pollen dispersal ( ep r ) was of 974 m. The analysis of Kernel pollen dispersion modeling indicated the exponential dispersion model as the best explanation for pollen dispersion, with a pollen dispersion average of 610.9 m. Therefore, the population of C. estrellensis is not reproductively isolated due to the dispersion of pollen over long distances and presents great potential for in situ and ex situ genetic conservation purposes.
Cariniana estrellensis (Raddi) Kuntze (Lecythidaceae), popularly known as jequitibá-branco, is a tropical tree species typical of advanced successional stages, characteristic of climax forests. Although it ecological importance, the species is threatened with extinction, mainly due to the intense exploitation and degradation of its natural environment. The objective of this study was to investigate the genetic diversity, intrapopulation spatial genetic structure (SGS), the mating system and contemporary gene flow of a population of C. estrellensis, located in a forest fragment (448.2 ha) in the city of Bataguassu (State of Mato Grosso do Sul, Brazil), using microsatellite markers. Were mapped, measured (height and diameter at breast height) and genotyped all 285 adult trees found in the area and collected seeds from 20 matrices trees, 32 seeds per tree for the hierarchical analyses within and among fruits. Using the genotypes of adults and progenies were investigated Mendelian inheritance, genetic linkage and genotypic disequilibrium of nine loci of C. estrellensis, which exhibited Mendelian inheritance, are not linkaged and segregate independently. Although the allelic richness ( R ), observed heterozygosity ( Ho ) and expected ( He ) were similar among adults ( R = 8.3, Ho = 0.648, He = 0.686) and seeds ( R = 7.8, Ho = 0.640, He = 0.682), these indexes were significantly lower in the seeds. The average fixation index ( F ) was not significantly greater than zero, suggesting absence of inbreeding in adults and seeds. The rate of multilocus outcrossing ( m t ) was significantly less than unit (1.0), suggesting selfing. The outcrossing rate between related individuals ( m s t t ) was significantly greater than zero (0.062) and the paternity correlation was higher within ( p(w) r = 0.835) than that among fruits ( p(a) r = 0,062). The average coefficient of coancestry ( ) was higher and the effective size ( Ne ) lower than expected for progenies of panmitic populations. The estimated number of matrices trees to collect seeds to obtain the effective size of 150 was of 52. The immigration rate of pollen was 9.4%. The effective radius of pollen dispersal ( ep r ) was of 974 m. The analysis of Kernel pollen dispersion modeling indicated the exponential dispersion model as the best explanation for pollen dispersion, with a pollen dispersion average of 610.9 m. Therefore, the population of C. estrellensis is not reproductively isolated due to the dispersion of pollen over long distances and presents great potential for in situ and ex situ genetic conservation purposes.
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Conservação genética, Espécie arbórea tropical, Fluxo gênico, Marcadores microssatélites