Browsing by Author "Eaton, Lafayette"

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    Heterogeneous genetic structure in a natural population of Rauli (Nothofagus nervosa)
    (2011) Carrasco, Basilio; Eaton, Lafayette; Letelier, Luis; Diaz, Carole; Garcia-Gonzales, Rolando
    B. Carrasco, L. Eaton, L. Letelier, C. Diaz, and R. Garcia-Gonzales. 2011. Heterogeneous genetic structure in a natural population of Rauli (Nothofagus nervosa). Cien. Inv. Agr. 38(3): 441-452. Heterozygote deficiencies in natural populations of outbreeding tree species are common and thought to be due mainly to biparental inbreeding. Inbreeding is believed to be caused by family structure within populations, a product of limited seed dispersal and probably limited pollen dispersal. Although both theory and simulation studies predict that structure should be apparent where trees are isolated by distance, most studies of structure in natural populations have detected only a weak spatial genetic structuring. In this contribution, we compare the use of spatial autocorrelation methodology and F statistics with the concept of relatedness to examine the spatial genetic structure in the natural population of a native southern beech and to explore the discrepancy between theory and observations. Autocorrelation detected structure in only a few of the nine enzyme loci tested in an estimated patch size of approximately 10 m. By successively eliminating the largest distances in the Gabriel map, the population was separated into groups or patches of neighbors, which were then tested for relatedness. Three groups of relatives were found interspersed with seven groups of unrelated individuals. The F statistics for these groups also showed weak genetic structure. We suggest that heterogeneity of family structure within natural populations may be one reason why more spatial genetic structure has not been detected.
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    Heterogeneous genetic structure in a natural population of raulí (Nothofagus nervosa).
    (2011) Carrasco Gálvez, Basilio Alejandro; Eaton, Lafayette; Letelier, Luis; Díaz Gálvez, Carole; García-Gonzáles, Rolando
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    Proximal causes of genetic variation between and within populations of rauli (Nothofagus nervosa)
    (PONTIFICIA UNIV CATOLICA CHILE, FAC AGRONOMIA INGENIERIA FORESTAL, 2009) Carrasco, Basillo; Garnier, Maurice; Eaton, Lafayette; Guevara, Rafael; Caru, Margarita
    B. Carrasco. M. Garnier. L. Eaton. R. Guevara, and M. Caru. 2009. Proximal causes of genetic variation between and within populations of rauli (Nothofagus nervosa). Cien. Inv. Agr. 36(2):229-238. Random Amplified Polymorphic DNA(RAPD) markers were used to assess the genetic diversity of 587 individuals, belonging to 22 populations of Nothofagus nervosa that were distributed through the Coastal (38 degrees S to 41 degrees S) and Andes Mountains ill Central-Southern Chile (36 degrees S to 40 degrees S). The objective of this Study Was 10 complement the genetic inferences previously determined by isozyme analysis, in order to obtain more accurate genetic diversity estimations. We scored 81.8% of the polymorphic loci of the samples tested. The average incidence of genetic polymorphism Within populations was high, With Values ranging between 33% and 63%,. Analysis of molecular variance (AMOVA) showed most of the genetic variation was distributed within populations (87.6%). but F-ST values (F-ST = 0.124: p < 0.00001) indicated that there was also a significant difference among populations. A discriminant analysis revealed three geographically defined groups and showed that 14 loci explained 87.2% of the genetic differentiation among N. nervosa populations. Watterson's neutrality test and Ohta's two-locus analysis of linkage disequilibrium (LD) both suggested that stochastic demographic and environmental factors can partially explain the loci variation observed in the RAPDs. The role of the last glaciations, as well as some conservation and breeding strategies, may have influenced Current genetic variation and fragmentation in this species.
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    Proximal causes of genetic variation between and within populations of raulí (Nothogafus nervosa).
    (2009) Carrasco, Basilio; Garnier, Maurice; Eaton, Lafayette; Guevara, Rafael; Carú, Margarita