Eucalyptus cladocalyx F. Muell é distribuída em quatro regiões isoladas do sul da Austrália: Kangaroo Island, Flinders Ranges e em duas zonas da Eyre Peninsula. A espécie tem a capacidade de crescer em condições ambientais extremas como ambientes secos e solos salinos. O objetivo do presente estudo foi examinar a diversidade genética em 45 famílias de meio-irmãos cultivadas no norte do Chile, as quais são originarias de cinco localidades diferentes (procedências). A variabilidade genética foi avaliada usando marcadores moleculares ISSR (Inter Simple Sequence Repeat). Os resultados mostraram baixo nível de diversidade genética dentro de populações (He = 0,113 a 0,268) em contraste com outras espécies de Eucalyptus. Adicionalmente, houve uma significativa diferenciação genética entre procedências (Φst = 0.14), coincidindo com a reportada em estudos anteriores. Kangaroo Island é a procedência mais diferenciada. O presente estudo evidenciou que os recursos existentes no Chile são uma amostra representativa das populações Australianas e, portanto, o germoplasma cultivado no norte do Chile seria suficiente para os programas de melhoramento. A tecnologia de marcadores ISSR poderia ser uma alternativa para identificar genótipos de interesse no processo de seleção.

Eucalyptus cladocalyx F. Muell is a tree endemic to southern Australia and is distributed across four isolated regions: Kangaroo Island, southern Flinders Ranges, and two geographical zones in Eyre Peninsula. E. cladocalyx is capable of growing under extreme environmental conditions, including dry and saline soils. The objective of this study was to analyze genetic diversity in 45 half-sib families planted in northern Chile that are distributed across five different zones (provenances). Genetic variability was assessed using ISSR (Inter Simple Sequence Repeat) molecular markers. The results showed low levels of genetic diversity within populations (He = 0.113 to 0.268) in contrast with other Eucalyptus species. In addition, there was a significant genetic differentiation among provenances (Φst = 0.14); populations from the Kangaroo Island provenance showed more differentiation than any other population. These results are in agreement with previous studies of the species. Our study revealed that Chilean resources are a representative sample of Australian populations; therefore, the germplasm planted in northern Chile would be sufficient for the development of improvement programs. ISSR-Marker technology could be an alternative to identify genotypes of interest in material selection.

O objetivo deste trabalho foi determinar parâmetros genéticos para retidão do tronco em Eucalyptus cladocalyx, com o intuito de selecionar árvores retas, porém com o mínimo impacto sobre o crescimento. Os ensaios foram conduzidos em dois locais no semi-árido do Chile em delineamento de blocos ao acaso com 49 famílias de meios-irmãos. Os parâmetros foram estimados com modelo bicaráter de árvores individuais, usando inferência Bayesiana via algoritmo de Gibbs. A retidão do tronco mostrou ser moderadamente herdável com h²=0,40 [0,29-0,57]. Herdabilidades para diâmetro e altura foram de 0,30 [0,24-0,38] e 0,30 [0,22-0,44]. Correlações genéticas entre retidão e crescimento não diferem estatisticamente de zero. A interação genótipo-ambiente não foi significativa (p>0,05) para as características. O moderado grau de controle genético permitirá a obtenção de importantes ganhos genéticos em ambientes com déficit hídrico.

The aim of this study was to determine genetic parameters for straightness of the trunk of Eucalyptus cladocalyx, with a view to the selection of straight trees, while keeping the impact on growth minimal. The tests were conducted at two locations in the semi-arid region of Chile, using a randomized block design, with 30 replications and 49 half-sib families. The parameters were estimated by a bi-character model of individual trees, using Bayesian inference by Gibbs algorithm. The heritability for stem straightness was shown to be moderate, with h²=0.40 [0.29-0.57]. Heritabilities for diameter and height were moderate: 0.30 [0.24-0.38] and 0.30 [0.22-0.44]. Genetic correlations between straightness and growth were statistically not different from zero. The genotype-environment interaction was not significant (p>0.05) for the traits. The moderate degree of genetic control allows significant genetic gains in environments under water stress.

Acacia species have valuable agronomic characteristics, such as the tolerance to unfavorable environmental conditions. In this study, genetic parameters and selection response in Acacia saligna shrubs were investigated in two arid environments of northern Chile: Cuz-Cuz and El Tangue. The quantitative traits were assessed in 5 year-old shrubs. A Bayesian approach, implemented using Gibbs sampling algorithm, was used in the data analysis. The tree survival was 87.3% and 81.8% in Cuz-Cuz and El Tangue, respectively, confirming the potential of A. saligna in northern Chile. The estimates of posterior mode of the heritability ranged from h2=0.13 (survival) to h2=0.25 (shrub crown diameter). Estimated genetic gain (individual tree selection) ranged from 6 to 14% (selection intensity of 20%). Bayesian credible intervals (p=95%) for genotype-environment correlations included zero, indicating a significant interaction for survival, crown diameter and height. Shrub selection in multipurpose planting will depend on optimizing economical traits by selecting genotypes that perform well on a particular environment.

Las especies de acacia poseen características valiosas, como la tolerancia a condiciones ambientales desfavorables. En el presente estudio, se investigaron parámetros genéticos y la respuesta a selección en arbustos de Acacia saligna, en dos ambientes áridos del norte de Chile: Cuz-Cuz y El Tangue. Las características cuantitativas se evaluaron en arbustos de 5 años de edad. Para el análisis de datos se utilizó un enfoque Bayesiano, implementado usando el algoritmo de Gibbs. La sobrevivencia fue de 87,3 y 81,8% en Cuz-Cuz y El Tangue, respectivamente, confirmando el potencial de A. saligna en el norte de Chile. Las estimaciones de la moda a posteriori de la heredabilidad varió de h²=0,13 (sobrevivencia) a h²=0,25 (diámetro de copa). La ganancia genética (selección de árboles individuales) varió de 6 a 14% (intensidad de selección de 20%). Intervalo de credibilidad Bayesiano (p=95%) de las correlaciones genotipo-ambiente incluyeron el valor cero, indicando una significativa interacción para las características de sobrevivencia, diámetro de copa y altura. La selección de arbustos en plantaciones multipropósito, dependerá de la optimización de las características de interés a través de la selección de genotipos que responden bien en un sitio en particular.

This work aimed to study the variability in flowering of five populations of Eucalyptus cladocalyx established in the administrative region of Coquimbo, northern Chile. Flowering was recorded as a binary response trait in 30-month-old trees. Then, at first, a generalized linear model was fitted for analyzing provenance effect. Subsequently, genetic variability was studied within the best provenance by Bayesian inference via Gibbs sampling. Initially, two sites were considered: Caracas and Tunga Norte, in the littoral and interior area of the Choapa Province, respectively. In the littoral area, only 1.3% of the trees evidenced flowering events, while in Tunga Norte, this value was 23.43%. For this reason, only interior site was considered. The provenance effect was significant (p < 0.01), with Cowell (codified FDI-20411) being the population that evidenced a relative better flowering response, although it not was different of the trees from national plantations (FDI-Illapel). However, trees from a local population evidenced a high variability, having a mean response similar to other provenances. The flowering trait analyzed within the Cowell population, the selected provenance, was shown to be highly heritable (h² = 52.3%). Predicted genetic gain when considering two different breeding strategies varied from 36 to 40%. According to these results, it is possible that farmers can recover establishment costs of E. cladocalyx plantations as soon as possible whenever the selected trees are used for apicultural aims

Se analizó la variabilidad en el florecimiento de cinco poblaciones de Eucalyptus cladocalyx establecidos en la Región de Coquimbo. Se consideró al florecimiento como una respuesta binaria medida a los 30 meses de edad. Por lo tanto, se ajustó un modelo linear generalizado para analizar el efecto de procedencias. Posteriormente, se estudió la variabilidad genética dentro de la mejor procedencia, a través de inferencia Bayesiana, vía algoritmo de Gibbs. Inicialmente, se consideraron dos sitios, Hacienda Caracas y Tunga Norte, sector costero e interior de la Provincia de Choapa, respectivamente. En el sector costero, sólo un 1,33% de los árboles presentaron eventos de florecimiento, mientras que en Tunga Norte, este valor fue de 23,43%. Debido a este resultado, se consideró solo el sitio interior. El efecto de procedencias fue estadísticamente significativo (p < 0.01) siendo Cowell (codificada FDI-20411) la población que presentó una mejor respuesta relativa a los eventos de floración, aunque no fue diferente de los árboles de origen nacional (FDI-Illapel). Sin embargo, esta última población presentó una alta variabilidad, teniendo una respuesta media similar estadísticamente a otras procedencias. El florecimiento analizado dentro de la población de Cowell, población seleccionada, mostró ser altamente heredable (h² = 52,29%). La ganancia genética predicha, considerando distintas estrategias de selección, varió entre 36 y 40%. En función de estos resultados, es posible que el agricultor pueda recuperar al corto plazo el costo de establecimiento de la plantación de E. cladocalyx, siempre que los árboles seleccionados sean utilizados con fines melíferos

This study was undertaken to investigate bayesian methods to scientific inference in forest tree breeding. The Independence Chain (IC) and Gibbs sampling (GS) algorithms were applied on data sets from a field trial of Eucalyptus cladocalyx aiming to predict random family and additive genetic effects, respectively. The trial was carried out in the coastal area of Coquimbo Region, northern Chile. Diameter and height growth rate (TCD and TCA) were the data sets collected in a period of 30 months. Bayesian procedures were compared with the ranking obtained by Best Linear Unbiased Prediction (BLUP). BLUP and IC had similar family ranking, although the family selection based on credible intervals of the genoty-pic effects (bayesian framework) was clearly more intensive. Spearman rank correlation coefficients were high and significant (Ps= 0.99) between BLUP and GS. The estimates of heritability were moderate: h²= 0.42 (TCA) and h²= 0.43 (TCD). The traits had a significant correlation (Ts= 0.7). The estimated genetic gains, in relation to the experimental average, ranged from 17% to 28%. The greatest genetic gain and genetic diversity of the original diversity of the experimental populations may be achieved and maintained if the trees are selected for TCD. It was conclude hat the bayesian inference may be a useful tool in the genetic evaluation of forest trees, since it incorporates the variability of the genetic parameters by using posterior distributions

El objetivo de este estudio fue investigar los métodos bayesianos como una alternativa de inferencia científica aplicada a la evaluación genética forestal. Se usaron los algoritmos de Cadenas Independientes (IC) y de Gibbs (GS) en un conjunto de datos provenientes de un ensayo de Eucalyptus cladocalyx, para la predicción del efecto familiar e individual, respectivamente. El ensayo fue establecido en el sector costero de la Región de Coquimbo, norte de Chile. Se evaluó la tasa de crecimiento promedio de la altura (TCA) y el diámetro (TCD), medidas en un periodo de 30 meses. Los procedimientos se compararon con la mejor predicción linear inses-gada (BLUP). Se confirmó una significativa asociación entre el ranking familiar de BLUP e IC, aunque se evidenciaron mayores intensidades de selección al utilizar las regiones de credibilidad de los efectos genotípicos (enfoque bayesiano). Se obtuvieron altas y significativas correlaciones de Spearman (Ts= 0,9) entre BLUP y GS. Se obtuvieron moderadas heredabilidades individuales: h²=0,42 (TCA) y h² = 0,43 (TCD). Las características se correlacionaron significativamente entre sí (Fs = 0,7). Las ganancias genéticas, en relación al promedio del ensayo, variaron de 17% a 28%. Al seleccionar para TCD, mayor ganancia y diversidad genética puede ser alcanzada y mantenida que la diversidad encontrada en este ensayo de progenie. Se concluyó que la inferencia bayesiana puede ser una herramienta metodológica útil en la evaluación genética forestal, ya que permitió incorporar la variación de los parámetros genéticos a través de las distribuciones a posteriori