Marker-Based Quantitative Genetics in the Wild?: The Heritability and Genetic Correlation of Chemical Defenses in Eucalyptus

Abstract

Marker-based methods for estimating heritability and genetic correlation in the wild have attracted interest because traditional methods may be impractical or introduce bias via G 3 E effects, mating system variation, and sampling effects. However, they have not been widely used, especially in plants. A regression-based approach, which uses a continuous measure of genetic relatedness, promises to be particularly appropriate for use in plants with mixed-mating systems and overlapping generations. Using this method, we found significant narrow-sense heritability of foliar defense chemicals in a natural population of Eucalyptus melliodora. We also demonstrated a genetic basis for the phenotypic correlation underlying an ecological example of conditioned flavor aversion involving different biosynthetic pathways. Our results revealed that heritability estimates depend on the spatial scale of the analysis in a way that offers insight into the distribution of genetic and environmental variance. This study is the first to successfully use a marker-based method to measure quantitative genetic parameters in a tree. We suggest that this method will prove to be a useful tool in other studies and offer some recommendations for future applications of the method.

Contrasting patterns of morphological and physiological differentiation across insular environments: phenotypic variation and heritability of light-related traits in Olea europaea

“…In our study system, molecular data suggest that populations were established by multiple founders (García-Verdugo et al 2010;García-Verdugo et al in review), which enhances a mixture of relatedness within populations and thus favors significant variance (Ritland 2000). In addition, sampled individuals were on average 15-20 m apart, an optimal distance with regard to maximizing actual variance in other woody species (Klaper et al 2001;Andrew et al 2005).…”

“…To provide a conservative estimate of sampling error, significance of heritability estimates was determined by bootstrapping over individuals (see Andrew et al 2005 for a comparison of different approaches). Heritability estimates were deemed significant if 95% of the bootstrapped values (n = 100) were positive.…”

Palatability mapping: a koala's eye view of spatial variation in habitat quality

“…Fine-scale spatial autocorrelation was observed among FPC concentrations of each species considered. FPC concentrations are highly heritable in Eucalyptus (Andrew et al 2005), and Andrew et al (2007) showed in E. melliodora that strong spatial autocorrelation in FPC concentrations overlaid a highly congruent spatial structure in genetic variance. The strength and scale of autocorrelation observed in this study for FPCs are comparable to those in E. melliodora and those for genetic markers in Tasmanian E. globulus (Skabo et al 1998), and are probably largely a product of isolation by distance (Heywood 1991).…”

The genetic basis of foliar terpene yield: Implications for breeding and profitability of Australian essential oil crops

“…nutrient availability (Muzika 1993), water stress (Delfine et al 2005), atmospheric CO 2 concentrations (Peñuelas et al 1997), seasonality and temperature (Emara and Shalaby 2011;Peñuelas et al 1997), herbivory (Paré and Tumlinson 1999), mediated by methyl jasmonate (Martin et al 2003) (but not eucalypts (Henery et al 2008). However, in all woody species that have been examined to date, the genetic component of variation (expressed as the narrow sense heritability) has, without exception, been high (h 2 =0.6-0.9) (Andrew et al 2005(Andrew et al , 2007Doran and Matheson 1994;Franklin and Snyder 1971;Han and Lincoln 1994;Hanover 1966aHanover , 1966bO'ReillyWapstra et al 2011;Rockwood 1973;Squillace 1971). High heritability has been observed for specific terpenes e.g.…”

“…High heritability has been observed for specific terpenes e.g. foliar 1,8-cineole concentrations in Eucalyptus kochii (Barton et al 1991); and Eucalyptus melliodora (Andrew et al 2005), as well as total foliar terpene concentrations in Eucalyptus camaldulensis (Doran and Matheson 1994) and Melaleuca alternifolia (Doran et al 2006). The high heritability and large variation of foliar terpene concentrations in Myrtaceae raises a number of questions: How and why are foliar terpene concentrations so variable?…”