An Ecological-Evolutionary Investigation of Phenotypic, Genetic, and Environmental Variation and Correlations Among Reproductive Traits of Tall Goldenrod (Solidago altissima).

Although fitness-related traits are expected to be under strong selection, traits related to reproduction are often quite variable within plant populations. We used data from two large greenhouse experiments to quantify phenotypic, genetic, and environmental variation, as well as genetic tradeoffs that might help explain the maintenance of within-population variation in four traits related to sexual or vegetative reproduction in tall goldenrod (Solidago altissima). The goldenrod population exhibited high levels of both phenotypic and genetic variation for capitulum (flower head) number and size, seed production, and rhizome growth. Significant negative genetic correlations were present between the number of capitula and size of capitula-but only at high-nutrient levels-and between seed production and rhizome growth when nutrients were more limiting. In total, negative genetic correlations may act to maintain variation in fitness-related traits in goldenrod populations-a phenomenon we suspect may be shared by other herbaceous plant species as their populations experience variation in environmental factors, such as nutrient levels, among sites or over the course of ecological succession within a site.