The amount of nuclear DNA varies over a thousand-fold among plant species. Polyploidy accounts for some of this variation, but most of it is due to differences in genome size (the amount of DNA in one complete set of chromosomes). Genome size may influence important life-history strategies. A few characteristics of invasive species include short generation times, small seeds that can be widely dispersed, and high relative growth rates. In a previous study of twenty pine (Pinus) species, a discriminant analysis between invasive and non-invasive species based on their reproductive attributes was negatively correlated with genome size. We hypothesized that genome size would also be negatively correlated with relative growth rate. Results from a comparative relative growth rate study of thirty Pinus species supports the hypothesis that species with smaller genome sizes have higher relative growth rates. A proposed mechanism of how genome size influences relative growth rate is also presented.

Key words: genome size, invasive species, nuclear DNA content, Pinus