The burden of big plant genomes : an elemental ecology perspective

The effect of genome sizes on plant distribution and ecosystem functions is of great importance. Plants exhibit significant variability in their genome sizes, which has cascading effects on the plant community. Larger genomes pose a considerable burden on many species, as much of the content of bigger genomes consists of non-coding or repetitive sequences that provide no functional value. Nevertheless, the plants still needs to allocate substantial resources to replicating and maintaining the genetic material. Nucleic acids in DNA are among the most nitrogen (N) and phosphorus (P) demanding molecules of the cell. Here, we test what effects a varying genome size has on the distribution of plant species and whether this association reflects underlying nutrient constraints and evolutionary pressures. The result of this study contributes to a better understanding of how genome sizes shape global plant distribution and biodiversity. We compiled a global dataset of foliar nutrient content and genome sizes for 520 species, including angiosperms and gymnosperms. To account for shared ancestry, we use a bayesian modeling approach, combined with quantile regressions to address the heteroscedasticity of the genome size distribution, and modeling the niche with the biogeochemical niche hypothesis. Our findings support that plants with big genome are more restricted in the soil types that they can occupy, as limitations in soil nitrogen and phosphorus constrain the resources available to sustain the bigger genomes. Consistent with this we find that foliar phosphorus and nitrogen contents increase with growing genome sizes. Using a biogeochemical niche modeling approach, we show that the plants with smaller genomes have a wider distribution, which decreases as genome size increases, supporting the claim of the burden of big genomes.