DOI: 10.5061/dryad.d7wm37q7n
title: Bigger genomes provide environment-dependent growth benefits in grasses

description: Increasing genome size (GS) is associated with slower rates of DNA
 replication and greater cellular nitrogen and phosphorus demands.
 Nevertheless, plant species vary enormously in GS. Using data on grass
 species’ climatic niches and growth rates under different environmental
 conditions, we tested for growth costs or benefits associated with GS. We
 found that evolutionary history, photosynthetic pathway and life-history
 all influence the distribution of grass species’ GS. GS was constrained in
 annual and C4 species, the latter allowing for small cells necessary for
 C4 leaf anatomy. We found that larger GS were advantageous under high
 nitrogen availability and, for perennial species, low growth-season
 temperature. Increased GS benefits are likely due to associated larger
 cell sizes, allowing rapid biomass production where soil fertility meets
 nitrogen demands or when growth occurs via temperature-independent cell
 expansion. Our findings reveal that GS is a globally important predictor
 of grass performance dependent on environmental conditions.
description: # Bigger genomes provide environment-dependent growth benefits in grasses
 ## Description of the data and file structure ### Dataset descriptions
 grass.niche.data.csv = Species-level data on mean grass environmental
 niches (relating to temperature, precipitation and soil nitrogen), life
 history and photosynthetic pathway grass.RGR.csv = Species-level data on
 grass relative growth rate under different environmental conditions, as
 well as life history and photosynthetic pathway grass.phylogeny.tre =
 Maximum clade credibility phylogeny of 660 grass species (subset for the
 study species for the niche analyses; from [Forrestel
 2015](https://www.proquest.com/openview/64a2210dd62af9f40a72ec5f817a5073/1?pq-origsite=gscholar&cbl=18750)) N.B. Data on genome size (1C values) for the study species can be accessed at the Plant DNA C-values database [https://cvalues.science.kew.org/](https://cvalues.science.kew.org/) ### Explanation of abbreviations/code names used in column headings grass.niche.data.csv columns: species – Species name phylo.name – species name that matches the tip.labels of the phylogeny (‘grass.phylogeny.tre’) PP – photosynthetic pathway (C3 or C4) LH – life history (Annual or Perennial) bioclim10.mean – mean values of temperature of warmest quarter (Bioclim 10; degrees celcius) bioclim15.mean - mean values of precipitation seasonality (Bioclim15; coefficient of variation) soilN.med – median values of soil N density (g/m2); NA indicates missing values grass.RGR.csv columns: phylo.name rgr – relative growth rate (g g-1 day-1) experiment – The experimental treatment with four possible levels: Control, D (‘reduced watering’ treatment), N (‘reduced nitrogen’ treatment), T (’reduced temperature’ treatment). Descriptions of control and treatment conditions can be found in the manuscript pp – photosynthetic pathway (C3 or C4) lh– life history (Annual or Perennial) tribe – Grass tribe the species belongs to   **Sharing/Access information** Links to other publicly accessible locations of the data: [https://www.worldclim.org/data/bioclim.html](https://www.worldclim.org/data/bioclim.html)  - WorldClim data website (where temperature and precipitation values were acquired) [https://cvalues.science.kew.org/](https://cvalues.science.kew.org/) - Plant DNA C-values database (where published grass 1C values were acquired) [https://daac.ornl.gov/ISLSCP_II/guides/islscp2_soils_1deg.html](https://daac.ornl.gov/ISLSCP_II/guides/islscp2_soils_1deg.html) - SLSCP II Global Gridded Soil Characteristics (where soil N density data was acquired) #### **Code** The R script included (‘**MCMCglmm example script.R**’) runs through importing data and phylogeny, running a Markov chain Monte Carlo generalised linear mixed effects (MCMCglmm) model, plotting the data and results from the model, and the generation of R2 values for the model too. This code uses the data for soil N density, and determines the effect of soil N density, grass life history and photosynthetic pathway on grass genome size.