Figure 1: The relationship between plant height and rates of molecular evolution in angiosperms.

Differences in the logarithms of plant height and rates of molecular evolution were measured for sister pairs of angiosperm families. Regressions through zero show a significant negative association between plant height and synonymous substitution rates measured from protein-coding genes in the chloroplast genome (a), and between plant height and substitution rates in rRNA genes in the nuclear genome (b). In each panel, the best-fit line (dark grey) was estimated using linear regression through the origin, with the 95% confidence intervals around this line shown in light grey (see main text).