Supplementary Material
Figure S1. Distribution of habitat preference and growth form across the diatom phylogeny. Tip labels
denote species' phenotype. Growth form is first column and habitat preference second column. Branch
colors denote ancestral state reconstruction of growth form estimated with the favored symmetric
variable-rate model (see Table 3). Circles at nodes denote ancestral state reconstruction of rate classes
according to the same model (see Table 3).
Table S1. Sources for coding of habitat, growth form, and combined phenotypes for 281 diatoms and
Bolidomonas.
Table S2. Constant-rate and variable-rate models for the evolution of habitat occupancy. Models are
ordered based on their average Akaike weights (ωi) denoting the relative likelihood of each model.
Refer to Fig. 1A-B for diagrammatic representation of the models. This is the same analysis as reported
in the main text with the exception that Attheya species were coded as benthic.
Table S3. Two trait models for the evolution of the combined habitat + growth form phenotypes.
Models are ordered based on their average Akaike weights (ωi) denoting the relative likelihood of each
model. Models of independent evolution outperform the dependent model where transitions between
states in one trait are conditioned on the state of the other trait. Refer to Fig. 1D for diagrammatic
representation of the models. This is the same analysis as reported in the main text with the exception
that Attheya species were coded as benthic.
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