Phylogenetic contrasts:
Only species with at least one measure from each caste on Antweb.org were used in analysis; species of the same species complex were substituted if the species in the phylogeny was not fully represented in Antweb.org; species complex information was obtained from species information in Antwiki.org. The worker ratio was the largest divided by the smallest worker head width, while the sexual ratio was the mean gyne head width divided by the mean male head width. The gyne:worker ratio was calculated as the average gyne size divided by the minimum worker size.
Genus-level phylogenies (Pheidole: (Moreau 2008), Pogonomyrmex: (Johnson and Moreau 2016)) were used to address non-independence of species.
Relationships of size variation between castes were tested using a linear model with phylogenetic correction. Phylogenetic correction was done using independent contrasts as calculated using the crunch function in the caper package in R (Orme et al. 2018).