Data from: Fertilization mode covaries with body size

The evolution of internal fertilization has occurred repeatedly and
independently across the tree of life.  As it has evolved,
internal fertilization has reshaped sexual selection and the covariances
among sexual traits such as testes size and gamete traits. But it is
unclear whether fertilization mode also shows evolutionary associations
with traits other than primary sex traits. Theory predicts that
fertilization mode and body size should covary, but formal tests with
phylogenetic control are lacking. We used a phylogenetically-controlled
approach to test the covariance between fertilization mode and adult body
size (while accounting for latitude, offspring size, and offspring
developmental mode) among 1,232 species of marine invertebrates from 3
phyla. Within all phyla, external fertilizers are consistently larger than
internal fertilizers: the consequences of fertilization mode extend to
traits that are only indirectly related to reproduction. We suspect that
other traits may also coevolve with fertilization mode in ways that remain
unexplored.