Data from: The evolution of gestation length in eutherian mammals

Eutherian mammals exhibit striking variation in their gestation lengths,
which has traditionally been linked to and allometrically scales with
variation in other life history traits, including body mass and lifespan.
To understand how the phenotypic landscape of gestation length variation,
including its associations with body mass and lifespan variation, changed
over mammalian evolution, we conducted phylogeny-informed analyses of 845
representative extant species. We found that gestation length
substantially differed in both whether and how strongly it was associated
with body mass and lifespan across mammalian clades. For example,
gestation length was not associated with lifespan or body mass in
Chiroptera and Cetacea but was strongly associated only with body mass in
Carnivora. We also identified 52 evolutionary shifts in gestation length
variation across the mammal phylogeny and 14 shifts when we jointly
considered variation of all three traits; six shifts were shared. Notably,
two of these shifts occurred at the roots of Cetacea and Pinnipedia,
respectively, coinciding with the transition of these clades to the marine
environment. These results suggest that evolutionary constraints on
gestation length have varied substantially across mammalian phylogeny and
that the genetic architecture of gestation length may differ between
mammal clades.