Data from: Niche conservatism over deep timescales and diverse niche axes in land vertebrates

Aim: There has been considerable interest in niche conservatism, the idea
that ecological variables are similar among related species. Much research
has focused on climatic niches of recently diverged species, rather than
deeper timescales or non-climatic niche axes. Furthermore, it has been
suggested that conservatism disappears over deeper timescales, and is
greater in alpha niche traits (like diet and microhabitat) than beta niche
variables (like climate). Here, we test these two ideas by comparing
patterns of phylogenetic conservatism among 10 niche variables across
major clades of land vertebrates. Location: Global. Time period: Present
to 350 million years ago. Major taxa studied: Tetrapods, including
amphibians, mammals, lepidosaurs (including lizards and snakes), turtles,
crocodilians, and birds. Methods: The 10 niche variables included four
alpha niche components (diet, diel activity, habitat, body temperature)
and six beta niche components (related to climatic temperature and
precipitation). We analyzed these variables on time-calibrated phylogenies
with similar taxon sampling (~1700 species), using phylogenetic signal
(lambda) to estimate conservatism, along with the D-statistic and
estimates of evolutionary rates. Results: Phylogenetic signal was
generally strong across all variables, with lambda generally >0.80
(with 1.0 representing maximum signal). Nevertheless, mean phylogenetic
signal was lower in beta niche traits than alpha niche traits (based on
lambda and especially the D-statistic), and alpha niche traits showed
significantly slower rates of evolution. Main conclusions: We address two
long-held views in the literature on niche conservatism, rejecting one but
supporting the other. We show that phylogenetic signal does not disappear
over deep timescales for many important niche variables, even over 350
million years. We also generally support greater conservatism in alpha
niche traits than beta niche traits over hundreds over millions of years,
a pattern that was previously suggested (but not explicitly tested) based
on closely related species.