Fig 1.
The TPC of ectotherm metabolic traits, as described by the Sharpe-Schoolfield model [5].
(A) Tpk (K) is the temperature at which the curve peaks, reaching a maximum height that is equal to Bpk (in units of trait performance). E and ED (eV) control how steeply the TPC rises and falls, respectively. B0 (in units of trait performance) is the trait performance normalised at a reference temperature (Tref) below the peak. In addition, Wop (K), the operational niche width of the TPC, can also be calculated a posteriori as the difference between Tpk and the temperature at the rise of the TPC where B(T) = 0.5 ⋅ Bpk. We note that we use Wop instead of a metric that captures the entire TPC width because previous studies have shown that species generally experience temperatures below Tpk [6, 7]. Thus, Wop is a measure of the thermal sensitivity of the trait near typically experienced temperatures. (B) TPCs of individual- and population-level traits (such as rmax) are usually well described by the Sharpe-Schoolfield model. The raw data for panel B are available at https://doi.org/10.6084/m9.figshare.12816140.v1. TPC, thermal performance curve.
Fig 2.
Moderate to strong phylogenetic heritability can be detected in all TPC parameters, across phytoplankton and prokaryotes.
The 3 circles of each radar chart correspond to phylogenetic heritabilities of 0, 0.5, and 1. Mean phylogenetic heritability estimates—as inferred with MCMCglmm—are shown in purple, whereas the 95% HPD intervals are in dark grey. Note that we transformed all TPC parameters so that their statistical distributions would be approximately Gaussian. The data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1. HPD, highest posterior density; TPC, thermal performance curve.
Fig 3.
Change in mean subclade disparity in thermal sensitivity through time.
Shaded regions represent the 95% confidence interval of the resulting trait disparity from 10,000 simulations of random Brownian evolution on each respective subtree (subset of the entire phylogeny). The dashed line stands for the median disparity across simulations, whereas the solid line is the observed trait disparity. The latter is plotted from the root of the tree (t = 0) until the most recent internal node. The reported P values were obtained from the rank envelope test [40], whose null hypothesis is that the trait follows a random walk in the parameter space. Note that instead of a single value, a range of P values is produced for each panel, due to the existence of ties. In general, species from evolutionarily remote clades tend to increasingly overlap in thermal sensitivity space (mean subclade disparity exceeds that expected under Brownian motion) with time. The raw data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1.
Fig 4.
Distributions of thermal sensitivity estimates of rmax for the largest (most species-rich) phyla of this study.
In general, more variation can be observed within than among phyla. The data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1.
Fig 5.
Variation in the evolutionary rate of thermal sensitivity across the phylogeny.
Rates were estimated by fitting the stable model of trait evolution to each dataset and were then normalised between 0 and 1. Most branches exhibit relatively low rates of evolution (orange), whereas the highest rates (red and brown) are generally observed in late-branching lineages across different clades. The raw data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1.
Fig 6.
Projection of the phylogeny into thermal sensitivity versus time space.
The values of ancestral nodes were estimated from fits of the stable model. Yellow lines represent the median estimates, whereas the 95% credible intervals are shown in red. is the estimated central tendency for each panel, whereas the existence of a linear trend towards lower/higher values is captured by the reported slope. Parentheses stand for the 95% HPD intervals for
and the slope. All estimates were obtained for ln(E) and ln(Wop), but the parameters are shown here in linear scale. The inset figures show the density distributions of E and Wop values of extant species in the dataset. The arrow in panel D shows an example of a whole clade shifting towards high Wop values, without being attracted back to
. The raw data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1. HPD, highest posterior density.
Fig 7.
E values weakly decrease with absolute latitude.
23% of the variance is explained by latitude and trait identity, which increases to 58% if species identity is added as a random effect on the intercept. Note that values on the vertical axis increase exponentially. The data underlying this figure are available at https://doi.org/10.6084/m9.figshare.12816140.v1.