Phylogenetic patterns and trait correlations
Fig. 4 shows the phylogenetic tree of the 144 identified species in our
dataset, color coded by T50 standardized to sea level
using the linear relationship with elevation shown in Fig. 1. There are
some distinct clusters of related species with similar trait values,
such as the high T50 values of the species ofZamia , the relatively high heat tolerance of the Moraceae
(Ficus spp, Castilla elastica, Poulsenia armata , andBrosimum guianense ), and the relative low heat tolerance of the
Annonaceae. However, the phylogenetic signal on T50 was
not statistically significant with α of 0.05 (Blomdahl’s K= 0.11,P =0.06; Pagel’s λ=0.51, P =0.08), suggesting that across
the phylogenetic tree related pairs of species were not significantly
more similar to each other than random pairs. TCritlikewise did not show a significant phylogenetic signal (K=0.11,P =0.05; λ =0.17, P =0.99. Fig. S7). In fact, the species
with the highest and lowest TCrit values among native
lowland trees both belong to the Urticaceae: 44.0°C for Pourouma
bicolor , and 50.8°C for Cecropia longipes .
The leaf functional traits all had phylogenetic signals, with the
exception of Blomdahl’s K for leaf length. τ was also phylogenetically
structured (K=0.18, P =0.022; λ=0.90, P <0.001).