Figure Legends:
Figure 1 A): Illustrates carbon assimilation as a function of leaf
temperature for a single exemplar species, Cynophalla flexuosa .
The black and gray colours indicate Eq. 1 and Eq. 2 model fits to the
diamond-shaped data points, respectively. Eq. 1 was used to calculate
Topt, Popt, and Ω; Eq. 2 was used to
calculate Topt, Popt, and
Tmax; B) Illustrates the quantum yield
(FV/FM) as a function of temperature
treatment used to calculate the Tcrit,
T50, and T95 heat tolerance (represented
as shaded vertical lines) using Eq.’s 3 and 4 for Cynophalla
flexuosa . The curved shaded lines show 1 of 100 bootstrapped iterations
Figure 2: We address the assumption that PSII heat tolerance can promote
greater carbon assimilation at higher temperature. Figure the change in
a given trait between a species with a low heat tolerance (solid line)
and high heat tolerance (dashed line). Hypothesis 1 (H1) proposes
Tmax is constrained by PSII heat tolerance, which could
be associated with an increase in Ω (short dashed line), an increase in
Tmax (long dashed line), or a combination of the two; H2
is that high PSII heat tolerance promotes greater Ω indicative of a
thermal generalist strategy of carbon assimilation; H3 that high PSII
heat tolerance promotes higher Popt characteristic of
species with “fast” carbon acquisition strategies; and 4) PSII heat
tolerance promotes higher Topt
Figure 3: (top) The mean Topt (circles),
Tcrit (left edge of the box), Tmax(triangles), T50 (vertical line in center of box), and
T95 (right edge of box) for our dataset. The coloured
boxes depict the thermal safety margins of PSII heat damage. Dotted
lines connect the carbon assimilation traits; (middle) Box plots of
temperatures that correspond to the heat tolerance and carbon
assimilation parameters of each species; (bottom) The relative
temperatures of Topt, Tcrit,
Tmax, T50, and T95 for
each species arranged from highest to lowest Tmax
Figure 4: Here we illustrate the significant correlations among A) Ω and
Tmax, and B) Ω and Topt photosynthetic
traits after correcting for phylogenetic independence. Each figure shows
the phylogenetically independent contrasts for each trait with the
phylogenetically corrected Pearson’s correlation coefficient and
significant in the bottom left corner. Solid lines within plots indicate
significant correlations
Figure 5: Here we illustrate the correlations among PSII heat tolerances
and photosynthetic traits after correcting for phylogenetic
independence. The top rows panels A-C correspond to hypothesis 1, panels
D-F correspond to hypothesis 2; panels G-I correspond to hypothesis 3;
and panels J-L correspond to hypothesis 4. Each figure shows the
phylogenetically independent contrasts for each trait with the
phylogenetically corrected Pearson’s correlation coefficient and p-value
in the bottom left corner. No line within a plot indicates no
significant correlation, solid lines indicate significant correlations,
and the dashed line indicates a marginally insignificant correlation