The latitudinal patterns of minimal and maximal
growth temperatures of marine phytoplankton were
similar to those of optimal temperatures (Fig. 2B and D).
Cell size did not play a role in affecting minimal and
maximal growth temperatures of marine or freshwater
phytoplankton. The signal of phyla was evident for
minimal growth temperatures of marine phytoplankton
(Table I). After controlling latitude constant, the minimal
growth temperatures of dinoflagellates and cyanobacteria
were significantly higher than those of diatoms (P,
0.001; Fig. 2C). The maximal growth temperature of
chlorophytes was also significantly higher than that of
diatoms (P, 0.001). For freshwater phytoplankton, the
patterns were not evident. Visual inspection suggested
that the maximal growth temperatures of freshwater
phytoplankton were often higher than those of marine
ones (Fig. 2D). The minimal and maximal growth temperatures
of freshwater phytoplankton were relatively invariant
with latitude (Fig. 2B and D)