In this paper, I focus on the latitudinal distributions of
temperature limits of phytoplankton, by analyzing a
dataset compiled from laboratory culture experiments
using linear mixed-effect models. I evaluate three hypotheses
related to the patterns of phytoplankton thermal
limits. The first is whether the environmental temperatures
affect phytoplankton thermal limits. Secondly,
Janzen’s rule states that the thermal breadth often
increases with latitude owing to the fact that the minimal
The third question is whether there is a tradeoff between
maximal growth rate and thermal breadth. A reasonable
hypothesis, based on the supposed tradeoff between the
evolution of an optimal enzyme structure under the optimal
temperature and enzyme functions under non-optimal temperatures,
is that a generalist that can survive under a wide
range of temperatures should grow slower than a specialist
at the optimal temperature of the specialist (Levins, 1964).
However, Huey and Hertz (Huey and Hertz, 1984) show a
counter-example in lizards whereby the fastest species can
also tolerate the broadest thermal ranges. What patterns
exist for phytoplankton remains an interesting problem