Body size often declines with increasing temperature. Although there is ample evidence for
this effect to be adaptive, it remains unclear whether size shrinking at warmer temperatures
is driven by specific properties of being smaller (eg, surface to volume ratio) or by traits that
are correlated with size (eg, metabolism, growth). We used 290 generations (22 months) of
artificial selection on a unicellular phytoplankton species to evolve a 13-fold difference in
volume between small-selected and large-selected cells and tested their performance at 22° …