Diego Moura-Campos, Meng-han Joseph Chung, Edward Lawrence, Michael Jennions, Megan Head

With climate change, animals face both rising temperatures and more variable food availability. Many species have evolved an adaptative response to historic variation in food availability: they grow faster after a period of diet restriction (“compensatory growth”). However, higher temperatures may reduce the capacity for compensatory growth in ectotherms because individuals require more resources to support their increased metabolism. We experimentally tested how higher temperature affects compensatory growth by raising guppies (Poecilia reticulata) at a high or control temperature, and on a normal or temporarily restricted diet during early development. At the control temperature guppies on the restricted diet grew faster once their diet returned to normal. Both sexes showed compensatory growth. At the high temperature, both sexes also increased their growth rates after dietary restriction ended, but the life history outcomes differed. Males at the high temperature matured earlier and were smaller than males reared at the control temperature. In contrast, females at the high temperature matured later and were bigger than females at the control temperature. Our study highlights that rising temperatures could reduce the ability of fish to compensate for periods of low food availability, and that males and females can have different responses to the same environmental stressors.