COS 49-4
Transgenerational plasticity depends on the cue
Evidence for non-genetic transgenerational effects is abundant. In a wide variety of species, parents pre-program their offspring based on the environment that they experienced. However, not much is known about the evolution of these effects, or what drives them. Theory suggests that the ability of parents to predict the offspring's environment is a critical component, though few empirical studies have explored this. Sheepshead minnows, Cyprinodon variegatus, exhibit thermal TGP such that the temperature experienced by parents determines the thermal performance of their offspring. To assess the importance of environmental predictability, we asked whether holding sheepshead minnows from Florida at a summer temperature (32°C) over 10, 30, 45, and 60 days influenced the magnitude of the transgenerational effect. We also evaluated changes in offspring reaction norms when parental temperatures were reduced to 24°C after 100 days.
Results/Conclusions
As previously observed, after holding parents at high and low temperatures for 10 days, offspring growth was similar, within offspring temperature, regardless of parent origin (i.e., only phenotypic plasticity observed). After exposing parents to 32°C for 30 days, however, a strong pre-conditioning effect was measured in the offspring — offspring at 32°C grew faster if they came from parents that experienced 32°C water and vice versa. Contrary to expectations, holding parents for longer at 32°C actually reduced the magnitude of the transgenerational effect. Returning 32°C parents to 24°C water led to offspring with growth reaction norms similar to the control group (parents always exposed to 24°C). The thermal habitat characteristics may explain the varying effect sizes over different exposure times. These results highlight the dynamic nature of transgenerational effects.