Evolutionary shifts in condition-transfer effects but not anticipatory maternal effects in Trinidadian killifish ( Anablepsoides hartii )

Abstract

Transgenerational plasticity (TGP) shapes offspring phenotypes independent of changes in DNA sequence. However, it remains unclear whether transgenerational plasticity primarily reflects adaptive anticipatory adjustments to predicted future environments or condition-dependent carryover from the parental energetic state. Because traits differ in their functional roles within life-history architecture, selection may favour distinct cross-generational mechanisms depending on the ecological context. We tested these alternatives using Trinidadian killifish (Anablepsoides hartii), which are locally adapted to either high-predation (HP) or predator-free killifish-only (KO) environments. Predation regime structures population density and per capita resource availability, making food availability an ecologically realistic proxy for the pathways through which predation regimes influence maternal conditions and transgenerational responses. Therefore, we experimentally manipulated the maternal (F2) and offspring (F3) food environments using a split-brood design and quantified the offspring body mass, body condition and egg development rate. Offspring body mass was overwhelmingly determined by the immediate food environment. By contrast, the egg development rate was strongly influenced by the maternal food environment. This condition-transfer effect was much stronger in the high-predation population. We found little evidence of anticipatory effects for any trait. Our results indicate that the evolution of condition-dependent maternal effects may represent a primary adaptive pathway when selection acts strongly on life-history pacing, helping reconcile mixed empirical support for anticipatory transgenerational plasticity.