Data from: fish (eggs) out of water: evolutionary divergence in terrestrial embryonic plasticity in Trinidadian killifish

Research has shown that externally laid eggs are often responsive to environmental signals. How such embryonic plasticity evolves is unclear. In Trinidad, the killifish (Anablepsoides hartii) are found in communities with and without predators. Killifish inhabit shallower, ephemeral habitat in sites with predators. Such shifts increase the exposure of eggs to air and possible desiccation. We compared embryonic plasticity between communities by rearing eggs terrestrially on peat moss or in water. The timing of hatching did not differ between communities when eggs were reared in water. Eggs from sites with predators responded to terrestrial incubation by hatching significantly earlier compared to water reared eggs. These responses were weaker in sites with no predators. Such divergent trends show that the presence of predators is associated with shifts in embryonic plasticity. Our results provide new insights into the factors that favor the evolutionary transition between life on water vs. land.