Genotype-by-environment interactions during early development of the sea urchin Evechinus chloroticus

The increase in seawater temperature due to anthropogenic climate change is likely to affect population persistence and changes in distributional ranges of marine species. Adaptation to warmer environmental conditions will be determined by the presence of tolerant genotypes within a population. The present study determined the genotype-by-environment (G x E) interactions during early development of the New Zealand sea urchin Evechinus chloroticus cultured at 18 degrees C (mean annual temperature), 21 degrees C (ambient summer temperature) and 24 degrees C (+ 3 degrees C above ambient summer temperature). The experiment was performed in 3 experimental blocks using gametes from 3 males and 3 females crossed in all combinations (North Carolina II cross-breeding design), resulting in 9 families per experimental block (i.e., total of 27 families). Differences between female and male identities were quantified during cleavage and gastrulation: Reaction norms (i.e., interaction plots) showed a clear G x E interaction, with some genotypes performing better than others at high temperatures. Heritability during gastrulation was 0.51, indicating that 51 % of the variability corresponds to genetic variation. Overall, the present study shows that seawater temperature has a negative effect on early development of E. chloroticus; however, there are resilient genotypes in the studied population that could provide the genetic potential to adapt to future ocean conditions.