Contributions of genetic and environmental variance in early development of the Antarctic sea urchin Sterechinus neumayeri in response to increased ocean temperature and acidification

Abstract

Breeding designs such as the North Carolina II can be used to identify the sources of genetic and environmental variances in embryo performance. Here this approach is used for the Antarctic sea urchin S. neumayeri to explore how the contribution of sire and dam can influence the performance of cleavage stage embryos and blastulae, and how these contributions differ when exposed to stress from increased temperature and acidification. The interrelationship of sire–dam effects was also compared across developmental stages. The effects of warming (+3 °C) and acidification (−0.3 and −0.5 pHT units) on 24 sire–dam crosses were investigated. These stressors decreased cleavage success and the percentage of normal blastulae, with a negative interactive effect between stressors. The response to these factors differed among the sire–dam pairs indicating the influence of gamete compatibility. A positive genetic correlation indicated that genotypes that performed well as blastulae in low pH also performed well at increased temperatures. Performance at cleavage was a good predictor of performance at the later blastula stage. Significant dam by temperature interactions indicated differential performance among maternal half-siblings in response to increased temperature. Adaptation depends on additive genetic variance for stress tolerance being present in populations; however, there were no sire by stressor interactions found. This indicates that S. neumayeri will need to rely on phenotypic plasticity to persist through an ocean decreasing in pH and warming, at least with respect to early development.