Coral reefs are
complex and dynamic systems that are geologically robust and have persisted
through major climactic shifts, yet they are highly sensitive to environmental
perturbations on ecological timescales. The Earth’s climate is changing rapidly
mostly due to anthropogenic disturbances. The average temperature of the ocean
is projected to increase at least 3°C by the end of the century, and there is a progressive oceans acidification (cecrising pH) due to increasing atmospheric CO2, with potentially
serious effects on the structure and function of coral reef systems. It is unclear
if and how reef species, such as tropical fishes, will adapt to these rapid
changes in ocean temperature. In particular, tropical species may be more
vulnerable to rising temperatures and decrising pH than species from cooler climates, because
they are already living close to their thermal limits. Transgenerational
acclimation is a form of non-genetic inheritance in which the environmental
conditions experienced by one-generation influences the performance of future
generations in that environment. New studies show that the performance of
juvenile fish at higher water temperatures is significantly improved when their
parents also experienced the warmer temperature. The molecular mechanisms
responsible for transgenerational thermal acclimation, and how it is controlled,
are currently unknown. Genomic DNA methylation is a form of epigenetic
inheritance that cells use to control gene expression, and recent evidence
suggests that genome methylation can be driven by external signals in cells
after birth as well as in adult cells. This raises the intriguing possibility
that DNA methylation can serve as a mechanism for genomes to rapidly adapt to
changing environments. Here we propose a unique multi-generational manipulative
experiment for a common coral reef fish, Acanthochromis
polyacanthus, with genome-wide measurements of gene expression and DNA
methylation. Using an integrative analysis, we seek to identify molecular
pathways responsible for transgenerational acclimation to rising ocean
temperatures and to test the hypothesis that genomic DNA methylation serves as
a central mechanism mediating transgenerational acclimation to climate change.