Award: OCE-1041222

We used a unique combination of field collections, experimental laboratory culture, and genetic data to address for the first time issues that are at the forefront of modern climate biology: Will organisms be able to evolve in response to rapidly changing climate conditions? If so, what will be the molecular mechanisms of adaptation? In our work, we take the next step by using newly developed DNA sequencing methods to measure natural selection in action in response to experimental ocean acidification. This is a first in the field of genomics: we measure selection due to climate change in a single generation from the standing genetic variation in natural populations. We measure genetic change at over 19,000 places in the sea urchin genome to report a remarkable finding. Sea urchin larvae maintain normal growth in low pH conditions by means of natural selection acting on specific genes that give them improved performance in stressful environmental conditions. These results are the first to link resistance to the negative effects of acidification to genetic changes across the genome. The presence of these adaptive alleles is likely due to the high environmental variation in this coastal upwelling ecosystem, high dispersal among regions, and high mutation rate. These characteristics are common to many other highly dispersing organisms, such as many plant and migratory animal species, suggesting such organisms may have some scope for adaptation to future climate conditions. Last, we note the pivotal point that adaptive capacity is a double-edged sword: it may allow future evolution, but only at a significant demographic cost to the evolving population. Populations that are already at low numbers because of climate or other anthropogenic stresses may not have the demographic scope to respond Last Modified: 11/29/2013 Submitted by: Stephen R Palumbi