Monday (June 8) was my first day out at the NOAA Manchester Research Station in Washington State. Specifically, I’m working in the Kenneth K. Chew Center for Shellfish Research and Restoration. This shellfish hatchery is the result of collaboration between many groups and funding agencies, in particular the Puget Sound Restoration Fund (PSRF).
The hatchery (right) and algae greenhouse (left)
My project this summer is to raise oysters descended from three Puget Sound populations under common conditions in order to measure differences in fitness. This type of experimental design is commonly referred to as a “common garden”, and allows one to control environmental variables so that phenotypic disparities among individuals can be attributed to their genetic differences. My fitness metrics are reproductive output, survivorship at different life stages, and growth rate. I will also be taking DNA/RNA samples along the way to see if mortality is random in respect to genotype, or due to purifying selection. With the RNA, I plan to look at differences in gene expression to help detect cryptic differences in phenotype between these populations.
Three source populations for common garden experiment
This project is a collaboration with Steven Robert’s lab at the University of Washington, who previously conducted a reciprocal transplant experiment with offspring of wild oysters from these same populations. For that experiment, they outplanted the young oysters from each group at four different sites and measured growth rate, mortality, and reproductive characteristics. They observed significant variation at these metrics among populations and sites (informative slides and manuscript preprint available here). My experiment will be following up on these results by testing if population-level differences are consistent in a second generation under controlled environmental conditions.
As I’ve never raised shellfish before, this week has had a bit of a learning curve. Fortunately for me, the staff at the hatchery have been super helpful in showing me the ropes and advising on how to set up my experiment. I’m starting with about 100 adult oysters for each group (see lab notebook entries for data). These are the first generation (F1) offspring of wild oysters, and have been living in common conditions their entire lives- mostly hanging off the docks near the hatchery. Their offspring will be 2nd generation (F2) from the original broodstock, and should have any influence from maternal effects erased.
The adults were brought in to the hatchery on May 28 and placed in three separate buckets to avoid cross fertilization. To maximize genetic diversity and minimize the chance that one male fertilizes all of the females, I split each group into 5 buckets of ~20 oysters. These “families” will be marked, so that I can genotype them later and follow their offspring’s success throughout the experiment. Their water temperature was switched to a balmy 20°C this week, which will encourage them to start spawning and producing larvae.
(sorry for the lack of pictures, I’ll take some and put them up soon!)