How strange to call this planet 'Earth' when quite clearly it is ocean. Arthur C. Clarke

Research Interests




General:


I am interested in eco-evolutionary dynamics in marine ecosystems. This includes:
  • how organisms evolve at the same pace as ecological processes
  • environmental effects of intraspecific phenotypic variation
  • coevolutionary dynamics 

I will explore these interests in a predator-prey interaction in intertidal habitats: predatory dogwhelks (Nucella spp.) that drill and consume mussels (Mytilus spp.).

Questions I like to ask:


How does intraspecific trait variation affect communities?
How are plasticity and local adaptation dependent on ecological context (biotic or abiotic)?
How broad and large are the effects of plasticity or genetic adaptation in a community? 
How does trait change due to phenotypic plasticity compare with trait change due to genetic adaptation?
How do anthropogenic influences such as harvest affect traits, evolution, and ecosystems?


Current research:


I am doing research to explore population-level trait variation in intertidal dogwhelks (Nucella ostrina). I want to understand how their drilling traits may be locally evolving to match the prey available to them and if this corresponds with their local environment, such as the acidity of seawater in their habitats. I expect to find differences in their drilling abilities, and I seek to understand how this may affect intertidal prey communities.

Dogwhelks: predators in a model system for studying local adaptation
Nucella ostrina dogwhelks are boring predators, but they are not uninteresting. A dogwhelk consumes its prey by using acid and its radula to drill through mussel shells and consume the soft viscera (Fig 1). Dogwhelks are important predators because they can consume large numbers of mussels, a foundational species in intertidal habitats.


Fig 1. This dogwhelk drilled through the shell of this mussel to  begin consuming it. Then, after the mussel relaxed (probably  because it died), the dogwhelk went around to the gaping edge  where it is easier to access the mussel's viscera and inserted  its proboscis to continue feeding, shown here.

Dogwhelks have small ranges and do not disperse gametes or larvae at sea, making them an ideal species to study local adaptation. After copulation, the female glues egg capsules to the substrate, in which her eggs develop (Fig 2). When the eggs hatch, the juveniles crawl away, and make their home in the same habitat (Figs 3 & 4). This life history means there is low gene flow between populations, and many generations are exposed to the same selective pressures. Therefore, populations are extremely likely to evolve differentially.

Fig 2. A dogwhelk (the snail in the middle) with its egg capsules (the yellowish 
ovals around the snail) at Fogarty Creek, Oregon, 17 June 2014. The egg 
capsule contains dozens of eggs, which will develop into baby dogwhelks
that will crawl away and live out their lives in the same rocky area.


Fig 3. A juvenile dogwhelk emerging from 
its egg capsule. The capsule is about
1 mm in diameter.

Fig 4. Emerged juvenile dogwhelks on the side of a cup. The mesh size is 1 mm for reference.



Seawater pH and dogwhelk prey choice vary along the west coast
Intertidal pH sensors placed by the Ocean Margin Ecosystems Group for Acidification Studies (OMEGAS) in Oregon and California show how varied and dynamic seawater pH is along the west coast. This variation could be the source of differential selection pressures in intertidal habitats.

Studies have shown that populations of Nucella dogwhelks of the same species varied in the mussels they consumed, and that prey choice is heritable. Since increased acidity can affect mussel shell thickness, I aim to understand how pH and mussel shell traits may influence dogwhelk prey choice. I also aim to understand if dogwhelks are genetically adapted to local pH or available mussels and the consequences of such local adaptation on the community. This is important because it will be among the first of studies demonstrating the ability of marine species to evolve in pace with climate change, and the effects this rapid evolution can have on communities.

In the next few years, I will examine prey choice of dogwhelk in the field and test whelks from all areas on specific mussel types in seawater of varying pH. This will help me determine if they are locally adapted to mussel types or seawater pH. Then I plan to analyze the dogwhelks' radular morphology (Fig 5) and acid composition to see if there are differences in these important feeding structures.


Fig. 5. A Nucella radula under ~100x magnification. The upper left end is the posterior end, 
which is cut. Not bad for a cell phone camera-through-compound microscope shot!

Eventually, I would love to have help sequencing whelk DNA and examining the chemical composition of whelk acid. Research on the geographic structure of whelk genes or acid in relationship to their feeding ecology could result in at least one publishable scientific paper. I will be collecting these whelks anyway, so if you have any interest in whelk genetics or biochemistry, I would love to collaborate! I am very excited about all of this and am VERY interested in working with other researchers with different specialities. I do not have a background in genetics or biochemistry, so any help there is greatly appreciated.











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Former research system and ideas


If you are interested, this is what I was originally proposing to study.

Here is a conglomeration of keywords where larger words are more important in my research (it's called a wordle).



I am developing a project to examine contemporary trait change in an important harvested fish species, the California sheephead (Semicossyphus pulcher). This long-lived fish lives in kelp forests along the southern California coast south to Baja California, Mexico. Size-selective fisheries have decreased the average size of the sheephead, and smaller sheephead are less effective at eating sea urchins (Strongylocentrotus spp). Since sea urchins are a major kelp herbivore, decreasing sheephead sizes could lead to greater urchin abundance which could lead to lower giant kelp (Macrocystis pyrifera) biomass. Giant kelp is extremely important for habitat since many organisms rely on it for growth and development. My research will examine how fisheries have changed the traits of sheephead across its range and how these trait changes affect urchin and kelp abundances.

Fig 5. A california sheephead (Semicossyphus pulcher) approaching a 
sea urchin. Perhaps the fish will devour the urchin. Perhaps 
the fish will pass up the urchin and continue on its merry way.
Photo credit: Mark Conlin

There are two major types of sheephead fisheries in southern California, and they have different effects on sheephead populations. The commercial fishery targets intermediate-sized sheephead and can take them in very large quantities, while the recreational fishery strongly targets only the largest sheephead, and potentially fewer of them. The result is that populations of sheephead have had different treatments: (a) significant size reduction while density remains relatively normal and (b) significant density reduction while size structure remains relatively normal. My goal is to identify populations with each "treatment" and survey those populations and the associated habitat. I would then determine what effects reducing sheephead sizes and reducing density have separately on sheephead, urchins, and giant kelp. And, thanks to the excellent MPA system in California, there are plenty of populations that are not directly affected by fishing which can serve as control groups (Fig 1).

Eventually, I want to create a model to help policy makers understand the ecosystem effects of the sheephead fishery. In the model you could input values for fishing selectivity and intensity and find out what the ecosystem effect might be. For example, with the model you could answer a question like: If there are only really selective fishers taking all the biggest fish (say, over 2 feet long), how many fish could they take before we start seeing an increase in urchin populations? or How many fish could they take before we start seeing a decrease in giant kelp?



Fig 6. Hypotheses of effects of fishing on the sheephead-urchin-kelp trophic cascade. Sport fishing selectively removes largest fish but leaves many small that feed on very few urchins, greatly reducing kelp biomass (left column). Commercial fishing is highly intense but leaves largest fish that eat urchins, so urchin grazing only somewhat reduces kelp biomass (middle column).  Where both fisheries are present, sheephead body size and density are reduced, resulting in many urchins and no kelp (right column). 


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