Graduate Student in Population Biology
University of California - Davis
Bodega Marine Lab
rjbest[a]ucdavis.edu

Research Interests

I am interested in the ecological and evolutionary processes that limit the number of species we find coexisting in a particular community. I am working on this long standing question in a group of important marine herbivores - amphipods and isopods (small crustaceans). In bays and estuaries worldwide, these mesograzers consume algae and detritus and increase available light for photosynthesis by seagrasses, which in turn provide habitat for fish and larger crustaceans. Although they are charismatic and (in our region) fun to identify (thanks to John Chapman's chapter in The Light and Smith Manual 2007), we still know relatively little about species-specific differences in feeding habits and physiological tolerances.

How do trait similarities and differences constrain communities?

For species to exist in the same place, they often need to have similar habitat requirements but different resource use or feeding strategies. In Bodega Bay, CA, I am collecting species-specific trait data and surveys of community composition throughout bay habitats (eelgrass beds, mudflats, fouling communities) to understand the relative importance of habitat filtering vs. niche partitioning in structuring amphipod communities.

Caprella californica -->

What are the evolutionary constraints on traits determining community assembly?

If species must evolve differences in some traits (e.g., mouthparts for chewing different kinds of food) and similarities in other traits (e.g., temperature requirements), understanding the relative lability of these traits is an important component of understanding the evolutionary supply of regional and local species diversity. I am delving into molecular phylogenetics with some northern California amphipods to understand how phylogenetic relatedness predicts trait combinations.

Ampithoe lacertosa -->

What trait combinations permit additional species to enter the bay-level species pool?

In Bodega Bay, a few species of amphipods are introduced from Asia or the North Atlantic. In bays with more shipping, introduced species now make up a much larger proportion of the community. To understand what this means for the health of eelgrass ecosystems, I am testing whether the introduced species succeed by having different feeding strategies than the native species, or by simply being physiologically suited to environmental conditions in the bays where they are found.

Bodega Bay (~ 60 miles N of San Francisco Bay) -->

Publications

Best, R.J., and P. Arcese. 2009. Exotic herbivores directly facilitate the exotic grasses they graze: mechanisms for an unexpected positive feedback between invaders. Oecologia 159:139-150.

Stachowicz, J.J., R.J. Best, M.E.S. Bracken, and M.H. Graham. 2008. Complementarity in marine biodiversity manipulations: reconciling divergent evidence from field and mesocosm experiments. PNAS 105:18842-18847.

Best, R.J. 2008. Exotic grasses and nutrient deposition by an exotic herbivore combine to reduce the relative abundance of native forbs. Oecologia 158:319-327.

Links

• I did my MSc research on a positive feedback loop between introduced geese and grasses in the Gulf Islands National Park Reserve of southwest BC, working with Peter Arcese at the Centre for Applied Conservation Research (UBC).

• I am very thankful for support from: