ABOUT OUR RESEARCH

We work on a wide variety of projects at the intersection of theoretical, empirical, and applied ecology.

 

As a quantitative ecologist, I have the pleasure of being able to work on a variety of different problems and in collaboration with many wonderful scientists. I am broadly interested in population and community ecology with particular interests in how dynamics at these levels of organization play out in space. My students and I have worked on problems using a mixture of modeling, lab experiments, and field studies. Some of our current projects are described below.

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Temporal stability of river communities in dendritic networks at multiple spatial scales

The overriding goal of this research is to understand how environmental variation, dispersal, and river network structure influence benthic community dynamics. Using a combination of field surveys, experiments, and mechanistic modeling, we are directly testing how network structure alters patterns of dispersal connectivity and stability in river macroinvertebrate communities. This work has been funded by the NSF in collaboration with Bryan Brown, Eric Sokol, and Chris Swan. We are currently extending our efforts to include the effects of demographic and environmental stochasticity in order to project community responses to global change. This more recent work is funded through a new joint NSF/São Paulo Research Foundation program with Bryan BrownVictor Saito, Tadeu Siquera, and Chris Swan.         

Ecological theory for spatial population and community dynamics

A longstanding and continual focus of the lab is developing theory that explores how population and community dynamics play out across space. We work on both "strategic" theory aimed at elucidating general principles as well as "tactical" modeling that guides work in empirically-oriented projects. Current modeling looks at stability properties of spatial food webs on a range of spatial network types, asking how connectivity patterns alter food web structure and dynamics, as well as how these are altered by underlying patterns in environmental variation. We are also examining food web models to explore how trophic interactions influence larger food web stability, with particular focus on omnivory, cannibalism, and trophic polymorphisms.

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Testing the relationship between spatial network structure and food web stability

Spatial ecological networks, such as the spatial distribution of habitat, are often patchy
and irregular. We are combining experiments and mechanistic modeling to directly test how patterns of dispersal network connectivity alter stability in food webs across a range of system productivities. Most of this research is conducted using laboratory microcosms, which allows us to follow metacommunity dynamics over long time scales difficult to achieve in the field. This research was initiated through funding by an NSF CAREER Award and involves extensive collaboration with UCR undergraduate scientists.

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Population and community ecology of alpine freshwater habitats

Global change is driving rapid change in alpine ecosystems. This is especially true in alpine freshwater habitats, which are seeing reductions in glacier and snowfield extents and alteration of precipitation regimes. Alpine freshwater habitats also contain significant biodiversity, making them an increasing focus of conservation concern. We are piloting several projects aimed at understanding how changing environmental gradients influence population dynamics and community patterns in these systems. One particular area of interest is how connections among different types of habitats, such as among lakes, streams, and ponds, alter biodiversity patterns from what would be expected from local abiotic variables alone. Field work has been conducted in the San Jacinto mountain range at the James and Oasis de los Osos Reserves, in the Sierra Nevada range at the Sierra Nevada Aquatic Research Laboratory, and in the Rocky Mountains at the Niwot Ridge LTER.

Ecology and conservation of the Santa Ana river, an urban, effluent-dominated system

The Santa Ana watershed is one of the largest socio-ecological systems in southern California. It contains 23 species of concern, including the federally threatened Santa Ana sucker. It also encompasses >5 million people, 26% of which are disadvantaged. We are examining the causes and consequences of large-scale ecological change in this system, with current focus on quantifying community composition and food web interactions in a reach where wastewater is the major source of flow. Work with Dr. Helen Regan aims to assess freshwater sustainability under climate change by considering the linkages between human water uses, freshwater ecosystems and governance using the Freshwater Health Index.

Innovative Learning Technology Initiative in Ecology, Conservation, and Global Change

We developed online courses in Ecology and Conservation Biology and Global Change Ecology that employ novel instructional technologies to 1) enhance knowledge of ecology and the interaction between natural ecosystems and human populations, and 2) expand access to high quality upper division instruction in ecology, conservation, and global change. Current assessment efforts aim to quantify student attitudes towards online courses and success in meeting learning outcomes. This project has been a collaborative endeavor with Dr. Anne Hilborn, Dr. Loralee Larios, Dr. Paul Nabity, Dr. Nicole Rafferty, Dr. Helen Regan, Dr. Marko Spasojevic, and the staff in the UCR Instructional Design & Faculty Technology Support Group.