Biology Section

Ecology, Behavior & Evolution: Research Topics


The study of the relationships between organisms and their environments.


Biodiversity is a measure of the number of different species that inhabit the thin and fragile layer of atmosphere, ocean and land on the surface of the Earth where life is possible. There are between ten and a hundred million species of animal and plant on our planet, along with a large but unknown number of bacteria and bacteria-like organisms. Only a small fraction of these species have been described, and only a tiny fraction of these in turn have been studied in depth. In UCSD's EBE section we are exploring essential questions about biodiversity: (1) How important is biodiversity to the health and survival of our planet's ecosystems? (2) What are the forces that maintain biodiversity? (3) If biodiversity is lost, how will this harm the survival of our own species?

Biological Invasions

The introduction of species into new environments increasingly threatens the integrity of the earth’s ecosystems. Although such introduction occurs naturally during colonization events, the intentional and accidental transport of species by humans has greatly accelerated the rate at which this process occurs. In most cases introductions either quickly fail or establish with little noticeable effect. A troublesome few, however, establish, spread and profoundly disrupt the environment. Invaders consume, parasitize and compete with natives, and in doing so can alter patterns of species composition and compromise ecosystem services. In some circumstances, especially those involving island systems, introductions even result in the extinction of native species. Invasions often interact with other aspects of human-caused modification of the biosphere (e.g., climate change, habitat destruction and fragmentation, human co-option of primary productivity). Moreover, the unprecedented number of introductions that have occurred over the past century will continue to influence the future evolutionary trajectory of numerous species in unforeseen ways. Given the scope of environmental destruction caused by species introductions, not to mention the immense economic cost of detection, management and control, invasion biology has become an important facet of scientific inquiry.

Research on biological invasions in the EBE section includes the following topics:

  1. What factors control the susceptibility of ecosystems to invasion?
  2. How do introduced species alter trophic interactions and food web structure?
  3. What is the role of phenology (or timing) in structuring native and invasive plant communities?

Trophic Interactions, Food Webs & Communication Structures

Trophic interactions are the foraging relationships among predators, grazers, and plants within a particular food web. Ecologists study the connectedness of food webs and impacts of foraging because these interactions can shape the structure and function of an ecosystem, and identifying these connections allows us to better understand how natural communities work. For example, a predator will directly decrease its herbivorous prey which in turn can have a cascading indirect effect on plant communities as fewer grazers lead to greater plant abundance. The interactions between these three trophic levels serve to shape the structure and function of the plant community. Other species, such as insects, that rely on the plants will also be impacted by any ecosystem changes. Invasive animal or plant species can introduce predation or grazing changes that can perturb the food web and alter the community structure. By studying these foraging connections and their impacts, ecologists can begin to describe some of the mechanisms that shape ecosystems.


Sustainability and Conservation

EBE Professor Michael Soulé introduced the term Conservation Biology here in 1978 and he went on to found a society, a journal and an exciting field. San Diego County has more listed species than any other county and the region saw the first population viability analyses and multiple species conservation plans. Faculty interests are diverse and focus on different aspects of sustaining biodiversity and ecological services at a time of global habitat alteration and species endangerment, and rapid climate change. Recent opportunities for research involved conservation genetics, invasive species, ecosystem simplification, ecology of small and fragmented populations, responses of species to climate change, community restoration, and community-based conservation. Students work both locally and around the world and in terrestrial, freshwater and marine situations. Other local resources of interest to students include the Center for Marine Biodiversity and Conservation, the Sustainability Solutions Institute, and the Center for Research & Training in Anthropogeny all at UC San Diego, and the Institute for Conservation Research at the San Diego Zoo's Safari Park and Hubbs Sea World Research Institute. Interested students should contact individual faculty to establish what projects are currently funded or fundable.