Metacommunities in
the pitcher plant, Sarracenia purpurea
In the last 15 years, ecologists
have recognized that population and community patterns are determined
by both the local species interactions, as well as larger patterns
of migration and extinction occuring across larger heterogeneous
regions. This work was built on earlier ideas about patch dynamics
and migration, and has recently led to newer theory and experiments
brought together under a loose theory of "metacommunities."
We have been testing a number of
recent theories about community patterns across metacommunities,
as well as developing some theory of our own. This work has taken
advantage of the unique natural microcosms found in the water-filled
leaves of the purple pitcher plant, Sarracenia purpurea.
This leaves of this carnivorous plant attract insects that drown
in leaves, ultimately providing nutrients for the plant. However,
these prey insects also serve as the basis for a community in
the leaves. Bacteria break down the insects, while serving as
a resource for protozoa, rotifers, and mites. These bacteriovores
are in turn consumed by the larvae of a specialist mosquito, Wyeomyia
smithii.
Our
current work in this system has been in two areas, both supported
through grants from the National Science Foundation. First, we
are testing earlier theory we published on how the importance
of migration in metacommunities depends on the heterogeneity among
local communities with a large region. We have just completed
a series of experiments in which we manipulated both the migration
rates and the among-leaf heterogeneity; much of the spring of
2008 will be spent analyzing these data.
Second, we are very interested in
the evolutionary processes that occur with this community, especially
as they relate to species diversity. These communities provide
a natural system in which to follow the evolution of competing
species. The evolution of competitors has been of long-standing
interest in ecology and evolutionary biology; this interest has
again come to the forefront due to questions about evolution of
niche-partitioning vs. equivalence and nuetral theory.
Long-term Vegetation
Dynamics on a Local Barrier Island, St. George
Barrier island provide very
harsh environments for plants, as they are highly disturbed with
soils that are often saline, nutrient poor, and subject to extremes
in water availability. These habitats are quite important for
ecological and economic reasons. They support a number of unique
plant species, while serving as breeding areas for a number of
birds and marine organisms. Barrier islands also serve as important
buffers that protect more inland areas from both normal wave-action
and storms. Finally, they are also serve as a coastal "canary
in the mine" for observing and understanding the effects
of global climate change related to storms and sea-level rise.
We
are involved in two projects on St. George Island, appoximately
60 miles SW of Tallahassee. First, we initiated a long-term
study of the vegetation dynamics on the island in 1998. An
annual census is conducted each fall, along with other studies
to periodically monitor dune dynamics and characteristics. Second,
we are now using this long-term database to inform dune restoration.
We have identified 6 six species that appear to either withstand
storms or grow back quickly after storms. With funding from the
U.S. Fish and Wildlife service, we are now initiating small restoration
projects on St. George to test the efficacy of these species for
restoration and conservation.
If are interested in further
information about either of these topics, please contact
T. Miller. We are happy to speak to local groups or to work
with K-12 classes on ecology concepts related to either project.