Research
Interests
My
research examines the effects of non-native, invasive species
on natural habitats, the
mechanisms
underlying
invasion success, and insect herbivore-mediated interactions between
native and non-native plants. My research objectives include: 1) understanding ‘how’ and ‘why’ some
invasive species (but not others) are so successful, 2) elucidating how
insect herbivores alter competitive interactions between native and non-native
species, 3) identifying host specific natural enemies and testing their
efficacy in controlling invasive species, and 4) examining conservation
and restoration strategies before, during, and after invasive species
control or removal.
Ecological
interactions among native and non-native species
Temperate ecosystems
Northeastern North American forests, fields, and wetlands
are invaded by a diverse exotic flora - lack of coevolved herbivores appears
to be the primary driver of exotic plant success. But, white-tailed deer
populations and their preference for native plants may also have an effect
on native and exotic plant interactions. We are examining the combined
effects of insect and vertebrate herbivores on native and exotic plant
success in this ecoregion.
Aquatic and riparian ecosystems
Another
project focuses on the interactions of native and non-native plants in
riparian
systems in the southwestern United States and documenting how
non-native
plant invasions in riparian areas of this semi-arid region are altering
ecosystems. We are establishing baseline measures of the environmental
effects and changes in biodiversity caused by establishment of non-native Arundo donax and Tamarix spp., evaluating the current
herbivore complex associated with Arundo in the United States,
and studying herbivore effects on Arundo growth and survival.
A similar
project examines
competitive interactions of native and non-native biotypes
of Phragmites australis. The non-native biotype is rapidly invading and
changing wetland ecosystems in the United States and replacing native
biotypes. I
am studying the factors that enable the exotic biotype to out-compete
the native biotype and other native plants, and how biodiversity
changes and
declines over time as the non-native species invades. I am also looking
at the differential susceptibility of the native and non-native biotypes
to
native and non-native herbivores.
Population dynamics and distributions
I am researching genetic structuring among the different Phragmites biotypes
using molecular techniques (RFLP’s and ISSR’s). With this information,
I am constructing a GIS database to map the distribution of native and non-native
biotypes in New England and California. This database, which incorporates
georeferenced data and population parameters (distribution and abundance,
genotype, habitat), will enhance conservation efforts for native biotypes
and control efforts for the non-native biotype. This database will also be
used to study the spread of invasive species and their effects on biodiversity.
Another aim of this research is to develop accurate and ‘easy to use’ genetic
techniques for identifying closely related native and non-native plants.
Tri-trophic interactions
My research often focuses on both pairwise and tri-trophic interactions
between plants and insects to elucidate complex interactions in ecosystems.
For example, one of my projects examines the multilevel relationship
between secondary chemicals and defensive structures in tomatoes, herbivores
that feed on these plants, and their insect predators. I have found that
although plants and insect predators often have mutualistic relationships,
plant defenses can have unintended and detrimental effects on predator
movement and survival. Future research will focus on the relative effects
of plant defenses on generalist insect predators versus specialist insect
predators, which may be adapted to host-specific plant defenses. I am
also interested in how allelochemicals differ among plant genotypes and
how these differences affect plant quality, competitive interactions
among closely related plants, and herbivory.
