My thesis explored the effects of environmental variability on population
dynamics and community composition of aquatic insects. Environmental variability in
the form of flow regime in streams can limit the distribution and life-history traits of
aquatic insects. I used tributaries to the McKenzie River in Oregon with dramatically
different flow...
Glutamine synthetase in the embryonic chick neural retina
shows a 50 fold increase in activity between the 16th and 17th day of
embryonic development. This increase in enzyme activity results
from de novo enzyme synthesis thus making it a useful marker of
differential gene expression. A precocious rise in activity...
The 13 species of shrimps studied for this thesis were collected
off the Oregon coast. The family Oplophoridae is well represented
in this area. Five of the seven known genera were identified.
Hymenodora frontalis, H. glacialis, and H. gracilis were described
and further differentiating characters were illustrated. Other members
of...
Like other species interactions in ecological systems, host-pathogen interactions are influenced by environmental factors, landscape characteristics and the broader community context. My thesis explores the potential influences of food-web interactions (Chapter 2), climate change (Chapter 3), landscape structure and host movement patterns (Chapter 4), and the combined influences of local...
The western Plethodon include vandykei vandykei, v. idahoensis,
larselli, dunni,vehiculum, stormi, elongatus, and an undescribed
form referred to as the "unstriped" Plethodon. These
salamanders have been placed into three species groups: the
Vandykei group, the Vehiculum group, and the Elongatus group.
Range maps are provided and geographic variation is discussed...
Biological invasions provide a unique opportunity to study the mechanisms that regulate community composition and ecosystem function. Invasive species that are also ecosystem engineers can substantially alter physical features in an environment, and this can lead to cascading effects on the biological community. Aquatic-terrestrial interface ecosystems are excellent systems to...
I examined two amphibian communities to assess factors
that may impact amphibian biodiversity. The results suggest
that the potential factors which influence the maintenance
of amphibian biodiversity are multi-faceted and thus,
attempts to understand these factors must reflect these
complexities.
I investigated factors that influenced the susceptibility
of western toad...