Biological studies were conducted on a histozoic myxosporidan
Myxobolus insidiosus (Wyatt and Pratt, 1963) from the musculature of
Oncorhynchus tshawytscha (Walbaum). This organism is known to
occur in spring chinook salmon in Oregon and coho salmon O. kisutch
(Walbaum) in Washington. In addition Myxobolus kisutchi (Yasutake
and Wood, 1957) was...
This report summarizes the results of a field study of a population
of the Pacific mountain beaver, Aplodontia rufa pacifica, from
August 1965 through August 1967. The study site consisted of a 13. 5-
acre grid on a logged over area in the Coast Range Mountains of
Benton County, Oregon....
Organismal tolerance to abiotic environmental stresses contributes significantly to setting the distribution limits of organisms, as demonstrated by vertical zonation patterns in the marine intertidal zone. In this thesis, the ultimate (evolutionary) and proximate (mechanistic) causes of tolerance to temperature and emersion stresses associated with the intertidal zone were examined...
Using techniques that permit the direct observation of
fetuses in vivo, prenatal behavioral development was
compared among four species in the rodent family Muridae:
the Norway rat (Rattus norvegicus), Mongolian gerbil
(Meriones unguiculatus), cotton rat (Sigmodon hispidus), and
spiny mouse (Acomys cahirinus). Rattus and Meriones bear
altricial offspring, as do...
The karyotypes of five species of ranid frogs were determined
from metaphase plates of bone marrow cells. The colchicine, hypotonic-
citrate, blaze-dry technique was used to obtain the plates.
Morphometric datawere obtained from the karyotypes and compared
with other species of the genus Rana.
Like most other members of the...
Analyses of sympatric and allopatric populations of Sceloporus
occidentalis and S. graciosus from central Oregon indicate a high degree
of similarity in diet. Relative abundance, the equivalent number of
equally common taxa (E), and the probability of similarity (SIMI) were
used in the analyses. Shifts in diet between populations of...
Clinocardium nuttallii from Yaquina Bay, Oregon, were found to
harbor an algal symbiont in the siphon, mantle and occasionally
the foot tissues. Approximately 35 percent of the population in the
study area was infected to some degree with the alga; however, no
cockles under two years of age were infected....
A fluke found in the intestine of the red-legged frog, Rana
aurora Baird and Girard, was identified as Brachycoelium lynchi
Ingles 1936. The life cycle of this fluke was studied and found to
be of the lecithodendriid type rather than brachycoeliid. Instead
of having one intermediate host, as is the...
The objective of this study is to assess the quantitative
genetic structure of fitness characters in Tribolium confusum
flour beetles. Estimates of genetic variation and covariation for a
series of fitness components (two measurements of survival,
larval weight, development time, fecundity, and female
productivity) were obtained from two populations of...
With a growing emphasis on details of behavior comes an increasing
need for knowledge of natural behavior patterns. Studies
on the life history of Peromyscus maniculatus have long been available
in the literature. More recently, investigators have turned to
analyzing the behavior of some of the subspecies of P.m. in...
I experimentally examined the adaptive significance of the
anatomical and behavioral convergence between the harrier (Circus
cyaneus, also refered to as the marsh hawk) and certain owls that are
capable of capturing prey in total darkness. Anatomically, both the
harrier and owls have evolved a sound collecting facial ruff (a...
Vertebrates communicate with one another and coordinate intraspecific reproduction by using a variety of sexually dimorphic signals, such as plumage, ornaments, sounds, and/or scents. These sexual dimorphisms are maintained by physiological factors, typically sex-specific hormones (though see Chapter 3 for an exception). The purpose of the research in this dissertation...
The acute phase response (APR) includes an early response of the innate immune
system to an inflammatory agent. Acute phase proteins (APP) are produced at
increased rates in the liver during this response. The APR has been well
characterized in mammals, but it is unclear to what degree teleosts mount...
In this dissertation I study evolutionary patterns at genes encoding antimicrobial peptides (AMPs) in frogs. AMPs are short, amphipathic, cationic, secreted proteins that kill bacteria and other pathogens through a non-catalytic mechanism that involves
binding to and disrupting the microbial cell membrane. In many animal taxa, positive selection is much...
This dissertation focuses on science relevant to the design and implementation of marine reserves. The chapters explore a range of topics related to among-site variation in population, community, and ecosystem dynamics. My results demonstrate the value and feasibility of integrating this knowledge into more comprehensive conservation and management approaches. While...
Gradients of physical disturbance are central to
theories of community organization yet rarely are studies
performed in which physical factors are experimentally
manipulated. Pothole tidepool algal communities exhibit
distinct zonation patterns from top to bottom that result
from scouring by rocks and other debris in the pools.
Scouring is easily...
Emerging infectious diseases are increasing globally and are a threat to human, wildlife, and ecosystem health. The emerging fungal pathogen, Batrachochytrium dendrobatidis (Bd), or amphibian chytrid fungus, is associated with worldwide amphibian population declines and extinctions. Bd has been found on every continent where amphibians exist and has been documented...
The ecology of a population of snowshoe hares, Lepus
americanus washingtonii, was studied in western Oregon from 1960
to 1962. Objectives were to obtain information to control hares,
which frequently cause damage to coniferous reproduction in the
region, and to compare the life history of this little-studied subspecies
with others....
The purpose of this study was to record on tape and to
analyze the sonagrams of the complete repertoire of the vocalizations of the Rufous-sided Towhee, Pipilo erythrophthalmus
oregonus. Meanings were assigned to a number of the calls.
Sounds of nestlings, juveniles, and vocalizations connected with
parental care were not...
The distribution and abundance of the interstitial acoel turbellarian,
Diatomovora amoena Kozloff, 1965 was studied in an
estuarine intertidal sand flat in Yaquina Bay, Oregon, from May
1970 through May 1971.
Monthly measurements of biological (organics, sulfides, chlorophyll,
and carotenoids), pore water (salinity, pH,oxygen, and temperature),
and sediment (fine sediment...
Albumin, as a percent of total proteins in both the coelomic
serum and the blood serum, was determined for four groups of
developing Rana catesbeiana tadpoles by cellulose acetate electrophoresis.
Also, using Folin phenol reagent, the total protein of
each the blood serum of metamorphosing tadpoles and the coelomic
serum...
Climate change is predicted to affect ecosystems, including systems already stressed by human impacts. One ecosystem that is already highly impacted by human land use is the cold headwater stream system of the Pacific Northwest. One method of assessing the function of an ecosystem is by using an indicator species....
Oogenesis in the sea urchin Strongylocentrotus purpuratus was
studied at the fine structural level, with special emphasis on the relationship
between the two main cell types within the ovary: the egg cells
and the nutritive phagocytes, or accessory cells. The nutritive
phagocytes are flagellated cells with extensive pseudopods which store...
Although it is generally assumed that the intensifying abiotic environment is the primary effect of drought on aquatic organisms, drought-induced top predator extinctions may be an important underlying mechanism. I used manipulative experiments to disentangle the impacts of drying and top predator extinctions on arid-land aquatic invertebrate communities. I then...
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...
Although only a minority of introduced species become established and have noticeable consequences in their new communities, some can displace native species, alter food webs, and cause local extinctions. Studying these invasive species can provide new insights into basic ecological questions as well as inform management strategies. Pacific lionfish (Pterois...
The organization of behavioral activities in time is important
to a bird's survival and reproduction. To be successful, either
proximately or ultimately, a bird must apportion its behavior in time
so that it may obtain sufficient energy for maintenance activities and
for such activities as migration and reproduction. The organization...
The energy strategies of early development of the Pacific Oyster,
Crassostrea gigas, were examined. Changes in proteins, total carbohydrates,
free reducing sugars and total and neutral lipids were
determined for the unfertilized egg and larval stages through 13 days
post-settlement.
During early larval stages neutral lipid levels decreased and
provided...
Careful analysis and thoughtful synthesis will be necessary for expanding the envelope of
ecological understanding. This work is my attempt at communicating both of these, in relation
to three questions about our understanding of the structure and dynamics of biological diversity.
These questions focus on a) advancing our understanding of...
Of 2,122 marine fishes belonging to 36 species collected in the
vicinity of Newport, Oregon, 541 belonging to 8 species were infected
with hemoflagellates. Four species of trypanosomes and three species
of cryptobias were found in offshore fishes, but no hemoflagellates
were observed in fishes from Yaquina Bay.
Trypanosoma pacifica...
The relationship between nutrients and community structure is poorly understood in open-coast habitats. I created a system of artificial tidepools, of identical age and physical dimensions, at two sites that differed in wave exposure, and manipulated nutrient levels and the abundance of herbivores. Using these unique field mesocosms, I explored...
The breeding habits and embryonic thermal requirements of the
Cascade frog of Oregon, Rana cascadae Slater, are described. The
limits of temperature tolerance of the pre-feeding stages are from
6° to 27°C for embryos held at constant temperatures. However, for
pre-feeding embryos exposed at different developmental stages for
short durations...
Most climate change predictions focus on the response of individual species to changing local conditions and ignore species interactions, largely due to the lack of a sound theoretical foundation for how interactions are expected to change with climate and how to incorporate them into climate change models. Much of the...
This study was initiated to determine the concentration
of magnesium and calcium in dividing eggs of the sea
urchin Stroncavocentrotus purpuratus and to explore the
relationship between these ions and mitotic events.
Samples of developing eggs, maintained at 15°C, were
taken at ten-minute intervals from fertilization through
the second cleavage,...
Calcium concentration and its regulation was examined in
tissues of larval Rana catesbiana. Considerable variability was
found in tissue calcium that could not be explained by stage of development.
A seasonal effect was observed, with plasma calcium decreasing
and muscle calcium increasing during winter. Total plasma
calcium concentration reflects, within...
Diet variation among individuals within populations is widespread. Often diet differences among individuals are attributable to obvious differences among individuals such as age, sex, or morphology. However, growing evidence suggests that individual diet variation is also common among seemingly identical individuals within populations. This phenomenon has been termed individual diet...
Predator-prey interactions have historically been studied to explain patterns of organization observed in populations and communities. They have also been important in understanding the evolution of antipredator responses in prey and counterstrategies in predators. Despite the breadth of knowledge that exists for heterospecific interactions, relatively few studies have investigated the...
The radiorespirometric method was used to study the catabolism
of glucose in intermolt crayfish. Rapid and extensive conversion
of C-3(4) of glucose to C¹⁴O₂ indicated that a significant
portion of the administered glucose was routed into the glycolysis-
Krebs cycle sequence. High yields of C-6 of glucose in the respiratory...
Intracellular symbioses between cnidarians and dinoflagellates from the genus Symbiodinium are widespread throughout the marine environment. These associations are ecologically significant, especially in tropical waters where symbiotic interactions between corals and Symbiodinium culminate in the formation of limestone reefs. This thesis focuses on cellular and molecular aspects of the symbiosis,...
The multifaceted role of the environment in regulating the structure and dynamics of biological communities has long fascinated ecologists and motivated much debate and research. Now, in a time of accelerated global changes due to human impacts, the need to understand how the environment shapes communities has gained new urgency....
Because arginine vasotocin (AVT) activates male sexual behaviors in the rough-skinned newt (Taricha granulosa), quantitative autoradiography with radiolabelled arginine vasopressin (³H-AVP) was used to localize and characterize putative AVT receptors in the brain of this amphibian. Binding of ³H-AVP to sites within the medial pallium was saturable, specific, reversible, of...
Chemoreception is one of the dominant sensory modalities for many species of salamanders (reviewed in Chapter 2). At least seven of the ten currently recognized salamander families are known to respond to some sort of chemical cue. These responses are as varied as delaying hatching, seeking refuge, or initiating aggressive...
My dissertation focuses on the evolutionary forces that have shaped the chemical signaling system of plethodontid salamanders. Pheromones mediate two phases of plethodontid reproduction: mate attraction prior to courtship and female persuasion during courtship. Substrate-borne chemical signals are believed to play an important role in mate attraction for these animals....
Developmental changes in the enzymes acetylcholinesterase
(EC 3.1.1.7) and pseudocholinesterase (EC 3.1.1.8) were
examined in ovo and in vitro in the neural retina of the
developing chick. In addition, investigations of cellular
interactions and hormones as possible control mechanisms of
enzyme synthesis were made.
The specific activity of acetylcholinesterase, a...
Most vertebrates exhibit seasonality in many life history traits. Such seasonal rhythms are temporally organized via the transduction of environmental cues (e.g., photoperiod, temperature) into appropriate endocrine signals. However, among ectothermic vertebrates that undergo continuous winter dormancy, temperature is the only environmental cue available for synchronizing seasonal rhythms. Most intriguing...
Biological invasions and climate change represent two preeminent threats to ecological communities and biodiversity, altering the distribution and abundance of species, disrupting existing species interactions and forming unprecedented ones, and creating novel ecological communities. Many of the most successful invasive species are also ecosystem engineers, species that physically modify the...
Succession and organization of rocky intertidal zone surfgrass beds
(Phyllospadix scouleri Hook) were examined experimentally at two sites
on the Oregon coast. The interaction of three attributes of the plant
-- high persistence, high preemption, and slow recovery -- strongly
influences the organization of surfgrass beds. Permanent plots indicate
that...
Chromosome maps were made of Drosophila gibberosa salivary gland
and fat body chromosomes, and the puffing patterns were compared in
the two tissues for selected times in development. The times were
early third instar (E), late third instar (0, at pupariation
(0 hr), at two hours (2 hr), four hours...
In the rat thymus, four stages of development have been distinguished:
(1) a newborn stage (Stage I), (2) an accelerated growth
stage (Stage II), (3) an involuting stage (Stage III), and (4) an involuted
stage (Stage IV) . There were three major types of thymic
lymphoid cells: small (STL), medium...
Emerging infectious diseases impact both human and wildlife populations. Infectious agents, in particular the aquatic fungus Batrachochytrium dendrobatidis (chytrid), have an influential role in driving global amphibian population declines. The emergence of the chytrid fungus has aspects of both geographic spread as well as climate shifts altering environmental conditions and...
Whether microevolutionary processes can explain macroevolutionary patterns has long been a matter of contentious debate. The debate has persisted largely because of the challenging task of connecting microevolutionary theory, which examines population-level phenomena on the generation scale, to data collected across larger spatial and temporal scales. My dissertation research broadly...
Because many coral-reef fishes are observable in situ, are amenable to transplantation, have small home ranges and short generation times, they provide a excellent system to investigate many topics within general ecology, fisheries biology, and conservation biology. The primary goal of this dissertation was to use the coral-reef fishes system...
This thesis describes studies that investigated 1)
the effects of courtship on the neuroendocrine system of
female rough-skinned newts, Taricha granulosa, and 2)
whether the observed courtship-induced neuroendocrine
changes affected female sexual receptivity.
Sexual behaviors of female T. granulosa changed
dramatically during courtship. Initially, females
exhibited unreceptive behaviors to a...
Cardicola alseae is a blood dwelling trematode found in the
fishes Salmo clarki henshawi and Salmo gairdneri gairdneri. Eggs
which were ovoid in shape and non-operculate left the adult and passed
to the gill capillaries of the secondary lamellae. The miracidium was
ovoid, 0.070 mm. long by 0.052 mm. wide,...
Developmental series of Rana pretiosa (110 specimens), R.
cascadae (100 specimens) and R. aurora (115 specimens) were bone
stained and cleared in glycerin. The growth and developmental patterns
of the skull and selected bones were followed from the first
appearance of bone through adult stages. The sequential appearance
of the...
The Tailed Frog Ascaphus truei, the only species in the
family Ascaphidae found outside New Zealand, is a common inhabitant
of the mountain streams of the Northwestern United States and
British Columbia. The anatomical peculiarities of this primitive
anuran have been investigated, but no literature is available on the
digenetic...
Accurate chromosome segregation and cell cleavage are critical to maintaining genomic integrity. Both events involve the spindle apparatus, but the exact mechanics is as puzzling as the contradicting models proposed in the last two centuries. In this dissertation, current prevailing models of chromosome segregation and cell cleavage are tested using...
Low intertidal communities of Oregon and Panama have many predator
and herbivore species. This diversity of consumers is important to the
organization of both communities because of qualitative differences
among the consumer species in their ability to circumvent specific prey
defenses. In Oregon, the red alga Iridaea cordata is protected...
The size, shape, and stability of a species’ dietary niche can both influence and reflect a variety of biological patterns, including species interactions, extinction risk, and ecosystem function. This is particularly apparent when dietary changes manifest at ecosystem and clade scales to profoundly affect macroecological and macroevolutionary trajectories. However, many...
Understanding the mechanisms that regulate local species diversity and community structure is a perennial goal of ecology. Local community structure can be viewed as the result of numerous local and regional processes; these processes act as filters that reduce the regional species pool down to the observed local community. In...
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...
To assess the context dependence of kin discriminating
behavior, I examined kin-biased aggregation behavior in tadpoles
of R. cascadae in different ecological conditions. I manipulated food
distribution, predator presence, thermal heterogeneity, and
relatedness in a multifactorial mesocosm experiment. All four
factors interacted to influence tadpole dispersion. My results
suggest that...
The avifaunal composition of ten western Oregon forest stands located at the eastern base of the Coast Range was examined on a seasonal basis. The stands were dominated by Oregon white oak, Douglas fir or western hemlock, Avian populations were sampled monthly from January 1968 to January 1970, using permanent...
Floods are major disturbance events for riverine ecosystems, directly and indirectly impacting organisms and their habitat. In this study I investigated the role of riverine floods and flow alteration in regulating aquatic macroinvertebrate population and community structure. I examined this problem using a variety of methods: a meta-analytic review of...
This dissertation focuses on the importance of pelagic subsidies in the Northeast Pacific to rocky shore community regulation. My results document the patterns of pelagic subsidy supply, determine if those subsidies are correlated with community structure, and examine if community regulation differs between areas of high- and low-subsidies. Understanding how...
Along the central and southern Oregon coast and on San Juan Island, Washington, the lined chiton Tonicella lineata is very abundant in the lower intertidal levels on rocky shores. It is usually found on
encrusting coralline algae which, with epiphytic diatoms, make up the major portion of its diet. On...
This dissertation investigates the context-dependency of species interactions between seagrass and macroalgae in upwelling-influenced estuaries. In all coastal systems, nutrient loading is multidirectional, resulting from mostly freshwater and marine inputs. The directionality of nutrient inputs may affect the rate of supply of organic matter to the system. In systems where...
Oxygen binding behavior and subunit association-dissociation of
the hemocyanin from Callianassa are sensitive to several environmental
variables. Callianassa californiensis is a burrowing estuarine which
must survive changes in salinity, temperature and oxygen availability.
Previous work on the structure and function of the hemocyanin was
done under conditions which did not...
Environmental stress can negatively affect the ability of organisms to reproduce. Energetic trade-offs exist in all organisms, and under stress, energy may be allocated away from reproduction and towards physiological defense and repair mechanisms. The rocky intertidal environment is ideal for investigating the influence of environmental stress, as organisms are...
The body size (W) of animal species is one of the best predictors of
population density (D) when large assemblages are considered. It has been
shown that theoretically the D-W relationship can be the consequence of two
other distributions: the log-normal distribution of body sizes of the species and
of...
There is increasing awareness that human activities are altering the ways that natural systems operate and that local shifts in species composition and abundance can lead to abrupt and irreversible global change. Therefore, understanding the processes that buffer biological communities from critical shifts and how our actions affect natural stabilizing...
Predatory lionfishes (Pterois volitans and P. miles) were introduced to Florida waters during the mid to late 1980s, and eventually established self-sustaining breeding populations in the tropical western Atlantic. These invasive species are now widespread along the southeastern seaboard of the United States, across the Caribbean Sea, and in the...
Previous attempts to understand the factors affecting the energetic cost of locomotion have found a direct link between the energetic cost and the mechanical work done during periods when the limb is in contact with the ground. However, when the limb is not in contact with the ground during the...
Factors affecting the persistence of mussels (Mytilus californianus) and their associated epibiont species were studied along the central Oregon coast. Interactions between mussels and their algal epibionts (Endocladia
muricata) varied in sign and strength with environmental conditions. In extreme temperatures mussel—epibiont interactions determined survival of individual mussels,
and persistence of...
The causes of the global biodiversity crisis are varied and complex. Anthropogenic threats may act in isolation, or interact additively or synergistically with each other or with natural stressors to affect sensitive taxa. The recent emergence of many infectious diseases in wildlife has brought attention to the role of disease...