I experimentally test the hypothesis that the potential for selfing
increases with plant size in Mertensia ciliata (Boraginaceae), a self-compatible,
profusely-flowering perennial. This follows from the
premises that 1) pollen dispersal by pollinators between flowers is
limited, and 2) individual pollinators, in this study bumblebees, will
visit more flowers per...
In their modern context questions of heredity have come to be
closely aligned with theories of evolution because all such theories
require the presence of heritable variation. Thus the need for an
understanding of a source of variation and a mechanism for its inheritance
became very apparent with the general...
The dynamics of a field population of the cinnabar moth, Tyria
jacobaeae L., were studied near Jordan, Linn County, Oregon. In
both 1970 and 1971 larval populations were so large that all foliage of
the host weed, tansy ragwort, Senecio jacobaea L., was consumed.
The ensuing starvation accounted for the...
Thais emarginata is a gastropod which inhabits the midlittoral
zone of the intertidal region. Oxygen consumption of high-level and
low-level organisms was determined at various seasons of the year
over an experimental temperature range of 5 to 20° C.
No significant difference in respiratory rate between separate
populations of high-level...
During the years between 1930 and 1950 a number of attempts
were made to introduce techniques and ideas from cytology,
ecology, and genetics into the field of taxonomy. Advocates of
this "experimental taxonomy" believed that cytological, ecological,
and genetic techniques would provide a rigorous, objective
methodology to replace the traditional...
Aspects of the life history and ecology of the intertidal turf-forming
alga Rhodomela larix (Turner) C. Agardh were examined over a two
year period at several sites on the Oregon coast. Rhodomela occurred
over a broad tidal range and exhibited different growth and morphology
characteristics with respect to tidal height....
I tested a theoretical model proposing that anemia
favors transmission of blood-borne parasites to vectors
by accelerating the blood-feeding rate. Using Aedes
aegypti, the yellow fever mosquito, initially, I was not
able to confirm this phenomenon either in an artificial
or a live system; anemia did not correlate with blood-feeding...
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...
Identifying appropriate units for conservation requires knowledge of evolutionary
patterns and risks of managing at different geographical and genetic scales. I examined
genetic diversity at different geographical scales among 11,400 rainbow trout
(Oncorhynchus mykiss) from 243 locations in 13 major river basins throughout much of
their range and among coho...
Effects of the marine environment on age and size at maturity, early marine growth, and abundance of chum salmon, Oncorhynchus keta, were studied at Olsen Creek during 1959-77. Chum salmon returned to Olsen Creek as predominately 3-, 4-, and 5-year fish; however, age composition varied from year to year. The...
The effects of burial by tephra (volcanic aerial ejecta) on
forest understory plants were examined northeast of Mount St. Helens,
Washington, in the area where the 18 May 1980 eruption deposited
tephra but did not destroy canopy trees. At six sites along a tephra
depth gradient from 2-15 cm, understory...
Habitat selection behavior was investigated as a proximate mechanism influencing spatial distributions of three species of anuran larvae. Rana cascadae, Hyla regilla, and Bufo boreas overlap in distribution in lakes and ponds of the Cascade Mts. and were chosen to provide a comparative basis for analyzing habitat selection behavior. Major...