Meiotic chromosome counts from 200 populations of Claytonia
(Montia) perfoliata (sensu lato) reveal a polyploid pillar complex based
on three morphologically different, chemically distinct, and geographically
defined diploids. The basic chromosome number is x=6.
Diploid C. perfoliata Willdenow with linear juvenile leaves and deltoid
mature basal leaves ranges southeastward from...
Claytonia perfoliata is a west-American polyploid complex of
common annuals (x=6). The species is polymorphic; exomorphic
characters are often variable within local populations. In a transect
of the Columbia River Gorge diploids, tetraploids, hexaploids, octoploids,
and decaploids were collected, which varied in shape of basal
and cauline leaves, degree of...
Native lamprey species in the Central Valley of California serve important ecological roles in rivers and tributaries and face similar conservation challenges as salmonids. Concerns of declining lamprey populations have led to collaboration of tribes, local, state, and federal agencies to increase understanding of ecology and life history. Pacific Lamprey...
Expansion of Juniperus occidentalis into the sagebrush steppe has resulted in significant changes in understory composition. A consequence of increased J. occidentalis dominance may be a depletion of the seed bank. The potential for depletion is problematic because a reduction in the amount of species available from the seed bank...
Fifteen species of Noctuidae (Lepidoptera) were collected in alfalfa and
peppermint in western Oregon. Seven of these species were hosts for the braconid
parasitoid Meteorus communis. The most frequently parasitized (percent) species were
Agrotis ipsilon (35.3), Dargida procincta (15.0), and Peridroma saucia (6.9). Other
species parasitized were Autographa californica (3.8)...
The field of conservation genetics, when properly implemented, is a constant juggling act integrating molecular genetics, ecology, and demography with applied aspects concerning managing declining species or implementing conservation laws and policies. This young field has grown substantially since the 1980s following the development of polymerase chain reaction and now...
In the upper estuary of Yaquina Bay, Oregon, there is an annual
population explosion of Acartia tonsa, (Dana) a calanoid copepod,
during the months of July, August and September, followed by a rapid
decline to virtual extinction in November. The restricted estuarine
distribution affords an excellent opportunity to study the...
This dissertation has two objectives. The first objective is to determine where best to situate the study of mentoring (i.e. the 'making of scientists') on the landscape of the history of science and science studies. This task is accomplished by establishing mentoring studies as a link between the robust body...