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A genecological approach was used to explore genetic variation for survival in Artemisia tridentata (big sagebrush). Artemisia tridentata is a widespread and foundational shrub species in western North America. This species has become extremely fragmented, to the detriment of dependent wildlife, and efforts to restore it are now a land manage-ment priority. Common- garden experiments were established at three sites with seed-lings from 55 source- populations. Populations included each of the three predominant subspecies, and cytotype variations. Survival was monitored for 5 years to assess dif-ferences in survival between gardens and populations. We found evidence of adap-tive genetic variation for survival. Survival...
The data set contains the results of experimental challenge of captive zebra finches with an American crow isolate of West Nile virus (WNV). Data include infectivity, mortality, viremia, oral shedding of virus, and serology for anti- WNV antibodies. Australian and Timor zebra finches were used in this study and both are useful as a laboratory model of an avian species with moderate susceptibility to WNV.
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Conclusions: Habitat changes resulting from timber harvest have altered the predator–prey balance leading to asymmetric predation affecting the survivial rates of endangered mountain caribou Thresholds/Learnings: As young forest stands increase in proportion to old forests, caribou population densities and survival rates decline as they become increasingly vulnerable to predation and extripation. Synopsis: Timber harvesting in areas of Mountain Caribou habitat have created landscapes of early seral forests. Such habitat changes have altered the predator–prey balance resulting in asymmetric predation in which predators are maintained by alternative prey (i.e. apparent competition). This study estimates survival...
This investigation evaluated effects of exposure of larval razorback sucker to waterborne and dietary selenium and other contaminants that occur in nursery habitats. Site waters were collected from three localities on the Colorado River near Grand Junction, CO; a total of five test waters (including control) were studied. Razorback sucker larvae were exposed to site-water contaminants via waterborne and dietary exposure using a laboratory food chain (algae, rotifer, razorback sucker). Fish were exposed for 28 days to site waters and food organisms cultured in site waters. Survival data were analyzed by inspection. Growth data were analyzed using analysis of variance to describe the response of fish in each site...
Juniper species are noted for long-lived foliage, low and persistent gas exchange activity and drought tolerance. Because leaves and roots of the same species are thought to be similar in structure and life history, we hypothesized that Juniperus osteosperma (Torr.) Little (Utah juniper) fine roots would reflect the persistent aboveground foliage characteristic of this species. We monitored fine roots, less than 1 mm in diameter, by minirhizotron imaging to a depth of 150 cm over two growing seasons from April 2002 to December 2003. We measured fine root numbers, lengths and diameters, and noted the time of birth and death of root segments. We correlated our root data with soil water potential measured by thermocouple...


    map background search result map search result map Root turnover and relocation in the soil profile in response to seasonal soil water variation in a natural stand of Utah juniper (Juniperus osteosperma). Changes in landscape composition influence the decline of a threatened woodland caribou population Changes in landscape composition influence the decline of a threatened woodland caribou population