Oral Presentations: UC 327
|Friday, April 15th|
Non-structural carbohydrates influence water relations in Pinus ponderosa
Aurora Lela H. Bayless
9:00 AM - 9:20 AM
Worldwide forest mortality events associated with climate change are of increasing concern and could have profound consequences on global carbon cycles. There is an increasing need to assess the risk of forest mortality due to climate change. However, model predictions of how forests will respond to drought require specific knowledge of the physiological mechanisms underlying drought-induced mortality. Two main physiological mechanisms have been proposed to explain tree mortality under drought. First, hydraulic failure occurs when the water column in the xylem (vascular tissue) becomes under excessive tension and breaks, thus interrupting water transport. Second, Carbon starvation occurs when plants prevent excessive water loss by closing stomata (tiny pores on leaves), a strategy that also limits photosynthesis (carbohydrate supply) and depletes stored non-structural carbohydrates (NSC). Increasing evidence suggests that hydraulic failure and carbon starvation are intimately interdependent and that plant hydraulic function depends on stored NSC. If so, plants must maintain NSC reserves above certain thresholds to maintain hydraulic function and survive. I conducted an experiment to test whether ponderosa pine (Pinus ponderosa) seedlings require minimum NSC thresholds to survive and whether these thresholds change with drought. Initially NSCs were artificially lowered with one to six week increments of shade. For each dark treatment plants were then brought back to light and divided into two groups, well-watered and drought stressed. Survival and health were monitored. The strongest decrease in NSC occurred in the first week. Preliminary results indicate that mortality of well-watered and drought stressed plants occurred when whole plant NSC decreased to below 40% of that in control plants. Plants who had higher NSC concentrations tended to take longer to die under drought. These data suggest that plants must keep their stored NSC above certain thresholds to survive under drought.
Phenotypic Plasticity & Sexual Dimorphism of the Squinting Brown-Bush Butterfly (Bicyclus anynana)
9:20 AM - 9:40 AM
In many butterfly species, males and females often differ in striking ways. Sexual dimorphism in body size and shape, coloration, behavior, physiology, and life history traits evolve when natural selection or sexual selection acts differently on males and females. The Squinting Brown-Bush butterfly (Bicyclus anynana) is one such example with females larger than males. Additionally, this species is phenotypically plastic - the temperature experienced during larval development will determine the adult phenotype. During the warm, wet, season, these males and females are short-lived, colorful, and active. During the cool, dry, season both sexes are long-lived, cryptically-colored, and inactive. Regardless of the season, the females are always larger than the males. The mating system differs dramatically between the two seasons: in the wet season, males actively court females and females are choosy; in the dry season, females actively court males and males are choosy. Here, we examine the extent of, and differences in, sexual dimorphism of wing size and shape between seasons. Two laboratory populations of B. anynana, originally from Malawi, were reared in 18°C and 27°C, typical temperatures of the two seasonal environments. Approximately 800 eggs were reared at each temperature through adult emergence, for a total of about 400 adult males and 400 adult females. I conducted a geometric morphometric analysis of the wings by identifying homologous landmarks on the forewings and hindwings based on vein-vein intersections, vein-margin junctions and color pattern landmarks. With these data, we are exploring the differences in wing size and shape between the sexes across different temperatures to better understand the relationship between sexual dimorphism and the forms of natural and sexual selection shaping female and male life history and behavior within each seasonal environment.
Effects of conifer removal treatments on quaking aspen regeneration and adult growth
Philip W. Williams, University of Montana, Missoula
9:40 AM - 10:00 AM
Many quaking aspen (Populus tremuloides) populations are in decline across the western United States, a trend likely driven by ongoing climate change and past management that has led to increased competition with conifers. Restoration of aspen is a management goal potentially achievable through active forest management, but treatment effects on regeneration and residual growth have not been comprehensively studied. This project examined if removal of competing conifers altered aspen regeneration density, ungulate browsing, and residual adult aspen diameter growth using a control-impact study design. Sampling occurred at the Burnt Fork (ten treatments, four controls) and Bandy (seven treatments, four controls) sites. Nested plot-centric circles with a common center point were used for sampling. Regeneration was counted in 0.004-hectare plots and examined for ungulate browsing. Adult trees were surveyed in 0.04-hectare plots; diameters and increment cores were taken on the most vigorous tree to represent growth before and after harvest. Ungulate browsing (percent of regeneration browsed) means were higher in treated units (23% and 46% browsed at the Burnt Fork and Bandy, respectively) than in control units (3% and 2% browsed at Burnt Fork and Bandy, respectively). Aspen regeneration was higher in treated units than controls: regeneration at the Burnt Fork site averaged 10743 stems/ha in treated units and 7054 stems/ha in controls, while the Bandy site averaged 13438 stems/ha in the treated units and 6824 stems/ha in controls. Average adult aspen diameter growth rates were stable or increased from pre- to post-treatment in treated units, while diameter growth rates were stable or decreased from pre- to post-treatment in controls. This study demonstrates that silvicultural treatments to remove competing conifer trees can increase aspen regeneration density and maintain or increase adult aspen growth rates. Managers seeking to regenerate declining aspen stands can use conifer removal treatments to promote aspen regeneration.
Comparing changes in fuel loading, tree regeneration, and forest structure in once- and twice-burned mixed-conifer forests
Wyatt Trull, University of Montana, Missoula
10:00 AM - 10:20 AM
Wildfires drive landscape character in the seasonally dry mixed-conifer forests of western North America. Forested landscapes in this region are a mosaic of overlapping burn perimeters which span a wide gradient of severity and burn age. The goal of this study was to compare the effects of single and repeat wildfires on fuel loading, tree regeneration, and forest structure. Our study site spans the east and west sides of the South Fork of Flathead River in the Bob Marshall Wilderness. Data was collected in 2011, eight years after the initial fire burned both sides of the river. In 2013, the east side of the river burned a second time and in 2015, plots on both the east and west side of the river were resampled. Between 2011 and 2015, mean coarse woody debris load (>7.6 cm diameter) in twice-burned plots decreased by 23%, while once-burned plots increased by 76%. Fine woody debris (<7.6 cm diameter) increased by 12% in twice-burned plots and increased by 184% in once-burned plots. These changes in woody debris are the net outcome of inputs from standing dead trees that fell between 2011 and 2015 (including branch fall) and losses due to combustion and decomposition. Larch seedlings (<1.37 m tall) decreased by 34% in once-burned plots and decreased by 84% in twice-burned plots. The decrease in once-burned plots is primarily due to growth of seedlings into the sapling size class (>1.37 m tall), while the decrease in twice-burned plots is due to fire-caused mortality. The logistical complexity of backcountry travel makes case studies from wilderness areas rare. However, wilderness areas provide an important reference for understanding the role of uninhibited fire in forest ecosystems. This study shows that shorter fire return intervals lead to lower woody debris loads and seedling densities, maintaining forest conditions.
We're All Stressed, It's College: An Exploration Into the Perceptions of Stress Among College Students
Shelby Lambdin, The University Of Montana
1:40 PM - 2:00 PM
Between jobs, clubs, classes, families, roommates, social expectations and the transition into adulthood, the traditional aged college student faces a great deal of stress in their day-to-day lives. Adding to the perplexities of this topic, each individual experiences different perceptions of stress. Physical activity is often recommended to reduce stress, but little research has been done in the context of the benefits of physical activity and stress reduction in college students. This research compares two specific groups of college students that fall within specific criteria. The comparison will be made between any differences in perceptions of stress between students who are "runners" or students who "practice meditation". The criteria being that each group's demographics are college students from 18-25 years old. Students in group one will be those of a group from the University of Montana who are "runners" which is defined as participants who run 3-5 times for 20 minutes or more a week for this research. Students in group two will be those of a group from the University of Montana who practice meditation which is defined as participants who meditate 3-5 times for 20 minutes or more a week for this research. Students from each group will be given a survey consisting of questions related to their demographics, frequency of exercise, their perceptions of stress, and coping methods (if any) for stress. Information and data from these surveys will be compared and contrasted. This research will highlight whether or not exercise or mindfulness is more effective, or equally effective in providing positive perceptions of stress. Stress was the top health impact on academics for University of Montana students surveyed by the American College Health Association in the spring of 2014; so finding possible outlets for reduction of stress will provide valuable insight for administration and students.
Using Feather Corticosterone to Help Understand the Relationship Between Physiology and Nestling Growth in Mountain Bluebirds (Sialia currucoides)
Ian Morrison, University of Montana, Missoula
2:00 PM - 2:20 PM
Early developmental stress has a variety of effects that can persist to adulthood. Understanding how animals alter their developmental trajectory in response to stress is therefore a crucial goal for biologists. Corticosterone (CORT) is the primary avian stress hormone that is secreted from the adrenal gland in response to a challenge. CORT is a useful tool for measuring condition, as it integrates changes in external condition with internal coping responses. Typically CORT is measured in blood samples, but this only allows for insight into physiology during the instant of the sampling. Extracting hormones from feathers is a new method that can give longer-term insight on nestling physiology. Feathers grow over long time periods, and CORT is deposited throughout growth making it an ideal tool to study hormone physiology over a significant portion of development. I will extract CORT from Mountain Bluebird nestling feathers using methods developed by Bortolotti et al. (2008). I will run the samples through a standard radioimmunoassay to measure CORT levels in each sample. Mountain Bluebird nestlings grow in a logistic pattern and I am interested in understanding when nestlings reach their peak growth rates and how CORT and other factors such as hatch date, brood size, and brood rank explain differences between individuals. To answer these questions, I will use 269 feather samples that were gathered from Mountain Bluebird nestlings during the summers of 2014 and 2015. This research will help us to understand how physiology is altering development and growth of nestlings experiencing different environmental factors.
Can GPS Clusters Predict Calving of Moose in Northeastern Washington?
Richard Ramirez, University of Montana, Missoula
2:20 PM - 2:40 PM
Moose (Alces alces) populations are declining in many parts of their range, but the causes of these declines are not known. It has been suggested that low birth rates may be one reason for these declines. Estimating birthrates for wild populations, however, is often difficult and expensive. As new technologies are incorporated into wildlife research, novel approaches to estimating birth rates are waiting to be discovered. One specific way new technologies are being used in wildlife research is through the use of radio collars that save and transmit location information through satellites. For example, researchers studying wolves have used this location information to identify kill sites by patterns of restricted movement. Until now it has been very hard to determine birth rates for moose populations. The goal of my project is to test whether we can use GPS location information to identify when and where moose cows give birth. I will use data gathered by the Washington Moose Demography Project. This data was collected from 67 collared cow moose in the early summer of 2014 and 2015. This novel method I am developing may be an effective and low-cost tool for estimating moose birth rates.
Improving Classification of Transposable Elements in the Human Genome
Gilia R. Patterson, University of Montana - Missoula
4:00 PM - 4:20 PM
Transposable elements (TEs) are sequences of DNA that can replicate and reinsert themselves in the genome. Remnants of TEs are annotated and classified into subfamilies based on their DNA sequence. A subfamily represents all the remnant copies generated in a burst of replication by one parent TE. Biologists use subfamilies to study genetic diseases and to figure out evolutionary relationships (e.g. between human sub-populations), so it is important that TE remnants are classified accurately. We evaluated how accurately the current method annotates and classifies TE remnants in the human genome using a database of known segmental duplications. When a segment of genome with a TE remnant is duplicated, the TE remnants in each copy come from the same parent and should be assigned to the same subfamily. We identified the location and subfamily of all TE remnants in all segmental duplications and compared them. We found that a large fraction of TE remnants are assigned to different subfamilies, raising concerns about the quality of current subfamily classification methods.
Fish Food: Characterizing Aquatic Invertebrate Communities on the Upper Clark Fork River
Nicholas S. Voss, The University Of Montana
4:20 PM - 4:40 PM
The 2015 RESPEC Clark Fork River Fishery Assessment identified a reach of the Clark Fork River between Rock Creek and Flint Creek with low trout densities relative to the rest of the river. While examining a variety of potential causes, researchers noted a lack of information on aquatic invertebrate communities, which are a critical food source for trout. To investigate whether benthic invertebrates might account for the difference in trout densities, I used a kick net, yard stick, and flow tracker to sample aquatic invertebrate communities in six locations (three in a low trout density reach and three in a high trout density reach) on the river with consistent depth and flow velocity. This study investigates potential differences in invertebrate biomass, density, and taxonomic diversity that may explain the disparity in trout density between these two reaches. Invertebrate assemblages are also useful as bio-indicators of pollution or other larger issues affecting the ecosystem. When the samples are fully analyzed, this study may shed light on the ecological context of this disparity in trout density, and may better inform fisheries managers so that they can manage the Clark Fork River as effectively as possible.
To Jump or Not to Jump: Mule Deer and White-tailed Deer Crossing Decisions
Emily Burkholder, University of Montana, Missoula
4:40 PM - 5:00 PM
Wildlife meet energetic requirements for maintenance, reproduction and survival by considering the physiological, biotic, and abiotic factors that regulate energetic costs. These can include demographic, climatic and anthropogenic factors. The purpose of this study is to investigate fence crossing decisions of mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) and determine what factors influence their crossing decisions. I hypothesize that deer will choose to cross under a fence rather than jump over if it’s more energetically beneficial, based on measured physical and abiotic attributes. Data from remote cameras was collected and analyzed from three study areas; two in Southeastern Alberta, Canada and one in Northcentral Montana. Using a Before-After-Control-Impact (BACI) design, cameras were set up along fence lines within each study area. I recorded individual’s species type, age, sex and crossing decision. I also recorded the season, bottom and top wire height, snow presence, and the modification-type of the fence. I used logistic regression to model the probability of deer crossing under a fence versus jumping over it based on important fence and environmental characteristics. My results show that males and white-tail deer are less likely to cross under than females and mule deer. Both species are more likely to cross under during the summer and fall in reference to spring. Deer are less likely to cross under during the winter than in spring, however it was not statistically significant (P-value>0.05). As the bottom and top wire heights increase, deer are more likely to cross under. Snow presence, modification-type, and before/after periods were not included in the model because they were found to be statistically insignificant. Understanding the determinants behind either crawling under or jumping over a fence and how energetic requirements are associated with this decision is important to discerning animal movement for management and conservation practices.