|Friday, April 28th|
Zhibing Zhou, University of Montana, Missoula
9:20 AM - 9:40 AM
Mariah McIntosh, University of Montana
9:40 AM - 10:00 AM
The obligate fungal mutualists arbuscular mycorrhizal fungi (AMF) colonize the roots approximately 80% of vascular plants, generally thought to provide mineral nutrition, pathogen protection, or drought resistance to plants in exchange for photosynthetic carbon. Because of the ecological and evolutionary significance of these interactions, much work has been done to understand this symbiosis at the community level. However, much remains to be understood about how AMF affect plant fitness on an individual level. In this study, I took advantage of the tractability of the emerging model species Mimulus guttatus, the common yellow monkeyflower, to identify genetic differences in how contrasting annual and perennial populations respond to AMF. Specifically, I tested for differences in plant dependency on AMF, and variation in local adaptation to native AMF communities. I conducted a full factorial common garden greenhouse experiment using plant, soil, and inoculum from each contrasting field site. I found no dependency on AMF in either population and no local adaptation to native AMF communities. These results suggest that there is little genetic difference in how these contrasting annual and perennial populations interact with AMF. The presence of AMF did not confer a fitness advantage to either plant type and was often associated with a fitness cost, despite differences in life history, providing evidence for a potentially antagonistic relationship between M. guttatus and AMF under certain conditions, consistent with the theory that more ruderal species are less likely to benefit from AMF.
Haley N. Shepard, University of Montana
10:00 AM - 10:20 AM
How behavior and information is encoded in brain circuits and how individual neurons influence these brain circuits is a growing question in neuroscience. In the nervous system of many organisms, including humans and Drosophila, exists a subset of neurons that are capable of releasing more than one neurotransmitter, a phenomena called co-transmission. How co-transmission may alter circuits dedicated to behavior is a challenging question. To begin to answer this question we used the genetic tools available in Drosophila to investigate how the release of two neurotransmitters from a single neuron can alter aggression. Astrocytes surround the synapses of neurons that release glutamate and prevent accumulation of glutamate at the synapse by removing it using the Excitatory Amino Acid Transporter 1 (EAAT1). We obtained Drosophila stocks that, when crossed to one another, produced knockdowns of the EAAT1 in the astrocytes in order to observe any changes in aggression caused by inhibition of glutamate reuptake. We used behavioral assays to observe any differences in behavior between EAAT1 knockdown animals and control animals. In our preliminary data we did not observe enhanced aggression in Drosophila males as a result of EAAT1 knockdown. This study suggests that higher amounts of glutamate may not produce enhanced aggression in Drosophila.
Glutamate may be the most abundant neurotransmitter in the CNS. Therefore, it is vital that we understand how glutamate affects individual neurons, entire brain circuits, and behavior. If we can better understand the role of glutamate in disorders that are connected to an increase in aggressive behavior such as dementia, schizophrenia, and traumatic brain injury, then more effective medications and interventions can be developed to treat these disorders.
Clare E. Vergobbi
10:20 AM - 10:40 AM
Whitebark pine (Pinus albicaulis) is a high elevation tree in serious decline.. It is experiencing high mortality due to white pine blister rust, an exotic disease, and outbreaks of the native mountain pine beetle, as well as the effects of climate change. It is unknown how this massive mortality has altered the genetic diversity of whitebark pine populations. Furthermore, large die-offs can act as strong selection events, removing individuals with lower fitness. It is possible that survivors of mountain pine beetle outbreaks have different genotypes than trees killed and may be better adapted to current and future warmer drier climates.
This project uses Inter-Simple Sequence Repeats (ISSR), a method that detects high levels of genetic polymorphism, to test two hypotheses: 1) surviving trees differ genetically from those that are killed by the beetle, and 2) the outbreak has reduced overall genetic diversity in affected stands. Needles were collected from surviving trees after a beetle outbreak and from trees just under the minimum diameter beetles attack. The smaller trees were used a surrogate for the ‘general population’ pre-beetle selection. DNA was extracted from the needles and screened with three ISSR primers using PCR and gel electrophoresis to analyze genetic differences between individuals. Survivors and a few general population trees clustered distinct from other general population trees indicating distinct genetic differences among survivors and those selected by the beetles. This suggests that selection may be occurring in these populations as a result of the beetle outbreaks.
Information gained in this study will help develop a more informed approach to whitebark pine restoration and forest adaptation to climate change.
Mackenzie Prichard, University of Montana
1:40 PM - 2:00 PM
All vertebrates respond to stressful situations through the release of hormones called glucocorticoids (CORT). These hormones alter processes within the body to prioritize long term survival over immediate reproduction. It is hypothesized that this is helps individuals survive until conditions become more favorable for successful reproduction. Historically, stress was hypothesized to primarily to pull organisms out of reproductive life history stages when unfavorable conditions made offspring survival slim (otherwise known as the “CORT-tradeoff hypothesis”). However, recent evidence suggests that birds actively feeding nestlings show elevated CORT levels, possibly due to the increased metabolic demands of parenthood. This relationship has been named the “CORT-adaptation hypothesis”. This research tested these two conflicting associations between parental effort and stress hormones to further understand the complex relationship between stress and reproduction. During the summer of 2016 I collected blood samples to examine the levels of CORT in female tree swallows in the Seeley-Swan valley of Montana. To measure parental effort, I observed and recorded various parental behaviors including time incubating, feeding rates, and nestling growth. I compared relationships between these measurements to help explain the relationship between reproduction and CORT.
Jeremy Brooks, University of Montana, Missoula
2:00 PM - 2:20 PM
Aquatic communities, species that live and interact with each other, each have a unique composition and function (i.e collection of decomposers, predators, and grazers). Broad ecological theory provides a variety of models that can predict communities and their functions across riverscapes. For example, the River Continuum Concept (RCC) explains general shifts in stream communities and their function along longitudinal (upstream to downstream) gradients, but it fails to consider the more narrow effects of tributaries and confluences. Conversely, dendritic stream networks theory helps explain the potential role of river confluences and how they connect communities, but fails to explain general longitudinal shifts in communities. This discontinuity between models begs for a way to integrate the role of confluences (dendritic theory) into a broader landscape model (RCC). I hypothesized that river confluences would have a different influence on community diversity and function than expected under the RCC. To explore this, I sampled aquatic insects at tributaries along a watershed to test predictions that stream confluences would (1) increase insect diversity (number of species), (2) abruptly change specific species abundance, and (3) change the overall community function through increasing and decreasing insect functional feeding groups. I collected aquatic insects in two watersheds in the Beartooth-Absaroka Wilderness, sampling above and below four stream confluences in each watershed. Aquatic insect samples were identified to genus level and given a functional feeding group score. I will examine pairwise upstream/downstream differences with and without intervening confluences to compare community diversity, composition, and functional diversity. Streams ecosystems are often ranked as one of the most imperiled ecosystems in the world. Developing aquatic community theories and models as we work to restore these ecosystems is important in understanding how pristine aquatic ecosystems should function.
2:20 PM - 2:40 PM
An ongoing study on the Charles M. Russell Wildlife Refuge (CMR) is testing the efficacy of a bait-administered sylvatic plague vaccine. This entails distributing vaccine and placebo baits within paired prairie dog colonies. On the CMR, the target species for this vaccine is the black-tailed prairie dog (Cynomys ludovicianus), an important prey species for the endangered black-footed ferret (Mustela nigripes). For my senior thesis project, I am collaborating with the sylvatic plague vaccine project by examining whether there is a difference in monthly survival between non-target small mammal populations living on prairie dog colonies treated with vaccine baits and those on colonies treated with placebo baits. Non-target small mammal species on my field sites include deer mice (Peromyscus maniculatus), and northern grasshopper mice (Onychomys leucogaster). My field work consisted of trapping on three sites comprised of paired vaccine and placebo plots (6 total plots) during the summer of 2016. Trapping sessions were between three and four days with approximately 4 weeks between sessions, and were repeated for four or five months. To estimate apparent survival, I have used a robust design, multi-state model to analyze capture histories in program MARK. During the field trial stage of the sylvatic plague vaccine, it is important to determine how vaccine bait application affects both target and non-target species within and around prairie dog colonies before widespread application is undertaken. Reducing plague infection among prairie dogs and other rodents may thereby reduce transmission to species such as the endangered black-footed ferret, domestic animals, and humans.
2:40 PM - 3:00 PM
Kill rate, defined as the number of prey killed per predator per unit time, is a key component to understanding predator-prey dynamics. A multitude of factors may affect kill rates, including, variation in age, sex, weight, or presence of offspring of either predator or prey species (intraspecific variation) and events such as the theft of a kill made by another animal (kleptoparasitism). These factors may influence the time a predator spends locating prey (search time) and the pursuing, killing, and consumption of prey (handling time). The sum of search time and handling time may be measured as the time between a subsequent kill, a metric I will use to make inferences on what affects mountain lion (Puma concolor) kill rates. Utilizing kill data obtained from GPS-collared mountain lions of Colorado, Wyoming, and Patagonia, I plan to investigate the impacts of: 1) mountain lion sex, 2) mountain lion age, 3) accompaniment of offspring with mountain lion females, 4) prey weight, and 5) the presence of bears (habitual kleptoparasites) throughout study periods. Applying these factors, I aim to find the most parsimonious and biologically sound statistical model, best describing sources of variation in time between kills for mountain lions. Further knowledge on this subject may be useful for the management of mountain lions.
4:20 PM - 4:40 PM
Retired outfitter Smoke Elser insists upon the utmost importance of “interpreting the land” in the outfitting business, and in my time packing and guiding I have come to appreciate the role of the interpreter in transmitting a particular landscape’s intertwining geography, ecology, and cultural history through storytelling. The Lay of the Land: Three Years in the Bob Marshall Country is intended to carry on this tradition, while adapting it to my own perspective as a young man in the social conditions of the 21st century.
The work is a compilation of narrative essays which explore the landscape and culture of the Bob Marshall Wilderness and the surrounding communities. These stories, drawn from my journals taken while working in the Bob, will remain grounded in the cultural history of the region, lending a broader perspective on my role in the story. An accompanying literature review will also analyze techniques used to create a geographical identity in Bernard DeVoto’s historical narratives and Ivan Doig’s personal narratives, then examine how those techniques may be applied in my own work to build on the lineage of Howard Copenhaver and Bud Cheff’s stories from the Bob. It is my intention for the work to imbue the reader with a sense of place and cultivate an ecological conscience based upon the life of the Crown of the Continent.