|Friday, April 17th|
Ellen Brandell, University of Montana - Missoula
1:40 PM - 2:00 PM
Cougars (Puma concolor) and wolves (Canis lupis) are top predators that influence the dynamics of an ecosystem, including prey behavior and dynamics, and interspecific competition. I am examining co-occurrence between wolves and cougars in the Central Alberta Rockies using occupancy modeling. I hypothesize that cougars will be pushed out of higher quality habitat in the presence of wolves, to higher elevations, more rugged terrain, and areas with lower NPP than the areas occupied by wolves. There is a system of 167 remote wildlife cameras in Banff, Jasper, and Yoho National Parks; I am using the 2013 data for analysis. I have separated the data into logical seasons to better understand cooccurence patterns, summer (May 1 – October 31) and winter (Nov 1 – April 30), and it is separated into seven-day increments. From naïve occupancy models, summer cougar occupancy is 0.35 with a detection probability of 0.202 and winter occupancy is 0.157 with a detection probability of 0.0674. Summer wolf occupancy is 0.625 with a detection probability of 0.209, while winter occupancy is 0.435 with a detection probability of 0.134. The larger proportional, seasonal difference for cougar occupancy is intriguing because prey density is higher during the winter, meaning cougar-wolf competition may increase during winter; wolf presence may impact cougar detection and occupancy. This will be explored in the study, as well as covariates describing cougar and wolf occupancy separately and together. This study is important because the literature about wolf-cougar cooccurence provides mixed results: mostly cougars are secondary predators to wolves, but occasionally, cougars are unaffected by wolf presence. Understanding these interactions in this specific site will add to the literature and provide insight into the study ecosystems.
Sara Feilzer, University of Montana - Missoula
2:00 PM - 2:20 PM
The FBF proteins (FBF-1 and FBF-2) are critical to stem cell maintenance in the nematode, Caenorhabditis elegans. The hermaphroditic C. elegans initially produce sperm, and then continue with oogenesis. The FBF proteins function by regulating the transition between mitosis and meiosis by suppressing translation of specific mRNAs into proteins. FBF-1 and FBF-2 also regulate the sperm to oocyte switch in the hermaphrodite, and when FBF protein function is disrupted, there is complete sterility in the nematode. The objective of this research is to determine if certain components of pre mRNA splicing machinery have an effect on FBF protein function. For this research, an RNAi assay was used to disrupt the splicing factor function, and determine the effect of this disruption on FBF function in mutant or control worms. In two mutant strains, either FBF-1 or FBF-2 were functioning in isolation, and the control worms had both FBF-1 and FBF-2 functioning normally. The strains were synchronized by bleaching, and placed on RNAi plates containing bacteria that had been transformed to target the splicing factors of interest. The C. elegans were allowed to grow to adulthood and then the number of fertile adults were counted and recorded. Of the six total splicing factors studied, three of the knock-downs show a possible effect on FBF-2 protein function when it doesn’t have FBF-1 as a backup, two have little to no effect and one produces complete sterility in all strains. This research uncovers what could be an exciting link between RNA splicing in the nucleus and regulated protein production in the cytoplasm necessary for stem cell maintenance.
Charles "Alex" Knox, University of Montana - Missoula
2:20 PM - 2:40 PM
For most of the 3.5 billion year history of life on Earth, organisms were confined to a single-celled existence. When some lineages made the transition from single-celled to multicellular life, there were profound implications both for the planet and the organisms that remained unicellular. A leading hypothesis suggests that predation drove this important evolutionary transition in some multicellular lineages. In recent experiments, populations of the unicellular green alga Chlamydomonas reinhardtii evolved simple multicellular structures under selection on settling rate or from predation. C. reinhardtii is a model system for genetics, photosynthesis, circadian rhythms, flagellar motility, and sexual and asexual reproduction. I tested whether and to what degree simple multicellularity provides a viability advantage for C. reinhardtii exposed to two of its natural predators by comparing growth rates of unicellular and multicellular strains with and without predators. I found that multicellularity provides a meaningful advantage for C. reinhardtii with respect to predation under laboratory conditions. This provides support for the hypothesis that predation was an important factor in the evolution of multicellular lineages leading to the vast diversity seen in life today.
Jameson Boslough, University of Montana - Missoula
2:40 PM - 3:00 PM
2,4-dichlorophenoxyacetic acid (2,4-D) is the third most commonly used herbicide in the U.S., thanks to its ability to selectively control broad-leaf plants. The pathways enabling 2,4-D degradation in microbes are well characterized, and many native soil microbes are known to either possess plasmid or chromosomally-encoded DNA for such. Selection for 2,4-D degraders is known to occur in soils exposed to 2,4-D in-situ or in lab. However, there have been limited experiments in understanding how soil microbial populations from different, previously untreated soils respond to 2,4-D exposure, and the ecological dynamics of which specific pathway variants are selected for within each population due to herbicide concentration. We set out to explore these dynamics in 2,4-D naive soils around the Missoula Valley. Soils with no or minimal prior herbicide exposure were taken from the Garden City Harvest farm at River Road and from Mt. Sentinel. These soils were then amended in triplicate with either 2,4-D to 500 ppm, or with phosphate-buffer as a negative control, then incubated at room temperature in the dark over the course of several weeks. The amount of 2,4-D in the treated samples was monitored using HPLC and the soils were respiked to the initial concentration when≥80% had been degraded during the course of the experiment. At weekly intervals, the number of 2,4-D degraders in each sample were enumerated using MPN and 2,4-D minimal medium, while total aerobic, heterotrophic counts were obtained by plating on R2A general growth medium. Once the amendment series is completed, we will further analyze how each soil microbial community has responded based on genetic marker surveys. With further testing and experimentation, our research has the potential to illuminate the selective and ecological dynamics of soil microbial communities in response to 2,4-D exposure.
Nikita Cooley, University of Montana - Missoula
3:00 PM - 3:20 PM
Extremes of body size captivate biologists. In insects, the lack of extant giants has prompted the question, what is constraining insect size? While multiple physiological and ecological hypotheses have been presented, there is no widely accepted explanation. One unexplored physiological hypothesis is that large insects are unable to shed metabolic heat rapidly enough and are at increased risk of overheating. My project examines this idea using larvae of the Japanese rhinoceros beetle (Trypoxylus dichotomus), chosen for their huge size, simple body plan, and underground lifestyle. Using CO2 respirometry, I measured larval metabolic rates at room temperature. Although these beetle larvae are among the largest insects ever measured, their metabolic rates fell squarely on the expected values extrapolated from other, smaller insects. This permitted me to build a simple mathematical model of heat balance for insects across a wide range of body sizes. Specifically, I converted my measured rates of gas exchange into rates of metabolic heat production, and used the model to predict how much equilibrium body temperature would increase in insects larger than naturally occur. I then used CO2 respirometry during temperature ramping experiments to determine thermal tolerance limits. This showed that larvae could survive temperatures of 46-48˚C. Together, these show that for every 100-g increase in body size, there is a 0.5˚C increase in equilibrium body temperature, and that body temperatures are predicted to be well below the thermal maximum for animals ten times larger than any extant insect. In addition, larvae placed on runways extending across a thermal gradient were surprisingly active, and clearly capable of behavioral thermoregulation through movement to cooler locations. Collectively, my results suggest that insect size is not limited by metabolic heat production. This study provides a greater understanding of insect size constraints and behaviors associated with thermal regulation.
Sarah Kinsey, University of Montana - Missoula
3:20 PM - 3:40 PM
When someone is diagnosed with asbestosis (a chronic lung disease caused by inhaling asbestos fibers), there are few treatment options, none of which can halt or reverse the progression of the disease. The adverse health effects of asbestosis are due, in large part, to the response of the lungs to the asbestos fibers. Cells in the lungs deposit collagen around the fibers in an attempt to contain them, but this results in fibrosis and scaring of the lung tissue, making it difficult to breathe. In our studies we aimed to reduce the response of the lungs to the asbestos fibers using gene therapy techniques. If successful, this could offer a new avenue of potential therapy for those who have already been exposed to asbestos. A protein called SPARC (Secreted Protein Acidic and Rich in Cysteine) has been identified in previous studies as being important in the deposition of collagen and the fibrosis response. We interrupted the expression of this protein using a small interfering RNA molecule (siRNA) which we delivered via a viral vector. After identifying the most effective viral vectors in cells, we began our studies in mice. Mice in our study were first exposed to asbestos or a control solution and then, 2 months later, to our active virus or a control virus. After a month waiting period their lungs were analyzed: 1. histologically, to visually observe the presence of fibrosis, 2. Using RT-PCR to measure the presence of SPARC mRNA, 3. Using a Western Blot to measure the presence of collagen. If our results are consistent with our hypothesis, we will observe that the mice treated with active virus after asbestos exposure will experience less fibrosis and have less SPARC mRNA and less collagen in their lungs than the mice receiving the control virus.
Sarah Zundel, University of Montana - Missoula
3:40 PM - 4:00 PM
Lake Erie is the most productive and economically important fishery in the Great Lakes. In Lake Erie, Walleye (Sander vitreus) are one of the most sought after fish species. Because of their economic importance, fisheries biologists are studying their mortality, spatial ecology, and spawning migration movements. To estimate mortality in large aquatic ecosystems, we often tag individual fish and follow their fate. The capture, handling, and tagging procedure can result in stress and mortality that need to be determined for accurate estimates of annual natural mortality. The purpose of my project was to use acoustic telemetry to determine the post-tagging mortality of 100 Walleye in the Sandusky River stock and examine whether mortality rate was associated with sex, size, or date released. Walleye were collected in the Sandusky River over the course of three days: the 2nd, 10th, and 16th of April 2014. Once captured, individuals were implanted with transmitters and released. There were a total of six receivers used to detect tagged individuals moving downstream from the spawning area. The number and pattern of detections from each individual was used to determine mortality. Twenty-two Walleye (15 males and 7 females) out of 95 non-harvested Walleye (46 males and 49 females) died within the river or bay during the observation period, which ran from the release date to early June. There was no statistical difference in mortality between individuals based on length, sex, or release date. Now that the post-tagging mortality has been determined, the surviving Walleye will be used to determine natural mortality when they return next season to spawn.
Jessica Lindsay, University of Montana - Missoula
4:00 PM - 4:20 PM
Caterpillar species possess a range of anti-predator defenses, from regurgitation to sonar jamming. The North American walnut sphinx caterpillar (Amorpha juglandis) produces a variety of whistling noises when pinched. Limited observations indicate that this causes avian predators to retreat, leaving the caterpillar alone. However, it is unknown why this whistle is such an effective deterrent. Interestingly, the A. juglandis whistle is acoustically similar to the “seet” alarm call that many bird species produce in response to their own predators. We tested the hypothesis that the caterpillar whistles mimic bird alarm calls by playing recordings of A. juglandis whistles, chickadee seet calls, and a control sound to flocks of small songbirds and comparing the birds’ responses to the different stimuli. Birds tended to freeze or dive for cover in response to the seet call and two types of caterpillar whistles. Our results suggest that these caterpillar whistles may protect caterpillars by mimicking the alarm calls of their avian predators.