oralandposterpresentation abstracts ·...

2014 Program in Ecology (PiE) Student Research Symposium Program 1

Program in Ecology’s

Ecology Student Symposium

February 21, 2014

Berry Biodiversity Conservation Center, University of Wyoming, Laramie Wyoming

Oral and Poster Presentation Abstracts


Schedule Overview

Friday, February 21st 12:00 pm–12:10 pm Opening Remarks: Dr. Khaled Gasem, Associate Provost of Graduate

Education & Interim Dean of College of Engineering and Applied Sciences 12:10 pm–1:00 pm Keynote Speaker: Robert P. Guralnick, Associate Professor, University of

Colorado at Boulder • “Developing a Map of Life: A Conceptual and Cyberinfrastructure

Framework for Documenting Global-‐scale Biodiversity and Monitoring its Change”

1:00 pm–1:30 pm Break 1:30 pm–2:30 pm Session 1: Student Speakers

• Carolyn Eckrich, Susma Giri, Christa Cooper Sumner, Embere Hall 2:30 pm–2:45 pm Break 2:45 pm–3:45 pm Session 2: Student Speakers

• Beth Fitzpatrick, Lynn Moore, John Frank, Reilly Dibner 3:45 pm–4:00 pm Break 4:00 pm–4:45 pm Session 3: Student Speakers

• Guinevere Jones, Hilary Madinger, Charlotte Gabrielsen 4:45 pm–5:00 pm Closing Remarks: Dr. Matthew Kauffman, Department of Zoology and

Physiology, Program in Ecology, University of Wyoming 5:00 pm–8:00 pm Poster Session/Darwin Day Party

• Enjoy dinner and refreshments while speaking with student presenters • Raffle fundraiser

Keynote Speaker: Robert P. Guralnick

TIME 12:15 "Developing a map of life: a conceptual and cyberinfrastructure framework for documenting global-‐scale biodiversity and monitoring its change"

Dr. Robert P. Guralnick and his lab’s research focus on spatiotemporal changes in genetic and species

diversity. They take an integrative approach to global change biology, and the tools they use in their lab range from occupancy models to spatial ecological models, landscape genetics, and molecular phylogenetics.


Oral Presentations

1:30 High spatial variation in the consumer isoscape: is it individual specialization?

Carolyn Eckrich1, Elizabeth Flaherty2, and Merav Ben-‐David1

1Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY 2Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN Abstract

The isotope ratios of all potential food sources in an area allow for estimation of the diet of consumers within that area. In addition to diet selection, habitat use may also affect the δ13C and δ15N values of consumers. Small mammals in Southeast Alaska live in a landscape of habitat patches comprised of old-‐growth, young-‐growth, thinned and clearcut forest stands. Keen’s mice (Peromyscus keeni), an omnivore and dietary generalist, and dusky shrews (Sorex monticolus), an insectivore specialist, occupy all habitat types on Prince of Wales Island (POW), Alaska. We used stable carbon and nitrogen isotopes to estimate the diets of sympatric mice and shrews on POW across these habitat types and at six different landscape locations. We also collected and analyzed all potential prey items. Multi-‐source dual-‐isotope mixing models were used to determine the range of possible contributions of each food source. Mice exhibited variation of up to 7‰ in δ13C and 11 ‰ for δ15N between habitats and across the landscape. The relatively wide isotopic niche of mice suggests either specialized foraging behavior of individuals or faithfulness to specific foraging habitats. This study highlights the importance of considering habitat use as well as diet selection when examining isotopic patterns of consumers.

1:45 Study of Homeoviscous adaptation in native bees of Wyoming

Susma Giri and Michael E. Dillon Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Fatty acids (FAs), key components of lipids, are important energy resources in organisms. The structure and function of these FAs are affected by changes in environmental temperatures, ultimately impacting organism physiology. However, both plants and animals are capable of adapting to these changes in temperature, by adjusting their FA composition, thus altering FA fluidity in part, a hypothesis termed as 'homeoviscous adaptation'. FA fluidity is measured as the ratio of unsaturated to saturated fatty acids (UFA: SFA). Insects, being ectothermic, are particularly vulnerable to the changes in environmental temperature. Pronounced thermal gradients across seasons and altitude are likely to challenge lipid physiology in insects. We compared UFA: SFA and unsaturation index (UI) in four native bee genera (Andrena, Bombus, Megachile & Osmia) collected throughout the growing season (May through September) at two different altitudes in Wyoming. The fatty acids in samples were derivatized and analyzed using GC-‐FID. Preliminary analyses suggest that both UFA: SFA and UI in Osmia are significantly higher at higher altitudes and vary within season. This data provides a new line of evidence for the homeoviscous adaptation in native bees.


2:00 Visitor perceptions of bark beetle impacted forests in the Rocky Mountains: Preliminary findings

Christa Cooper Sumner Department of Philosophy, Program in Ecology, University of Wyoming, Laramie, WY Abstract

The Rocky Mountain landscape has undergone dramatic changes in recent years due to bark beetles. These changes are seen across ecosystem levels, including human dimensions, such as the way people perceive and interact with the environment. In July 2013, a survey was given to visitors at Rocky Mountain National Park. This survey was aimed at gaining a greater understanding of how these changes are being perceived and understood by visitors. Findings to be discussed include visitor awareness and knowledge of bark beetles and their impacts, as well as general perceptions of the current forest landscape including whether it is seen as beautiful or ugly, natural or unnatural, and tame or wild.

2:15 Habitat use in a changing environment: A story of cold stress in a heat-‐sensitive mammal

Embere Hall1, Anna Chalfoun2 and Kerry Murphy3 1Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY 2US Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology, University of Wyoming, Laramie, WY 3U.S. Forest Service, Bridger-‐Teton National Forest, Jackson, WY Abstract

Contemporary climate change has altered classic extinction dynamics. Consequently, wildlife conservation efforts must consider habitat use patterns under novel conditions. American pikas (Ochotona princeps) are an ideal species for evaluating climate-‐driven changes in habitat use because of their temperature sensitivity, dependence on snow and naturally patchy distribution. Relatively little is known about pika distribution or habitat use in the Greater Yellowstone Ecosystem. As a result, regional responses to climate change are largely speculative. To better assess pika habitat use, we examined pika occurrence at 132 sites on the Bridger-‐Teton National Forest, June-‐October 2010-‐12. We selected sample points in four elevation categories using a GRTS sampling design. At each site we surveyed for pikas in a 12m fixed-‐radius plot and used a 100m line-‐point intercept transect to quantify forage. We deployed 80 temperature loggers at a subset of points to better understand ambient and subterranean temperatures. Forty-‐eight percent of sites were occupied. Important predictors included elevation and subsurface temperature. Preliminary results indicate that cold exposure and snow cover may be drivers of pika habitat use. With snow depths predicted near zero in some alpine habitats by the end of the century, populations of pikas and other alpine mammals may face increasing difficulty.


2:45 Planning future restoration for long term persistence of a declining species

B. A. Fitzpatrick and M. A. Murphy Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Decisions on how to preserve or restore habitat are highly variable and depend on driving forces behind land management. In the intermountain west, energy development is a major driving force that is counteracted by the possible listing of a species: the Greater-‐Sage Grouse (Centrocercus urophasianus). To accomplish this, one of our goals is to understand how development influences functional connectivity of sage-‐grouse leks in Northern Wyoming. To assess functional connectivity, we collected non-‐invasive DNA samples from 87 sites and estimated genetic distance from a subset of those sites (n = 35). We present a pilot population network model based on relating 2012 field data to limiting factors across the landscape. We found that connectivity of sage-‐grouse leks is positively associated with amount of sagebrush habitat between sites and mean annual precipitation at-‐site and negatively associated with topographic roughness at-‐site. The population network model will be used to predict changes in functional connectivity in the face of different scenarios of landscape change. Our research will provide a scientifically-‐based decision-‐making tool for prioritizing development, protection, and restoration that will help stakeholders work towards a successful conservation outcome for sage-‐grouse.

3:00 Twelve years of high resolution near surface radiometer data provides insight into controls on end of season in a dry grassland

Lynn M. Moore Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY Abstract

The onset of dormancy has proven difficult to explain in nearly all ecosystems. Most research has focused on the end of season dynamics of deciduous ecosystems, where leaf coloration and leaf fall are the primary phenological responses. More complex are the end of season dynamics of grasslands, where the mechanism of dormancy is a gradual response to climatic variables. These complications are magnified in dry grasslands, where the effects of temperature on phenology are modulated by the availability of soil water. Our objectives were to identify the primary drivers influencing the timing of end of season on the shortgrass steppe and determine if the timing of start of season, end of season, or both influences the growing season length of the shortgrass steppe. The results of our study suggest that day length, temperature and soil water interact to influence the timing of end of season in the shortgrass steppe and growing season length is strongly related to the date of start of season and less so to the date of end of season. Our findings bear important implications for understanding semiarid ecosystems under climate change. Because future precipitation and temperature tend to diverge, understanding responses in seasonality of greenness as well as productivity in general must take both precipitation and temperature into account.


3:15 How much do bark beetles change the annual water cycle of a spruce-‐fir forest?

John M. Frank1,2, Brent E. Ewers2, William J. Massman1, and David G. Williams2 1U.S. Forest Service, Rocky Mountain Research Station, Fort Collins, CO 2Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Bark beetle disturbances in the forests of western North America have been linked to anthropogenic changes in land use and climate and to disruptions in ecosystem function and alterations in the hydrologic cycle of forests. Spruce beetle (Dendroctonus rufipennis) outbreaks impact subalpine forests that contribute to the headwaters of many western US watersheds. These epidemics influence annual water vapor fluxes by two distinct processes: (1) transpiration is reduced as attacked trees experience hydraulic failure due to the beetle associated blue-‐stain fungus and (2) as dead trees drop their needles, canopy leaf area is reduced which alters the dynamics of snow interception and sublimation. In this study, we analyze eddy-‐covariance flux data collected during a spruce beetle outbreak in a subalpine forest dominated by Engelmann spruce (Picea engelmannii) and subalpine fir (Abies lasiocarpa) in southeastern Wyoming, USA. Results suggest that growing season and wintertime water vapor fluxes are equally important for the annual water cycle and that in the first years following the outbreak both evapotranspiration and sublimation were reduced by 1/3. Our findings demonstrate that ignoring winter sublimation causes erroneous water budgets and ultimately streamflow predictions.

3:30 An ecological engineer maintains consistent spatial patterning across environmental gradients, with implications for community-‐wide effects

Reilly R. Dibner1 and Daniel F. Doak2 1Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie WY 2Environmental Studies Program, University of Colorado at Boulder, 397 UCB University of Colorado, Boulder, CO Abstract

In many ecosystems around the world, foundational species create spatial patterns that structure a broader community. It is unclear, however, how stable these patterns are across broad areas and strong environmental gradients. We investigated the stability of non-‐random patterns in the dispersion of the western harvester ant (Pogonomyrmex occidentalis), a widely recognized ecosystem engineer of the intermountain west. We used remote imagery to characterize the spatial structure and densities of harvester ant mounds at sites spanning their range within the sagebrush steppe and short-‐grass prairie areas of Wyoming. We found that ant mound densities varied substantially across the state, but that mounds were highly overdispersed (regularly patterned) across both environmental gradients and mound densities. Precipitation was the only abiotic factor that significantly affected either density or pattern, with more highly patterned mounds at lower rainfall gradients. This patterning stability is likely to have strong effects on community function; the patterning among mounds increased the fraction of the landscape within typical foraging distance up to 130% over what density alone would predict.


4:00 The effects of disturbance on the structure and functional diversity of cloud forest insect communities

Guinevere Jones Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Within the layers of montane Ecuadorian cloud forests exist both primary and secondary growth regions, complete with differing internal vegetation and forest structure. These forests are largely intact with the most recent period of disturbance happening roughly 50 years ago and continuing today; mostly to support agricultural-‐based endeavors, both private and commercial. This ongoing research is a study of six plots in varying degrees of human disturbance across an elevation gradient of 300m. Sampling was conducted every 12-‐hours to quantify both diurnal and nocturnal community activity and structure. Preliminary analysis between two study areas highlights differences in composition of ground and canopy insect populations. Insect functional diversity is also examined throughout the vertically stratified ecosystem. These results are used to build an early version framework of structure and function of the greater cloud forest ecosystem that is vital not only for other scientists studying in this region, but also for the economically important eco-‐tourism businesses.

4:15 Direct measurements of stream nitrogen fixation via membrane inlet mass spectrometry

Hilary L. Madinger1, Lisa A. Kunza2, Robert O. Hall1 1Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY 2Department of Atmospheric and Environmental Sciences, South Dakota School of Mining and Technology, Rapid City, SD Abstract

Nitrogen fixing bacteria convert N2 gas into biologically available nitrogen. Acetylene reduction assay is an indirect measurement of N2 fixation by assessing nitrogenase activity. Stable isotopes provide an accurate N2 fixation measurement; however, 15N tracer studies are challenging and expensive to conduct. Membrane-‐inlet mass spectrometers (MIMS) allow direct measurement of the dissolved gas concentration of water samples, but measure net N2 fixation and denitrification so measurements may be underestimated. We compared N2 fixation measurements from acetylene reduction and MIMS on cobbles with intact biofilm. To calculate change in N2 concentration using the MIMS we compared the measured N2 concentration to the predicted N2 based on the N2/Ar ratio. The N2 concentration decreased by 0.15% per hour where 0.66 µM/h of N2 was fixed using the MIMS methods. The ratio of moles of N2 lost to moles of ethylene produced was 0.98. Because a MIMS measures net change in N2 gas, using a MIMS rather than acetylene reduction assay is a promising technique for the measurement of benthic N2 fixation in streams.


4:30 Understanding wetland ephemerality in the context of climate change

Charlotte G. Gabrielsen1, Melanie A. Murphy1, and Jeffrey S. Evans2,3 1 Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY 2 The Nature Conservancy, Fort Collins, CO 3 Department of Zoology and Physiology, University of Wyoming, Laramie, WY Abstract Wetland ephemerality, the persistence of a wetland across the growing season, is sensitive to changes in precipitation, temperature and timing due to climate variation. Wetland ephemerality has major implications for wetland-‐dependent species and human water allocation. To identify wetland locations and characterize wetland ephemerality in the Plains and Prairie Pothole Region, we employed a probabilistic and multi-‐scaled approach using a combination of field-‐based observations and remotely sensed data. Using these results, we then linked wetland ephemerality to climatic variation by relating ephemerality to a climate time-‐series data. Finally, we predicted wetland ephemerality under a range of potential climatic conditions representing changes to temperature, precipitation, and timing. With the ability to monitor wetland habitat change and climate variability over time, this research will better inform conservation management decisions and improve the accuracy of climate change predictions in the region.

Poster Presentations

#1 Using data to help increase STEM retention rates for at-‐risk students; Student expectations and skill building

David E. Reed, Guinevere Jones, April Heaney University of Wyoming, Life Science Program University of Wyoming LeaRN Program Abstract

Retention in the STEM fields is often a focus for higher education due to a shortage of trained workforce members. In particular, much effort has been spent on first year retention rates and introductory level courses under the assumption that students are more likely to drop out of STEM majors early in their degree progress. The Synergy Program’s goal is to promote academic success and retention for underprepared and at-‐risk students by creating a series of first semester curricula as theme-‐based college transition skills courses. In this study we are highlighting the results of the STEM students as compared with other at-‐risk participants in the program. The Synergy Program enrolls approximately 144 students each year with pre-‐ and post-‐course surveys that directly measure which college skills students select as important as well as student expectations of the amount of time required for STEM courses. Follow-‐up surveys track the same queries for students who persist to their junior and senior year. This analysis will show other higher education instructors both the course design and results from this study of at-‐risk students. Our results will include specific strategies to enhance STEM retention while increasing the overall college success of at-‐risk freshmen through this innovative course design.


#2 Uptake of 15N tracer by different functional types across a sagebrush/ lodgepole pine ecotone

Caitlin M. Rottler1, Ingrid C. Burke2, Megan L. Mobley2, David G. Williams3, William K. Lauenroth3 1Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY 2Haub School of Environment and Natural Resources, Department of Botany, University of Wyoming, Laramie, WY 3Deptartment of Botany, University of Wyoming, Laramie, WY Abstract

As climate change, management, and environmental factors impact the distribution of ecosystems, plants will encounter, and possibly alter, different soil nutrient conditions. Our study seeks to characterize nutrient uptake in three functional groups across a sagebrush/lodgepole pine ecotone. In summer of 2013, we added 15N tracer to plants at three different depths to test the depth of the majority of nitrogen uptake for each functional type. Preliminary data indicate a significant difference in δ15N between experimental and control plants for grass (Festuca idahoensis) at 30cm and 60cm, and for sagebrush (Artemisia tridentata) at 10cm and 60cm. Data for trees (Pinus contorta) show a wide variation in δ15N values, with no significant difference between control and experimental plants at any depth. Predictions of future climate change in this region suggest that winter precipitation will decrease, potentially leading to a shift in the depth distribution of soil resources to surface horizons, and changes in plant functional types. The ability to quantify depth of nutrient uptake in these areas will assist us in understanding the dynamic relationship between soil resource distribution and plant functional type dominance.

#3 Application of stable isotopes to reconstruct Greater Sage-‐Grouse chick dietary history: Dietary selection and relative body condition

Kurt T. Smith1, Aaron C. Pratt1, Jeffrey L. Beck1, Dylan L. Bergman1, and Peter D. Stahl1 1Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Survival of chick greater sage-‐grouse (Centrocercus urophasianus) has compelling implications for persistence of sage-‐grouse populations. Nutritional demand during this life stage is high and availability of insects and forbs consumed by chicks is related to growth, body condition, and subsequent survival. Because chicks in the best body condition are likely to have higher survival, the abundance of forbs and insects in diets producing chicks in the best body condition provides important insights about the effects of diet on chick survival. In spring 2013, we initiated a study in south-‐central and north-‐central Wyoming designed to answer multiple objectives about chick sage-‐grouse diet selection and body condition. To determine diet availability (by weight) we collected insect and forb mass samples at brood-‐rearing and random locations. To quantify chick diets we are comparing the ratio of naturally occurring isotopes (δ15N, δ13C) in feathers to establish the relative contribution of forbs and insects in diets from hatch to week 5 post-‐hatch. To obtain body condition measurements we weighed captured chicks and measured their wing chord length to correlate with isotopic ratios. The relationship between chick diet selection and isotopic composition of feathers will allow us to 1) investigate diet selection relative to diet availability at brood locations, 2) understand brood site selection in relation to diet availability, and 3) assess the relationship between diet composition and chick body condition. In spring and summer 2013 we collected feather samples (2 chicks per brood) from 5-‐week-‐old chicks for stable isotope analysis to determine chick diets and forb and insect mass samples at 213 brood locations and 158 random brood locations representing n = 42 broods. A measure of body condition in relation to chick diet will provide us a means to assess the relative value of foods provided across an array of sagebrush habitats for sage-‐grouse.


#4 Fitness consequences from different migration behavior in Greater Sage-‐Grouse

Aaron C. Pratt and Jeffrey L. Beck Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Migration is an important behavior in the life history of many avian species, including greater sage-‐grouse (Centrocercus urophasianus). For sage-‐grouse, migration is motivated by changes in habitat quality as related to availability of food sources. Observations from radio-‐marked grouse in the eastern Bighorn Basin, Wyoming have revealed a wide variety of behavior expressed by individuals in the population. This has included areas used for summer habitat. Some of the marked grouse made farther altitudinal movements to mesic high-‐elevation sites whereas others made shorter horizontal movements to nearby hayfields. These differences in migration behavior, because of selection of different habitats, may impact the physical condition of the individuals, their survival and reproductive success, and subsequently the natural selection of different behaviors in the population. Therefore, our objective is to compare the body condition and demographic rates between grouse expressing different migration behavior. We captured and radio-‐marked female sage-‐grouse during 2011–2013 (n = 193) and will continue during 2014. To catalogue the history of migration behavior for the previous year for each captured grouse we will measure deuterium and nitrogen stable isotope signatures. We will then compare body condition, survival, and reproductive success between grouse demonstrating the two categories of behavior. #5 Competitive interactions among native snails and the New Zealand mud snail,

Potamopyrgus antipodarum, using grazing experiments and stable isotope analysis

Michele D. Larson1 and A. Ross Black2 1Department of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY 2Eastern Washington University, Department of Biology, 258 Science Building, Cheney WA 99004 Abstract

The New Zealand mud snail, Potamopyrgus antipodarum, is an invasive gastropod that can impact native gastropod populations. However, conflicting results from competition experiments between native gastropods and P. antipodarum has resulted in an ambiguous understanding of the impacts P. antipodarum may be having on native gastropods. We conducted grazing trials with the native gastropod, Fluminicola, under interspecific and intraspecific competition to aid in the understanding of how P. antipodarum may be impacting this native gastropod. We also conducted stable isotope analysis for two locations: one with P. antipodarum present and the other without this invasive snail. The interspecific grazing trials did not show effects of grazing due to competition, however, single snail treatments without competition showed 4.8 times higher gram-‐specific fecal mass in P. antipodarum than Fluminicola suggesting that P. antipodarum is a more efficient grazer. The intraspecific grazing experiment showed grazing effects with higher densities of Fluminicola resulting in higher grazing rates. Carbon stable isotopes suggest shared food resources among gastropods at the invaded location. Strong overlap between the proportional range of food sources for P. antipodarum and Fluminicola may indicate competition for food and a shift in the food resources used by Fluminicola in invaded areas.


#6 Surface and canopy fuels vary widely in 24-‐yr old postfire lodgepole pine forests

Kellen N. Nelson1, William H. Romme2, and Monica G. Turner3, and Daniel B. Tinker1 1Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY 2Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, CO, USA 3Department of Zoology, University of Wisconsin, Madison, WI Abstract

Extreme fire seasons have become common in western North America, and the extent of young post-‐fire forests has grown as fire frequency and annual area burned has increased. The rate of fuel re-‐accumulation and fuels variability in young forests will ultimately set the stage for future fires but an assessment of fuel loads in young forests is lacking. We studied fuel characteristics in 24 year old lodgepole pine forests in Yellowstone National Park to address two questions. (1) How do surface fuel characteristics develop with time-‐since-‐fire? (2) How do canopy and surface fuels vary across the landscape 24 years postfire? In 2012, we re-‐measured surface fuels in 10 plots established in 1996 (8 years postfire), and inventoried surface and canopy fuels in 82 stands distributed across the Yellowstone post-‐1988 fire landscape. In the remeasured plots, surface fuels <0.64 cm diameter did not change between sample dates, but all other woody fuel classes increased by a factor of two to four. Data from the landscape-‐wide inventory revealed that canopy and surface fuels in 24-‐year-‐old stands varied tremendously across Yellowstone National Park. Live tree densities spanned 0 to 344,067 trees ha-‐1, producing a mean and range of available canopy fuel loads of 7.73[0.0, 46.6] Mg ha-‐1. Total surface fuel loads averaged 133.6 and ranged from 49.4 to 228.2 Mg ha-‐1 where nearly 90% consisted of >7.62 cm-‐diameter wood. Our data indicate that much of the forest that regenerated after the 1988 fire has adequate canopy fuel to carry wind driven crown fire but insufficient surface fuels to sustain fire under moderate conditions. Substantial heterogeneity in canopy, surface and total fuels suggest variability in fire behavior and severity. Fuel mosaics in young forests will increasingly influence fire activity in western forests as the climate continues to warm and fire frequencies decline.

#7 Variation in the expression of the ecophysiological traits among croptypes of Brassica rapa

Yulia Yarkhunova, C. Edwards, Brent Ewers, and Cynthia Weinig Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY Abstract

Selection during domestication can result in dramatic changes in morphology. Brassica rapa (Brassicaceae) shows dramatic morphological differentiation as a consequence of domestication, with the evolution of leafy vegetable crops (subspp. pekinensis and chinensis), root vegetable crops with enlarged below-‐ground storage structures (subspp. ssp. rapa or rapifera), and oilseed crops with high seed allocation (subspp. oleifera).

Brassica rapa is an agronomically important species that is widely cultivated from the Western Mediterranean to Central Asia and in parts of N. America. The species also occurs in wild populations in disturbed roadside and hedgerow sites.

For our study, we used multiple genotypes within each of three different croptypes (turnip, cabbage, and oilseed) to test for possible physiological differentiation. We have found that there is a wide variation in gas-‐exchange traits, biochemical parameters, and morphological traits. In particular, oilseed have higher photosynthetic and stomatal conductance rates, higher stomatal density, while cabbages are the lowest in those parameters.


#8 Tank organisms of Ecuadorian cloud forest bromeliads

Megan E. Wilson1, Gregory K. Brown2, Scott R. Shaw1 and Timothy Collier1 1Department of Ecosystem Science and Management, Program in Ecology, University of Wyoming, Laramie, WY 2Department of Botany, University of Wyoming, Laramie, WY Abstract

Many bromeliads form phytotelmata, bodies of water held by plants, by overlapping leaf bases, providing habitats for invertebrates, including many insects. In this study, 40 bromeliads, primarily of two genera, were sampled from the Andean cloud forest in Napo Province, Ecuador. One hundred invertebrate morphospecies were identified; the most abundant groups sampled were Araneae and Coleoptera; however most morphospecies were represented by only one or two individuals. Relationships between bromeliad tank size and morphospecies richness and abundance were tested with multiple regression, showing that morphospecies richness and abundance were positively correlated with an increase in tank size.

#9 Did Native American fires maintain the longleaf pine ecosystem? A paleoecological approach

Rachel A. Jones and Stephen T. Jackson

Department of Botany, Program in Ecology, University of Wyoming, Laramie, WY Abstract

The longleaf pine savanna of the southeastern United States has been declining in areal extent during the past 300 years. Many factors contribute to this decline, including timber harvesting, land clearance and conversion. However, frequent surface fires are recognized as a primary factor in maintaining longleaf pine dominance. Missionary accounts from 16th century document that pre-‐Columbian populations in the southeast region used fire for agricultural and hunting purposes, suggesting that longleaf pine savannas were maintained by human-‐set fires. Regional Native American populations declined and societies collapsed during the 16th Century after introduction of diseases and military assaults by the deSoto Expedition and other European parties. We hypothesize that, if Native American cultural practices were responsible for maintaining the longleaf pine ecosystem, reduction of fires in the 16th and 17th Centuries should have led to invasion of longleaf pine stands by oaks and slash pines and conversion from savanna to forest. We are testing this hypothesis by examining pollen and charcoal records from lakes in the longleaf pine ecosystem.

We have obtained three lake sediment cores spanning the last 1000 years, one in north-‐central Florida (Sheelar Lake), one in central Florida (Leda’s Pond) and another in the Florida Peninsula (Silver Lake). #10 Understanding baseline and elevated urinary cortisol in a captive polar bear

John P. Whiteman1, Megan A. Owen2, Joanne Simerson3 1Dept of Zoology and Physiology, Program in Ecology, University of Wyoming, Laramie, WY 2Institute for Conservation Research, San Diego Zoo Global, San Diego, CA 3Joanne Simerson, Collections and Husbandry Science, San Diego Zoo, San Diego, CA Abstract

Glucocorticoids are a critical component of the stress response in animals, including the hormone cortisol in bears. Cortisol levels can be used as an index of stress when studying how bears respond to changes in the environment, and when making management decisions regarding captive animals. However, cortisol varies in circadian and circannual rhythms and is integral to many physiological processes. For example, cortisol


can stimulate or reduce feeding behavior, and enhance lipolysis through direct and indirect pathways – and reduced feeding and mobilization of stored fat are normal aspects of hibernation for many bear species. Thus, it is important to understand normal fluctuations in cortisol before relating cortisol levels to stress. We measured the ratio of cortisol to creatinine in urine samples collected from a female polar bear (aged 16 years at study initiation) over 22 consecutive months at the San Diego Zoo. This approach quantifies free cortisol (assumed to be more biologically active than bound cortisol) and corrects for fluctuating urine concentration. The bear was in a public exhibit (0.8 hectares) for the majority of the study with a male bear and his sister (both aged 11 years), but the bear was housed alone during the fall pregnancy watch. Throughout the study period we made daily observations of behavior and food consumption. In the first 12 months of sampling, high cortisol in winter (February/March) was generally associated with increased social interactions and breeding activity. Cortisol was low in spring, summer, and autumn; activity level and appetite were low throughout late summer and autumn, and body condition increased. A spike of high cortisol in late October was not associated with social or husbandry changes. In the subsequent 10 months of sampling, cortisol was high between February and May, spiking in April. In February, the female’s interactions and sexual behavior with the male began intensifying, peaking in late April and early May, when daily copulation was observed. Cortisol also spiked in July, August, and November. While there were no social or husbandry changes associated with these spikes, activity and appetite were low, and body condition increased. Preliminary analyses indicate that time of day does not strongly influence urinary cortisol. Pending analyses will increase sample sizes for testing for an effect of time of day, identifying seasonal peaks, and identifying potential correlations with social and husbandry changes.

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