Ecology
Permanent URI for this communityhttps://scholarworks.montana.edu/handle/1/44
The department's teaching and research addresses critical ecological and natural resources issues for Montana, but also tackles fundamental and applied questions around the globe.
Undergraduate programs within the department include Fish & Wildlife Management and Ecology, Conservation Biology and Ecology, Organismal Biology, and Biology Teaching. Graduate programs (M.S. and P.hD.) include Fish & Wildlife Management or Biology and Biological Sciences and an intercollege PhD in Ecology and Environmental Sciences.
Browse
199 results
Search Results
Item Comparing citizen science and professional data to evaluate extrapolated mountain goat distribution models(ESA, 2017-02) Flesch, Elizabeth; Belt, JamiCitizen science provides a prime opportunity for wildlife managers to obtain low-cost data recorded by volunteers to evaluate species distribution models and address research objectives. Using mountain goat (Oreamnos americanus) location data collected through aerial surveys by professionals, ground surveys by professionals, and ground surveys by volunteers, we evaluated two mountain goat distribution models extrapolated across Waterton-Glacier International Peace Park. In addition, we compared mountain goat location data by observer and survey type to determine whether there were differences that affected extrapolated model evaluation. We found that all dataset types compared similarly to both mountain goat models. A mountain goat occupancy model developed in the Greater Yellowstone Area (GYA) was the most informative in describing mountain goat locations. We compared Spearman-rank correlations (rs) for occupancy probability bin ranks in the GYA model extrapolation and area-adjusted frequencies of mountain goat locations, and we found that all datasets had a positive correlation, indicating the model had useful predictive ability. Aerial observations had a slightly greater Spearman-rank correlation (rs = 0.964), followed by the professional ground surveys (rs = 0.946), and volunteer ground datasets (rs = 0.898). These results suggest that with effective protocol development and volunteer training, biologists can use mountain goat location data collected by volunteers to evaluate extrapolated models. We recommend that future efforts should apply this approach to other wildlife species and explore development of wildlife distribution models using citizen science.Item Investigating old‐growth ponderosa pine physiology using tree‐rings, δ13C, δ18O, and a process‐based model(Wiley, 2019-06) Ulrich, Danielle E. M.; Still, Christopher; Brooks, J. Renée; Kim, Youngil; Meinzer, Frederick C.In dealing with predicted changes in environmental conditions outside those experienced today, forest managers and researchers rely on process‐based models to inform physiological processes and predict future forest growth responses. The carbon and oxygen isotope ratios of tree‐ring cellulose (δ13Ccell, δ18Ocell) reveal long‐term, integrated physiological responses to environmental conditions. We incorporated a submodel of δ18Ocell into the widely used Physiological Principles in Predicting Growth (3‐PG) model for the first time, to complement a recently added δ13Ccell submodel. We parameterized the model using previously reported stand characteristics and long‐term trajectories of tree‐ring growth, δ13Ccell, and δ18Ocell collected from the Metolius AmeriFlux site in central Oregon (upland trees). We then applied the parameterized model to a nearby set of riparian trees to investigate the physiological drivers of differences in observed basal area increment (BAI) and δ13Ccell trajectories between upland and riparian trees. The model showed that greater available soil water and maximum canopy conductance likely explain the greater observed BAI and lower δ13Ccell of riparian trees. Unexpectedly, both observed and simulated δ18Ocell trajectories did not differ between the upland and riparian trees, likely due to similar δ18O of source water isotope composition. The δ18Ocell submodel with a Peclet effect improved model estimates of δ18Ocell because its calculation utilizes 3‐PG growth and allocation processes. Because simulated stand‐level transpiration (E) is used in the δ18O submodel, aspects of leaf‐level anatomy such as the effective path length for transport of water from the xylem to the sites of evaporation could be estimated.Item Size-specific apparent survival rate estimates of white sharks using mark–recapture models(Canadian Science Publishing, 2019-02) Kanive, Paul E.; Rotella, Jay J.; Jorgensen, Salvador J.; Chapple, Taylor K.; HInes, James E.; Anderson, Scot D.; Block, Barbara A.Abstract: For species that exist at low abundance or are otherwise difficult to study, it is challenging to estimate vital rates such as survival and fecundity and common to assume that survival rates are constant across ages and sexes. Population assessments based on overly simplistic vital rates can lead to erroneous conclusions. We estimated sex- and length-based annual apparent survival rates for white sharks (Carcharodon carcharias). We found evidence that annual apparent survival differed over ontogeny in a system with competitive foraging aggregations, from 0.63 (standard error (SE) = 0.08) for newly recruiting subadults to 0.95 (SE = 0.02) for the largest sharks. Our results reveal a potential challenge to ontogenetic recruitment in a long-lived, highly mobile top marine predator, as survival rates for subadult white sharks may be lower than previously assumed. Alternatively, younger and competitively inferior individuals may be forced to permanently emigrate from primary foraging sites. This study provides new methodology for estimating apparent survival as a function of diverse covariates by capture–recapture study, including when sex assignment is uncertain. Résumé : Pour les espèces qui existent en faible abondance ou dont l’étude présente par ailleurs un défi, il est difficile d’estimer des indices vitaux comme la survie et la fécondité et il est couramment présumé que les taux de survie ne varient pas selon le sexe et le groupe d’âge. Des évaluations de populations reposant sur des indices vitaux trop simplistes peuvent mener à des conclusions erronées. Nous avons estimé les taux de survie annuels apparents en fonction du sexe et de la longueur pour de grands requins blancs (Carcharodon carcharias). Nous avons relevé des preuves de variation du taux de survie annuel apparent au fil de l’ontogénie dans un système caractérisé par des regroupements concurrents d’individus en quête de nourriture, ce taux allant de 0,63 (l’écart-type (ÉT) = 0,08) pour les individus subadultes récemment recrutés à 0,95 (ÉT = 0,02) pour les requins les plus grands. Nos résultats révèlent une difficulté potentielle en ce qui concerne le recrutement ontogénique chez un prédateur marin de niveau trophique supérieur très mobile et longévif, puisque les taux de survie de grands requins blancs subadultes pourraient être plus faibles que présumés auparavant. Une autre explication est que les individus plus jeunes ou moins concurrentiels pourraient être forcés d’émigrer des meilleurs sites d’approvisionnement de manière permanente. L’étude présente une nou-velle méthodologie pour estimer la survie apparente en fonction de différentes variables reliées, par une approche de capture–recapture, y compris pour les cas où l’affectation du sexe est incertaine. [Traduit par la Rédaction]Item Wildflower Seed Sales as Incentive for Adopting Flower Strips for Native Bee Conservation: A Cost-Benefit Analysis(2019-07) Delphia, Casey M.; O'Neill, Kevin M.; Burkle, Laura A.Improving pollinator habitat on farmlands is needed to further wild bee conservation and to sustain crop pollination in light of relationships between global declines in pollinators and reductions in floral resources. One management strategy gaining much attention is the use of wildflower strips planted alongside crops to provide supplemental floral resources for pollinators. However, farmer adoption of pollinator-friendly strategies has been minimal, likely due to uncertainty about costs and benefits of providing non-crop flowering plants for bees. Over 3 yr, on four diversified farms in Montana, United States, we estimated the potential economic profit of harvesting and selling wildflower seeds collected from flower strips implemented for wild bee conservation, as an incentive for farmers to adopt this management practice. We compared the potential profitability of selling small retail seed packets versus bulk wholesale seed. Our economic analyses indicated that potential revenue from retail seed sales exceeded the costs associated with establishing and maintaining wildflower strips after the second growing season. A wholesale approach, in contrast, resulted in considerable net economic losses. We provide proof-of-concept that, under retail scenarios, the sale of native wildflower seeds may provide an alternative economic benefit that, to our knowledge, remains unexplored. The retail seed-sales approach could encourage greater farmer adoption of wildflower strips as a pollinator-conservation strategy in agroecosystems. The approach could also fill a need for regionally produced, native wildflower seed for habitat restoration and landscaping aimed at conserving native plants and pollinators.Item High-severity wildfire limits available floral pollen quality and bumble bee nutrition compared to mixed-severity burns(2019-12) Simanonok, Michael P.; Burkle, Laura A.High-severity wildfires, which can homogenize floral communities, are becoming more common relative to historic mixed-severity fire regimes in the Northern Rockies of the U.S. High-severity wildfire could negatively affect bumble bees, which are typically diet generalists, if floral species of inadequate pollen quality dominate the landscape post-burn. High-severity wildfires often require more time to return to pre-burn vegetation composition, and thus, effects of high-severity burns may persist past initial impacts. We investigated how wildfire severity (mixed- vs. high-severity) and time-since-burn affected available floral pollen quality, corbicular pollen quality, and bumble bee nutrition using percent nitrogen as a proxy for pollen quality and bumble bee nutrition. We found that community-weighted mean floral pollen nitrogen, corbicular pollen nitrogen, and bumble bee nitrogen were greater on average by 0.82%N, 0.60%N, and 1.16%N, respectively, in mixed-severity burns. This pattern of enhanced floral pollen nitrogen in mixed-severity burns was likely driven by the floral community, as community-weighted mean floral pollen percent nitrogen explained 87.4% of deviance in floral community composition. Only bee percent nitrogen varied with time-since-burn, increasing by 0.33%N per year. If these patterns persist across systems, our findings suggest that although wildfire is an essential ecosystem process, there are negative early successional impacts of high-severity wildfires on bumble bees and potentially on other pollen-dependent organisms via reductions in available pollen quality and nutrition. This work examines a previously unexplored pathway for how disturbances can influence native bee success via altering the nutritional landscape of pollen.Item Carnivores, competition and genetic connectivity in the Anthropocene(2019-11) Creel, Scott; Spong, Goran; Becker, Matthew S.; Simukonda, Chuma; Norman, Anita; Schiffthaler, Bastian; Chifunte, CliveCurrent extinction rates are comparable to five prior mass extinctions in the earth’s history, and are strongly affected by human activities that have modified more than half of the earth’s terrestrial surface. Increasing human activity restricts animal movements and isolates formerly connected populations, a particular concern for the conservation of large carnivores, but no prior research has used high throughput sequencing in a standardized manner to examine genetic connectivity for multiple species of large carnivores and multiple ecosystems. Here, we used RAD SNP genotypes to test for differences in connectivity between multiple ecosystems for African wild dogs (Lycaon pictus) and lions (Panthera leo), and to test correlations between genetic distance, geographic distance and landscape resistance due to human activity. We found weaker connectivity, a stronger correlation between genetic distance and geographic distance, and a stronger correlation between genetic distance and landscape resistance for lions than for wild dogs, and propose a new hypothesis that adaptations to interspecific competition may help to explain differences in vulnerability to isolation by humans.Item Occupied and abandoned structures from ecosystem engineering differentially facilitate stream community colonization(2019-05) Tumolo, Benjamin B.; Albertson, Lindsey K.; Cross, Wyatt F.; Daniels, Melinda D.; Sklar, Leonard S.Ecosystem engineers transform habitats in ways that facilitate a diversity of species; however, few investigations have isolated short‐term effects of engineers from the longer‐term legacy effects of their engineered structures. We investigated how initial presence of net‐spinning caddisflies (Hydropsychidae) and their structures that provide and modify habitat differentially influence benthic community colonization in a headwater stream by conducting an in situ experiment that included three treatments: (1) initial engineering organism with its habitat modification structure occupied (hereafter caddisfly); (2) initial habitat modification structure alone (hereafter silk); and (3) a control with the initial absence of both engineer and habitat modification structure (hereafter control). Total invertebrate colonization density and biomass was higher in caddisfly and silk treatments compared to controls (~25% and 35%, respectively). However, finer‐scale patterns of taxonomy revealed that density for one of the taxa, Chironomidae, was ~19% higher in caddisfly compared to silk treatments. Additionally, conspecific biomass was higher by an average of 50% in silk treatments compared to controls; however, no differences in Hydropsyche sp. biomass were detected between caddisfly treatments and controls, indicating initially abandoned silk structures elevated conspecific biomass. These findings suggest that the positive effects of the habitat modification structures that were occupied for the entirety of the experiment may outweigh any potential negative impacts from the engineer, which is known to be territorial. Importantly, these results reveal that the initial presence of the engineer itself may be important in maintaining the ecological significance of habitat modifications. Furthermore, the habitat modifications that were initially abandoned (silk) had similar positive effects on conspecific biomass compared to caddisfly treatments, suggesting legacy effects of these engineering structures may have pertinent intraspecific feedbacks of the same magnitude to that of occupied habitat modifications. Elucidating how engineers and their habitat modifications differentially facilitate organisms will allow for a clearer mechanistic understanding of the extent to which animal engineers and their actions influence aspects of community organization such as colonization.Item Solitary bee life history traits and sex mediate responses to manipulated seasonal temperatures and season length(2019-08) Slominski, Anthony; Burkle, Laura A.The effects of climate change on solitary bee species, the most diverse and abundant group of wild pollinators, remain poorly understood, limiting our ability to forecast consequences for bee-plant interactions and pollination services. Life history traits, such as overwintering life stage, sex, and body size may influence solitary bee responses to climate change by mediating the effects of temperature on physiological processes spanning fall, winter, and spring. Yet, most studies assessing the effects of temperature on solitary bees have focused on managed species and have isolated the effects of winter temperature. Here, we reared male and female individuals representing eight cavity-nesting solitary bee species that overwinter either as adults (i.e., Osmia spp.) or prepupae (i.e., Megachile spp.). Eight rearing treatments were used, in which we manipulated fall and spring temperature, fall duration, and the timing of spring onset. We measured pre-emergence mortality, pre-emergence weight loss, emergence timing, and post-emergence lifespan. We found that Osmia spp. responded primarily to the timing of spring onset, whereas Megachile spp. responded primarily to spring temperature. Early-spring onset increased both pre-emergence mortality and pre-emergence weight loss and reduced post-emergence lifespan in Osmia spp. In addition, treatments caused unequal shifts in the timing of emergence between male and female Osmia spp. By contrast, warmer spring temperature decreased weight loss, and increased lifespan in Megachile spp. These findings suggest that Osmia spp. may be more vulnerable to negative fitness consequences of climate change compared to Megachile spp., and that climate change may have implications for population-level sex-ratios and mating success in species of Osmia. This work helps build a mechanistic understanding of how life histories may mediate solitary bee responses to climate change, and how these responses may impact solitary bee fitness and plant-bee interactions.Item Wildfires Influence Abundance, Diversity, and Intraspecific and Interspecific Trait Variation of Native Bees and Flowering Plants Across Burned and Unburned Landscapes(2019-07) Burkle, Laura A.; Simanonok, Michael P.; Durney, J. Simone; Myers, Jonathan; Belote, R. TravisWildfire regimes are changing in the western United States, yet the ways in which wildfires influence native bees, the resources they depend on for food and nesting, or the traits that influence their interactions with plants are poorly understood. In burned and unburned areas in Montana, USA, we investigated the abundance and diversity of native bees, floral and nesting resources, nesting success, and traits of flowers and bees. In two of the three localities studied, burned areas, including areas that burned with high-severity wildfires, supported higher density and diversity of native bees and the flowers they depend on for food and larval provisioning. Burned areas also had more bare ground for ground-nesting bees and more available coarse woody debris for cavity-nesting bees than unburned areas. Moreover, cavity-nesting bees were completely unsuccessful at nesting in artificial nesting boxes in unburned areas, while nesting success was 40% in burned areas. Mean bee intertegular distance (a trait strongly correlated with tongue length, foraging distance, and body size) was similar between burned and unburned areas. However, wildfires influenced both interspecific and intraspecific trait variation of bees and plants. Intraspecific variation in bee intertegular distance was higher in unburned than burned areas. Both interspecific and intraspecific variation in floral traits important for interactions with pollinators were generally higher in burned than unburned areas. Thus, wildfires generally increased the density and species diversity of bees and flowers as well as trait variation at both trophic levels. We conclude that wildfires—even large, high-severity wildfires—create conditions that support native bees and the resources they need to flourish, but that unburned areas maintain trait variation in landscape mosaics with heterogeneous fire conditions.Item Evaluating and presenting uncertainty in model‐based unconstrained ordination(2019-12) Hoegh, Andrew; Roberts, David W.Variability in ecological community composition is often analyzed by recording the presence or abundance of taxa in sample units, calculating a symmetric matrix of pairwise distances or dissimilarities among sample units and then mapping the resulting matrix to a low‐dimensional representation through methods collectively called ordination. Unconstrained ordination only uses taxon composition data, without any environmental or experimental covariates, to infer latent compositional gradients associated with the sampling units. Commonly, such distance‐based methods have been used for ordination, but recently there has been a shift toward model‐based approaches. Model‐based unconstrained ordinations are commonly formulated using a Bayesian latent factor model that permits uncertainty assessment for parameters, including the latent factors that correspond to gradients in community composition. While model‐based methods have the additional benefit of addressing uncertainty in the estimated gradients, typically the current practice is to report point estimates without summarizing uncertainty. To demonstrate the uncertainty present in model‐based unconstrained ordination, the well‐known spider and dune data sets were analyzed and shown to have large uncertainty in the ordination projections. Hence to understand the factors that contribute to the uncertainty, simulation studies were conducted to assess the impact of additional sampling units or species to help inform future ordination studies that seek to minimize variability in the latent factors. Accurate reporting of uncertainty is an important part of transparency in the scientific process; thus, a model‐based approach that accounts for uncertainty is valuable. An R package, UncertainOrd, contains visualization tools that accurately represent estimates of the gradients in community composition in the presence of uncertainty.