As land-use change threatens wildlife viability, the understanding of how animals move through spatially fragmented landscapes has important implications for the long-term persistence and management of species. This research compares moose movement and space-use patterns between Algonquin Provincial Park (20 moose) and Wildlife Management Unit 49 (17 moose) in southern Ontario from 2006 to 2008. Moose were found to be using areas in the home range that are not normally used more often in the park relative to the management unit, and that there are signs, although not significant, that the use of land covers between the two locations may be diverging. These differences are likely driven by the differences in predator and road densities between the two locations. I interpret these findings to suggest that Algonquin Provincial Park is protecting moose from the impacts of roads, but that moose can survive in the road-fragmented landscapes if there is enough habitat available.

Based on dental, cranial, and postcranial anatomy, members of the Permo-Carboniferous clade Diadectidae are generally regarded as the earliest tetrapods capable of processing high-fiber plant material; presented here is a review of diadectid morphology, phylogeny, taxonomy, and paleozoogeography. Phylogenetic analyses support the monophyly of Diadectidae within Diadectomorpha, the sister-group to Amniota, with Limnoscelis as the sister-taxon to Tseajaia + Diadectidae. Analysis of diadectid interrelationships of all known taxa for which adequate specimens and information are known—the first of its kind conducted—positions Ambedus pusillus as the sister-taxon to all other forms, with Diadectes sanmiguelensis, Orobates pabsti, Desmatodon hesperis, Diadectes absitus, and (Diadectes sideropelicus + Diadectes tenuitectes + Diasparactus zenos) representing progressively more derived taxa in a series of nested clades. In light of these results, it is recommended herein that the species Diadectes sanmiguelensis be referred to the new genus Oradectes, Diadectes absitus be referred to the new genus Silvadectes, and Diasparactus be synonymized with Diadectes to produce Diadectes zenos. The phylogenetic hypothesis also reveals an evolutionary history leading to more efficient oral processing within the lineage, with successive nodes characterized by features indicative of a high-fiber diet. Within Diadectomorpha, diadectids constitute the majority of the species, suggesting that the advent of herbivory resulted in a relatively rapid radiation of species within the group, producing a clade that is markedly more species-rich than other, non-herbivorous diadectomorph taxa. An extensive review of Permo-Carboniferous tetrapod-bearing localities does, however, indicate that diadectids were not a key component of the fauna, discovered at fewer than 50 percent of the sites reviewed. These results counter suggestions that the evolution of Diadectidae led to the formation of the modern terrestrial ecosystem—where a large crop of herbivores supports a much smaller number of carnivores—during the Late Carboniferous and Early Permian.

Master of Science / Division of Biology / Walter K. Dodds / Understanding the variability of ecological processes across spatial scales is a central issue in ecology, because increasing scale is often associated with increasing complexity. In streams, measurements of biogeochemical fluxes are important for determining ecosystem health and the downstream delivery of nutrients, but are often collected at scales with benthic areas measured in spatial areas from ~10 cm[superscript]2 to ~100 m[superscript]2 (referred to here as patch and reach, respectively), which are smaller than the scale that management decisions are made. Both biotic and abiotic factors will be important when attempting to predict (i.e. scale) biogeochemical rates, but few studies have simultaneously measured rates and their primary drivers at different spatial scales. In the first chapter, I used a conceptual scaling framework to evaluate the ability to additively scale biogeochemical rates by comparing measurements of ecosystem respiration (ER) and gross primary production (GPP) from patch to reach-scales across multiple sites over a two-year period in a prairie stream. Patch-scale measurements with and without fish (biotic factors) and abiotic factors measured simultaneously with metabolic rates suggest that abiotic conditions are stronger drivers of these rates. Patch-scale rates significantly overestimated reach rates for ER and GPP after corrections for habitat heterogeneity, temperature and light, and a variety of stream substrata compartments. I show the importance of determining abiotic and biotic drivers, which can be determined through observational or experimental measurements, when building models for scaling biogeochemical rates. In the second chapter, I further examined patch-scale abiotic and biotic drivers of multiple biogeochemical rates (ER, GPP, and ammonium uptake) using path analyses and data from chapter 2. Total model-explained variance was highest for ER (65% as R[superscript]2) and lowest for GPP and ammonium uptake (38%). Fish removal directly increased ammonium uptake, while all rates were indirectly affected by fish removal through changes in either FBOM and /or algal biomass. Significant paths of abiotic factors varied with each model. Large-scale processes (i.e. climate change and direct anthropogenic disturbances), and local biotic and abiotic drivers should all be considered when attempting to predict stream biogeochemical fluxes at varying spatial scales.

Doctor of Philosophy / Department of Biology / Jack F. Cully, Jr. / Black-tailed prairie dogs (Cynomys ludovicianus) are epizootic hosts for plague (Yersinia pestis); however, alternate enzootic hosts are important for the maintenance of the pathogen. We determined small rodents and prairie dog associations and quantified rodent and flea relationships in the presence and absence of prairie dog colonies and plague. We identified potential alternate hosts and flea vectors for the maintenance and transmission of plague in the prairie ecosystem. This is the first multi-year study to investigate associations between prairie dogs, rodents and fleas across the range of the black-tailed prairie dog. Few rodent species associated with black-tailed prairie dogs and were found to be highly abundant on colonies. Rodent species implicated in plague were present at study areas with and without plague. Peromyscus maniculatus and Onychomus leucogaster, two widely occurring species, were more abundant in areas with a recent history of plague. Flea community characteristics varied within each study area in the presence and absence of prairie dogs. Based on flea diversity on rodents, and the role of rodents and fleas in plague, we identified P. maniculatus and O. leucogaster and their associated fleas, Aetheca wagneri, Malareus telchinus, Orchopeas leucopus, Peromyscopsylla hesperomys, and Pleochaetis exilis to be important for the dynamics of sylvatic plague in our study areas. Peromyscus maniculatus and O. leucogaster were consistently infected with Bartonella spp., another blood parasite. Presence of prairie dog fleas on other rodents at both off and on prairie dog colonies suggests the potential for intra and interspecific transmission of fleas between rodent hosts, and between other small rodents and prairie dogs.

Doctor of Philosophy / Department of Biology / David C. Hartnett / In perennial grasslands, the belowground population of meristems (the bud bank) plays a fundamental role in local plant population structure and dynamics. I tested the “meristem limitation hypothesis” prediction that bud banks increase along an increasing precipitation/productivity gradient in North American grasslands. I sampled bud populations quarterly at six sites across a 1,100 km gradient in central North America. Bud banks increased with average annual precipitation, which explained 80% of variability in bud banks among sites. Seasonal changes in grass bud banks were surprisingly similar across a 2.5-fold range in precipitation and a 4-fold range of aboveground net primary productivity (ANPP). Secondly, I tested the hypothesis that tallgrass prairie plants respond to increases in a limiting resource (nitrogen) through demographic effects on the bud bank. I parameterized matrix models for individual genets, considering each genet as a population of plant parts (buds and stems). Nitrogen addition significantly impacted bud bank demography of both Sporobolus heterolepis and Koeleria macrantha. In 2005, emergence from the bud bank and growth rates (λ) of the tiller population were significantly higher in S. heterolepis genets that received nitrogen. In contrast, nitrogen addition decreased λ in K. macrantha. Both prospective and retrospective analyses indicated that bud bank dynamics are the key demographic processes driving genet responses to nutrient availability. Lastly, I tested the hypothesis that the effects of fire and grazing on plant species composition and ANPP are mediated principally through demographic effects on bud banks. I found that plants respond to fire and grazing with altered rates of belowground bud natality, bud emergence, and both short-term (fire cycle) and long-term changes in bud density. The size of the bud bank is an excellent predictor of long-term ANPP, supporting my hypothesis that ANPP is strongly regulated by belowground demographic processes. Meristem limitation due to water or nutrient availability or management practices such as fire and grazing may constrain grassland responses to inter-annual changes in resource availability. An important consequence is that grasslands with a large bud bank may be the most responsive to future climatic change or other phenomena such as nutrient enrichment, and may be most resistant to exotic species invasions.

Master of Science / Department of Biology / Brett K. Sandercock / Translocations are a useful management tool for restoring wildlife species to their native ranges, but require post-release monitoring to determine project success. We report results of a 4-year effort to reestablish a breeding population of Evermann's Rock Ptarmigan (Lagopus mutus evermanni) on Agattu Island in the Aleutian Archipelago, Alaska. This endemic subspecies of ptarmigan was extirpated from most of the Near Islands by introductions of arctic fox by fur traders, and natural recolonizations did not occur after fox eradication. All females surviving the 2-week post-release period attempted to nest but initiated clutches later in the season and laid fewer eggs than resident females. Nest success was similar for resident and translocated females. Brood survival was greater for translocated than resident females and differed significantly; however, brood survival varied among years and was reduced by adverse weather conditions in 2006. Seasonal survival of radio-marked birds during the breeding season was 100% for translocated and resident ptarmigan. Over-winter mortality resulted in a low return rate in 2006. Returning birds in 2006 showed strong site fidelity and nest locations in two consecutive years were closely spaced. We examined nest site selection and determined brood movements and home range size of recently translocated and resident females. Nest sites of translocated females averaged 4.2 km from their respective release location and were not different from nest locations of resident females with regard to topographical features. Female nest site selection was influenced by percent composition of rock and forb coverage but was unaffected by slope, aspect, or general habitat. Broods of both resident and translocated females made movements to higher elevations after hatching. While size of brood home range was similar for resident and translocated females, distances traveled between the nest site and the arithmetic center of the brood home range were greater for translocated females. Overall, we conclude that translocations are an effective technique for reestablishing island populations of Rock Ptarmigan. Our study provides successful methods which may benefit future projects to reestablish endemic populations of ptarmigan and landbirds elsewhere in the Aleutian Islands.

Master of Science / Department of Biology / David C. Hartnett / Herbivory is one of the major biotic interactions shaping the structure and dynamics of grassland plant populations and community structure. The two major grass growth forms, rhizomatous and caespitose species, may show different grazing tolerance and short-term overcompensation may offset long-term reductions in plant performance and fitness. The objectives of this study were to assess 1) the effects of long-term ungulate grazing on plant architecture, population structure, and life history traits of the caespitose perennial grass, Schizachyrium scoparium (little bluestem), and the rhizomatous Bouteloua curtipendula (sideoats grama) in tallgrass prairie, and 2) the effects of grazing intensity (frequency of defoliation) on growth responses of little bluestem. Long-term bison grazing decreased the cover, frequency, tiller height, and proportion of tillers producing seed in little bluestem, but caused no changes in tiller density and total genet size. Grazed little bluestem plants maintained a significantly larger below ground bud bank. Bison grazing had no long-term effect on the abundance, bud bank densities, or rhizome growth of the rhizomatous side-oats grama grass. Biomass, tiller density, relative growth rates, and proportion of tillers flowering in little bluestem all decreased with increasing frequency of defoliation. However, even an intense grazing regime (9 defoliations over a 12 month period) caused no plant mortality and no changes in new tiller emergence rates, or bud bank densities. Increasing defoliation frequency did result in shifts in plant architecture, as an increasing proportion of extravaginal tillers led to a more lateral, decumbent growth form. These results show that the rhizomatous side-oats grama grass has a significantly higher grazing tolerance than does little bluestem, and/or that bison selectively graze little bluestem. Results from responses to the experimental defoliation regimes suggest that little bluestem shows lower tolerance to high frequency of defoliation, and its maintenance of a reserve below ground bud bank may be its primary tolerance mechanism, allowing tiller populations to recover following severe defoliation.

Doctor of Philosophy / Department of Biology / Anthony Joern / Aboveground and belowground food webs are linked by plants, but their reciprocal influences are seldom studied. Because phosphorus (P) is the primary nutrient associated with arbuscular mycorrhizal (AM) symbiosis, and evidence suggests it may be more limiting than nitrogen (N) for some insect herbivores, assessing carbon (C):N:P stoichiometry will enhance my ability to discern trophic interactions. The objective of this research was to investigate functional linkages between aboveground and belowground invertebrate populations and communities and to identify potential mechanisms regulating these interactions using a C:N:P stoichiometric framework. Specifically, I examine (1) long-term grasshopper community responses to three large-scale drivers of grassland ecosystem dynamics, (2) food selection by the mixed-feeding grasshopper Melanoplus bivittatus, (3) the mechanisms for nutrient regulation by M. bivittatus, (4) food selection by fungivorous Collembola, and (5) the effects of C:N:P on invertebrate community composition and aboveground-belowground food web linkages. In my analysis of grasshopper community responses to fire, bison grazing, and weather over 25 years, I found that all three drivers affected grasshopper community dynamics, most likely acting indirectly through effects on plant community structure, composition and nutritional quality. In a field study, the diet of M. bivittatus was dominated by forbs with grasses constituting only a minor fraction of their diet under ambient soil conditions, but grass consumption approximately doubled as a result of changes in grass C:N:P. M. bivittatus was found to rely primarily on selective consumption of foods with varying nutritional quality, rather than compensatory feeding or altering post-ingestive processes, to maintain C:N homeostasis in a laboratory experiment. In a soil-based mesocosm study, I show that Collembola feed on both saprophytic and AM fungi, in some cases exhibiting a slight preference for AM fungi. In the final study, although I did not find the expected indirect relationship between soil Collembola and aboveground herbivory as mediated through host plant quality, there were significant effects of root C:N and AM colonization on Collembola density and of plant C:N on aboveground herbivory. Overall, this research shows that host plant C:N:P stoichiometry can influence both above- and belowground invertebrate population, community, and food web dynamics.

Master of Science / Department of Biology / Keith B. Gido / Stream networks provide complex habitats for fish assemblages that can vary gradually along a gradient of stream size or abruptly at transition zones between large rivers and their tributaries. We evaluated the relative importance of these gradual and abrupt habitat transitions in regulating stream fish assemblages by quantifying roles of stream size and spatial position within a drainage network as a determinant of fish assemblage structure within the Kansas River basin, KS. We predicted fish assemblage structure to generally be dependent on stream size and that smaller streams would be influenced by their connectance to larger mainstem rivers. Fishes in the Kansas River basin varied along a gradient of stream size and longitude, and after controlling for these effects, there was evidence that connectivity to a larger river influenced species richness and assemblage structure. In 1st order streams there was an increase in species richness with increasing distance from a mainstem confluence and species composition in larger tributaries (i.e., 4th order streams) varied with proximity to the mainstem river. We also found an increase in species richness at sites located on smaller tributaries connected to a larger downstream mainstem. Species composition in 1st and 4th order streams also varied with connectance to the mainstem river. Within three intensively sampled tributaries, there was an abrupt change in fish fauna between the Kansas River and sample sites above the confluence, but only gradual change in assemblage structure within each tributary with a high degree of seasonal variation. In the first 20 stream km of these three mainstem tributaries adult fishes were more structured along a gradient away from the mainstem river than juveniles, potentially suggesting more generalized habitat needs of juvenile fishes. At the spatial and temporal scale of our analysis, it appeared the effects of large rivers on tributary streams were generally localized. However, the documented influence of spatial position suggests movements between habitats could regulate community level dynamics as well as individual species over longer temporal scales.

Master of Science / Department of Biology / Brett K. Sandercock / Monitoring programs indicate that numerous shorebird populations are subject to on-going declines. The U.S. Shorebird Conservation Plan lists twenty-seven shorebird species as species of high concern and seven as highly imperiled, including the Buff-breasted Sandpiper (Tryngites subruficollis). One hypothesis for ongoing population declines is exposure to toxic chemicals and pollutants. The purpose of this project was to characterize plasma cholinesterases (ChEs) of migratory shorebirds and address potential exposure to organophosphorus (OP) and carbamate (CB) pesticides. Consumption or contact with these pesticides can cause mortality and a variety of sub-lethal effects. Buff-breasted Sandpipers and other upland shorebirds are particularly likely to encounter agrochemicals due to their habitat use at the non-breeding grounds. I sampled migratory shorebirds over three seasons, during north- and southbound migration in 2006 and 2007 in Texas, Kansas, and Nebraska and during the non-breeding season in 2007 in Argentina, Uruguay, and Paraguay. I collected blood samples and footwashings from reference sites, where OP and CB pesticides were not used, and agricultural sites, where these two insecticides were recommended for control of crop pests. I assessed several variables known to affect plasma ChE activity including body size, date of capture, time of capture, condition, sex, and region. Small-bodied species had higher levels of ChE activity in plasma than large-bodied species. Plasma ChE activities varied with date of capture in 3 of 5 species sampled in North America. Sex differences were significant in 1 of 4 species tested. Plasma acetylcholinesterase (AChE) activity was higher among White-rumped Sandpipers sampled in North America but there was no difference between regions among Buff-breasted Sandpipers. Time of capture and individual condition did not affect plasma ChE activity. Estimates of exposure to ChE inhibitors were addressed in five species. Plasma AChE and butyrylcholinesterase (BChE) activities of Buff-breasted Sandpipers were lower at agricultural sites in South America but BChE activity was higher at agricultural sites in North America. There were no differences between sites in four other species tested. A meta-analysis across all species indicated that in 4 of 6 comparisons habitat type had a negative effect on AChE activity consistent with exposure to ChE inhibitors but there was a regional positive effect of agricultural habitat on BChE activity in North America. Comparison of body mass between sites suggested that use of habitats with potential pesticide application did not affect mass gain. Project results suggest that 1 of 5 shorebird species tested was exposed to ChE-inhibiting pesticides at the non-breeding grounds and future monitoring is necessary to assess potential effects at the population level. This study highlights the importance of complete sampling and addressing variability in plasma ChEs before making estimates of exposure to OP and CB pesticides. It provides the first estimates of migratory shorebird exposure to OP and CB pesticides, a potential conservation issue. Future research should include continued monitoring of Buff-breasted Sandpiper ChE levels and habitat use. Other sources of anthropogenic declines such as habitat loss and illegal hunting should be investigated for species that did not show evidence of exposure.