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Organisms live in heterogeneous environments but fail to demonstrate optimal adaptation toil the totality of the ecological conditions they experience. This imperfection would result from trade-offs between ecologically relevant traits, which implies that trade-offs are the ultimate cause of major features of life such as biodiversity. Here, I selected bacterial populations in defined laboratory environments to test for the importance of differences in productivity and quality among alternative resources (Chapter 1), as well as the spatial pattern of resources (Chapter 2), in shaping the evolution of ecological niches and genetic diversity. The experiment presented in Chapter 1 provides support for a general model for the evolution of diversity. In Chapter 2 however, I suggest that mutational processes can impinge on the expression of trade-offs, which is not recognized in our current view of the problem of diversity. These findings provide plausible explanations for situations where expected trade-offs are not found.

A high temporal resolution pollen diagram from a lake in the middle-Arctic region of the Boothia Peninsula, Nunavut, Canada, documents the history of the regional vegetation and climate for the past 7200 years. A diatom sequence had been previously prepared from this core. Major tundra pollen taxa in the core include Cyperaceae and Salix, with Cyperaceae comprising over 50% of the pollen in the early and late Holocene. Tree pollen, transported from far to the south, comprised a large percentage of the pollen sum, with Pinus accounting for 30% of the pollen in some levels of the core. Pollen percentages and concentrations of taxa typical of the middle-Arctic were highest in the mid-Holocene, corresponding to warm conditions. Decreasing pollen concentrations indicate cooling temperatures, with more rapid decreases occurring around 4200, 3800-3400, and 2500 cal yr BP. Pollen percentages of Salix, Cyperaceae, and Artemisia increased in the past 35 years in response to global warming. Reconstructions of July temperature using the modern analog technique showed the mid-Holocene (5800-2800 cal yr BP) was approximately 1°C higher than during the past 1000 years.

Contemporary and Phanerozoic Patterns of Global Biodiversity is a global study testing theories explaining variation in taxic richness, and drawing parallels between contemporary- and paleodiversity. The unifying idea of the thesis is that most of the variation in contemporary and past richness depends on analogous factors: (1) sampling effects, (2) richness-energy relationships, and (3) geometric considerations pertaining to isolation and fragmentation. We present a predictive model of global island biogeography, uniting classic ideas of the Equilibrium Theory of Island Biogeography (ETIB) with the Species-Energy Theory (Chapter 1). We quantify insular isolation and propose an equation to measure the isolation reducing effects of neighboring islands. In Chapter 2 we extend our model to continental parcels of land. We show that area-climate interactions are strong both on continents and on islands. Notwithstanding, species-area slopes do not depend either on distance-based or on historical isolation, in apparent contradiction with some predictions of the ETIB. Thus, broad-scale patterns of diversity on islands and continents are commensurable. In Chapter 3 we evaluate the completeness of the global Phanerozoic record of continental (terrestrial and freshwater) metazoans, aiming to use these data in subsequent chapters. Results of this analysis suggest the relative completeness of the continental fossil record is not markedly inferior to that of the marine fossil record at the taxonomic level of the family and at the stratigraphic level of the stage. The exponential diversification curve of suprageneric continental taxa is unlikely to be the result of rock bias. Chapter 4 adopts a multivariate approach to model variation in fossil diversity. Our main finding is that turnovers of metazoan families are strongly correlated with the number of magnetic polarity reversal records per stratigraphic stage over the Phanerozoic. This suggests that either variation in fossil richness and reversal intensity are both strongly influenced by preservation bias, or that extinction and origination rates have a strong and quantifiable perturbation regime. In Chapter 5 we classify stratigraphic stages into alternating extinction and origination cycles to test for supercyclicity. Paleomagnetic and fossil data both support this hypothesis over the Lower Paleozoic, the Upper Paleozoic and the Mesozoic.

Trilobites typical of the well known Olenellus zone of the Lower Cambrian constitute a large collection from the Eager Formation, near Cranbrook, B.C. Their classification is discussed and two new species described: Olenellus eagerensis n.sp. and Olenellus schofieldi n.sp. Since the use of certain structures in classifying olenellids has been disputed in the past, these and other less controversial features are critically examined, insofar as they apply to the genera and species present. From this study the writer assembles criteria which might be used by later workers to redefine the generic and specific positions of selected species of Olenellus and Paedeumias. / Arts, Faculty of / Geography, Department of / Graduate

Both fossil and living foraminifera have been investigated in this study. Late Cretaceous age foraminiferal assemblages have been used to examine the relationship between high-frequency sea level change, biotic response and paleoceanography, in the U.S. Western Interior Sea. Living planktic foraminifera were also studied in order to test a novel hypothesis on the evolution of cellular organelles known as fibrillar bodies. The major findings of this dissertation are: (1) The third-order Greenhorn tectono-eustatic cycle (late Cenomanian-middle Turonian) in the Cretaceous Western Interior Basin is superposed by fourth-order relative sea level cycles and fifth-order parasequences that are reflected in foraminferal assemblages and carbonate content of shales and mudrocks. The study interval includes the Cenomanian/Turonian (C/T) boundary event (93.3 Ma) and the highest stand of sea level in the western interior during early Turonian time. Calcareous benthic foraminiferal assemblages show marked shifts in taxon dominance which is interpreted as ecologic replacement indicating change from a food-controlled to an oxygen-controlled environment. Acmes of the genus Gavelinella are related to the initiation of fourth-order transgressive episodes early in the third-order transgression and late highstand phases of the Greenhorn Cycle. The rapid proliferation of this taxon is thought to be a response to pulses of food. Warm, oxygen-poor Tethyan waters spread across the WIS during the late transgression and highstand phases of the Greenhorn Cycle. A rapid ecologic shift to Neobulimina dominance is the benthic foraminiferal response to this Tethyan incursion. The relative abundance of Neobulimina shows a highly significant correlation to carbonate content (p $<$ 0.01), which is a proxy for warm, more normal marine water masses entering the WIS from the south. Tethyan water masses were replaced by those of Boreal affinity and agglutinated benthic foraminiferal assemblages during the regressive phase of the Greenhorn Cycle. Variations in benthic foraminiferal assemblage composition mirror changes in water mass salinity, oxygenation, circulation and productivity. Foraminiferal data from the western margin of the WIS support GCM models of estuarine circulation. (2) Fibrillar bodies are organelles present in the cytoplasm of all planktic foraminifera. I propose that they may have originated as symbiotic bacteria. Those in Pulleniatina obliquiloculata are squat to elongate ovoids and elongate rods with a length of 2-15 $\mu$m and a diameter of 2-5 $\mu$m. One, sometimes two such bodies (possibly products of binary fission) are bounded by a membrane-like vacuolar structure. They have an electron-lucent (DNA-containing?) central region, ribosome-like and storage-like granules, and are commonly enclosed within a vacuole. (Abstract shortened by UMI.)

The record of the changing composition of planktonic foraminifer assemblages constitutes a record of changes in the hydrography of the upper water column. A priori knowledge of the ecology and paleoecology of prominent taxa is used to interpret past changes in the hydrography of the upper water column, particularly the position of the seasonal thermocline. In this study planktonic foraminifers have been counted at five sites in the equatorial Pacific (ODP Site 806, 807, 847 and 852) and Atlantic (ODP Site 925). The initial sampling interval at all sites is $\sim$9.5 m ($\sim$250 kyr) through approximately the last 6 m.y. In the first paper the results of low-resolution faunal counts of four sites are presented in the depth domain. In the upper Miocene both eastern and western samples contained 60% thermocline dwellers and 40% mixed-layer dwellers. At the western sites the mixed-layer dwellers increase until they constitute 80% of the assemblage in the Pleistocene. At ODP Site 847 thermocline dwellers increase in the Pleistocene to comprise $>$80% of the assemblage. In the second paper data from ODP Sites 806 and 847 was placed in the time domain and higher-resolution sampling ($\sim$20 cm = $\sim$10 kyr) was carried out through two intervals (4.35-4.10 Ma and 3.15-2.90 Ma). The disappearance of thermocline-dwelling Neogene globoturborotalitids at ODP Site 806 coincides with the reduction of late Miocene Antarctic ice volume and southeast tradewind strength, the end of the biogenic bloom in the Pacific and the beginning of the closing of the Central American Seaway. The expansion of thermocline dweller Neogloboquadrina dutertrei at ODP Site 847 follows the onset of large-scale Northern Hemisphere glaciaton. The third paper explores the relationship between isotopic data for three species (Globigerinoides sacculifer, Neogloboquadrina dutertrei and Globorotalia crassaformis) and faunal count data. Assemblage composition at ODP Site 925 is principally affected by the intensity of downwelling associated with the ITCZ, which moves steadily equatorward from the early Pliocene to the early Pleistocene due to the cooling of the Northern relative to the Southern Hemisphere.

Microwear analysis has been severely underutilized as a dietary technique due to numerous constraints involved in employing traditional scanning electron microscopy. A new methodology is described that greatly simplifies the assessment of microwear scar features for the discernment of the trophic adaptations of living and fossil taxa. A standard stereomicroscope and a fiber-optic light source have replaced specimen preparation tools such as venting and plating apparatus and the high-tech scanning electron microscope. Several new microwear variables supplement traditional quantification of pits and scratches. Significant niche partitioning in extant browsers, grazers, and mixed feeders is apparent and habitat differences within each broad trophic group are discernible by scoring relative pit sizes, scratch textures, and gouges in addition to quantifying scratches and pits. Variations in scratch number ranges, scratch textures, and relative pit sizes are the most useful variables for partitioning living ungulates into more refined trophic categories. Pit numbers and scratch textures are most effective for distinguishing fine versus coarse browsing, as well as leaf browsing versus fruit browsing. Scratch textural differences and scratch numbers distinguish fresh grass grazing versus coarse or mixed grass grazing; C3 versus C4 grazing, coarse bark and stem feeding, and seasonal or regional mixed feeding versus a meal-by-meal alternation between browse and grass. Heavy gouging is used to distinguish significant grit encroachment upon food items. Seasonal or regional mixed feeders have microwear that is more similar to browsers, whereas meal-by-meal mixed feeders have wear more similar to grazers. Three trophic phases are identified within extant ungulates by partitioning taxa into three potential raw scratch ranges: traditional browsing and grazing phases, comprised by surprisingly few species, and a browsing-to-grazing transitional phase where the majority of taxa are found, including all of the mixed feeders. The new microwear methodology is used to test two hypotheses regarding large shifts in dietary strategies in fossil ungulates from the North American Great Plains region: the supposed browsing-grazing transition in the fossil record of North American equids and the supposed shift to coarser browse in the fossil ruminant artiodactyl family known as the Dromomerycidae.

The biodiversity and biomass of coccolithophore species observed in the NE Gulf of Mexico during the months of August through November from 2011 to 2013 are quite dynamic. Following the Macondo well blow out in 2010, analyses have been carried out on samples taken during the subsequent three years in the photic zone at 28 sites along four transects across the continental shelf and slope to observe ecological patterns in the calcareous nannoplankton assemblages. By extracting living cells from water samples collected via a CTD rosette and analyzing individual cell counts to identify specific species types and abundances, I have traced the vertical and horizontal distribution of these taxa over the 3-year interval. The number of observed species increases from station to station as one moves from shallow waters across the continental shelf into deeper waters. This is due to a two water-layer configuration observed during August to November. As one moves into deeper waters the salinity, temperature and amount of light penetration begin to change, which is useful in tracing the thermocline and distinguishing the two layers. Once the depth exceeds 75 meters a new assemblage of deeper photic-zone dwellers consisting of oligotrophic species can be observed. Therefore, two separate nannoplankton assemblages can be observed, the top in the mixed layer from the surface to 75 meters depth, and the lower oligotrophic assemblages below the thermocline from 75 meters to the lower limits of the photic zone, which for the Gulf of Mexico is 200 meters. A comparison of site biodiversity and biomass across stations during the study period also shows an increase in both cell density and number of species observed for each successive year sampled. The lowest cell-per-liter and species diversity is observed in 2011 with increasing numbers in 2012 and the highest recorded in 2013. Shifts in temperature and salinity recorded via the CTD are provided along with florescence profiles help us understand species distributions. I also noted a species, Navilithus altivelum, previously unknown in the Gulf of Mexico and the western hemisphere. This observation shows how rare and diverse these oligotrophic species can be as well as how important it is to conduct long-term census work. / A Thesis submitted to the Department of Earth, Ocean, and Atmospheric Sciences in partial fulfillment of the requirements for the degree of Master of Science. / Spring Semester, 2015. / December 12, 2014. / altivelum, nannoplankton, navilithus, phyotplankton, plankton, profunda / Includes bibliographical references. / Sherwood W. Wise, Jr., Professor Directing Thesis; Yang Wang, Committee Member; William Parker, Committee Member.

This dissertation presents biostratigraphic, taxonomic and paleoceanographic studies of sediment cores from low-latitude Ocean Drilling Program (ODP) Legs 154 (Site 929), 115 (Site 709), and 202 (Site 1237). Three major paleoceanographic events are featured: 1) the Oi-glacial events in the early-late Oligocene, 2) the Late Oligocene Warming Event (LOWE), and 3) the Oligocene/Miocene Boundary and Mi-1 glacial event. In Chapter Two, a new modified calcareous nannofossil zonation is proposed for the low latitudes that is composed of five major zones and three subzones between 24-30 Ma in age. The first occurrences of Sphenolithus avis, S. ciperoensis, Crassidiscus backmanii along with an increase in abundance of S. ciperoensis, and the last occurrences of S. predistentus, Crassidiscus backmanii and S. ciperoensis are synchronous and reliable throughout the tropics. The last occurrences of Sphenolithus distentus and S. avis are considered unreliable events due to a possible reworking of the former taxon and a diachronous occurrence of the latter. The last occurrences of Helicosphaera compacta and S. pseudoradians are only found in two out of three basins and thus are used as secondary events. The spatial and temporal distributions of calcareous nannofossil assemblages show major variations within the three tropical/subtropical sites. Sphenolithus taxa were found in low abundances in the Atlantic Ocean. Weak tolerance to low salinity is proposed since salinity declined in the Atlantic Ocean during the late Oligocene glacial events due to episodes of freshwater and terrigenous discharge from the Amazon River. This also lowered the δ18O values of seawater at Site 929 compared with the other sites. Furthermore, Site 929 was not far from its present-day position near the mouth of the Amazon River, thus, the low salinity levels best explains the observed major decline in Sphenolithus taxa. Calcareous nannofossil relative abundances (%) and bulk oxygen and carbon stable isotope data reveal a covariant response to glacial (Oi) events. During glacial events, temperate-, cool-water and eutrophic taxa dominated the tropical assemblage, whereas warm and oligotrophic taxa declined. This increase in temperate and cool-water taxa suggest that the tropical surface oceans witnessed a decrease in temperature that allowed cool-, and temperate-water taxa to extend their geographic range into the tropical zone. The Oligocene global glacial events (Oi-2*, Oi-2a, Oi-2b, and Oi-2c) were associated with accelerated upwelling in which eutrophic conditions prevailed and r-mode taxa dominated the total nannofossil abundance. Both Sphenolithus predistentus and Helicosphaera species show prominent increases during glacial (Oi) events. Unlike other Sphenolithus taxa that favored high salinity, S. predistentus increased in abundance during glacial events characterized by high δ18O and δ13C values. Similarly, Helicosphaera taxa show the same pattern with sporadic occurrences. This suggests that S. predistentus and Helicosphaera species were adapted to increased levels of nutrient (eutrophic or mesotrophic). Between 24-25 Ma, warm and oligotrophic taxa increased drastically and dominated the overall assemblage. However, bulk sediment δ18O and δ13C values at the three sites do not show a consistent decreasing trend similar to the global composite deep-sea isotopic record. Although the paleoecological group suggests oligotrophic conditions associated with dominate warm water, the paleotemperature of the sea surface during the LOWE was not as warm as during the Eocene hyperthermals. In Chapter Three, a new and significant late Oligocene Sphenolithus species is described from the tropical ODP materials. The new species, Sphenolithus avis, has a prominent short range spanning upper Zone NP23 to upper Zone NP25 with an age from ~29.9 Ma to 24.8 Ma. Sphenolithus avis is widely distributed and it differs from S. ciperoensis by more flaring proximal shields. In Chapter Four, high-resolution Oligocene/Miocene calcareous nannofossil biostratigraphy has revealed thirteen events, five of which are reliable and synchronous due to their similar ages in the Indian and Pacific Oceans. The synchronous events are: the last occurrences (LOs) of C. fenestratus and S. delphix, and first occurrence (FO) of S. disbelemnos and the beginning and ending of the S. conicus acme. The Sphenolithus conicus acme is documented in the Indian Ocean between 23.5 Ma and 22.8 Ma. This acme was first found in the Pacific Ocean across the Mi-1 glacial event which is characterized by high δ18O and δ13C values. This study supports a correlation of the S. conicus acme in the Indian Ocean with that of relatively similar age in the Pacific Ocean. / A Dissertation submitted to the Department of Earth, Ocean, and Atmospheric Sciences in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Spring Semester 2016. / April 15, 2016. / Biostratigraphy, Calcareous Nannofossils, Glacial events, Oligocene, Paleoecology, Taxonomy / Includes bibliographical references. / Sherwood W. Wise, Jr., Professor Directing Dissertation; Laura R. Keller, University Representative; William C. Parker, Committee Member; Yang Wang, Committee Member.