Browsing by Author "Theodor, Jessica M."
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Item Open Access A reassessment of protoceratid vertebrarterial canal morphology(Taylor and Francis, 2022-08-31) Robson, Selina Viktor; Theodor, Jessica M.The Protoceratidae are a family of extinct artiodactyls that have been variably allied with camelids and ruminants. One of the few synapomorphies uniting protoceratids and camelids is their unusual vertebrarterial canal morphology; the canal passes through the cervical vertebrae at an oblique angle rather than through the bases of the transverse processes. This unusual morphology has been upheld as a key piece of evidence for a close relationship between the two families. Upon reviewing the literature and examining specimens of three protoceratid genera, we have determined that protoceratids do not share a vertebrarterial canal morphology with camelids. Indeed, the vertebrarterial canal of protoceratids passes through the bases of the transverse processes, the condition found in most artiodactyls. This eliminates the only synapomorphy uniting protoceratids and camelids and leaves the phylogenetic position of protoceratids ambiguous.Item Open Access An Analysis of North American Taeniolabidoid Multituberculate (Mammalia, Allotheria) Dentitions Using Mammalian Dietary Proxies(2018-12-20) Robson, Selina Viktoria; Theodor, Jessica M.; Scott, Craig S.; Cote, Susanne; Syme, Douglas A.; Zelenitsky, Darla K.In this thesis, a set of dietary proxies – dental microwear analysis, cusp row ratios (CRR) (similar to shearing ratios), relief index (RFI), orientation patch count rotated (OPCR), and Dirichlet normal energy (DNE) – was used to infer diets of North American taeniolabidoid multituberculates. Based on the signals recovered by these proxies, taeniolabidoid diets did not vary consistently with body size: small-bodied and large-bodied taeniolabidoids had similar dietary signals for almost all proxies, the only difference being in microwear feature dimensions. Dental microwear signals suggest that taeniolabidoids and non-taeniolabidoid cimolodontans may have had different diets, but all other proxies have recovered equivalent signals between the two groups. Dietary classifications are inconsistent among CRR, RFI, OPCR, and DNE. This suggests that these proxies are not equally good predictors and that their generalizability to non-therian mammals may need to be re-evaluated.Item Open Access Cheek tooth morphology and ancient mitochondrial DNA of late Pleistocene horses from the western interior of North America: Implications for the taxonomy of North American Late Pleistocene Equus(PLoS ONE, 2017-08-17) Barron-Ortiz, Christina I.; Rodrigues, Antonia T.; Theodor, Jessica M.; Kooyman, Brian P.; Yang, Dongya Y.; Speller, Camilla F.Horses were a dominant component of North American Pleistocene land mammal communities and their remains are well represented in the fossil record. Despite the abundant material available for study, there is still considerable disagreement over the number of species of Equus that inhabited the different regions of the continent and on their taxonomic nomenclature. In this study, we investigated cheek tooth morphology and ancient mtDNA of late Pleistocene Equus specimens from the Western Interior of North America, with the objective of clarifying the species that lived in this region prior to the end-Pleistocene extinction. Based on the morphological and molecular data analyzed, a caballine (Equus ferus) and a non-caballine (E. conversidens) species were identified from different localities across most of the Western Interior. A second non-caballine species (E. cedralensis) was recognized from southern localities based exclusively on the morphological analyses of the cheek teeth. Notably the separation into caballine and non-caballine species was observed in the Bayesian phylogenetic analysis of ancient mtDNA as well as in the geometric morphometric analyses of the upper and lower premolars. Teeth morphologically identified as E. conversidens that yielded ancient mtDNA fall within the New World stilt-legged clade recognized in previous studies and this is the name we apply to this group. Geographic variation in morphology in the caballine species is indicated by statistically different occlusal enamel patterns in the specimens from Bluefish Caves, Yukon Territory, relative to the specimens from the other geographic regions. Whether this represents ecomorphological variation and/or a certain degree of geographic and genetic isolation of these Arctic populations requires further study.Item Open Access Chemical ecology and genetics of rough-skinned newts, Taricha granulosa(2020-05-15) Glass, Haley Cathleen; Vamosi, Steven M.; Theodor, Jessica M.; De Koning, A. P. Jason; Melin, Amanda D.Interactions between predator and prey have played a crucial role in adaptive evolutionary processes; however, phenotypic and genetic variation may also be driven by many other spatially variable biotic and abiotic factors. Rough-skinned newts, Taricha granulosa, possess a neurotoxin known as tetrodotoxin (TTX), which acts as an antipredator defense and was originally presumed to be a result of reciprocal coevolutionary interactions with resistant garter snakes across a geographic mosaic. In this thesis, I investigate several aspects of the chemical ecology and genetics of rough-skinned newts and consider how these factors play out on Vancouver Island, an interesting study region due to its isolation from mainland populations and recent non-native species introductions. By characterizing toxicity both within and among 23 populations of newts on Vancouver Island, I found significant variation in TTX and evidence for a previously unidentified hotspot, indicating selection pressures besides reciprocal coevolution may contribute to the observed patterns. Next, I present the first investigation into molecular mechanisms of tetrodotoxin expression in newts using an RNA-sequencing approach. By creating a de novo transcriptome assembly and annotation, I was able to identify novel differentially expressed genes putatively related to endogenous sources of TTX. Amphibians are also facing worldwide population declines due to factors such as negative impacts by non-native species, and Vancouver Island has experienced a recent introduction of signal crayfish and American bullfrogs. I reviewed the potential impacts of these species on rough-skinned newts and found a negative correlation between their presence and newt relative abundance, but no effect on body condition or toxicity. Using the aforementioned transcriptome assembly, I identified thousands of single nucleotide polymorphisms in 32 newts from BC and Oregon and characterized the population genetic structure at two spatial scales. Vancouver Island newts were found to belong to a cluster genetically distinct from Oregon with lower heterozygosity while displaying a lack of population structure across the island. Collectively, these results improve our understanding of the spatial variation and genetics of chemical defense in rough-skinned newts while integrating these findings with conservation implications for Vancouver Island populations.Item Open Access Diet reconstructions for end-Pleistocene Mammut americanum and Mammuthus based on comparative analysis of mesowear, microwear, and dental calculus in modern Loxodonta africana(Elsevier, 2020-01) Cammidge, Tasha S.; Kooyman, Brian; Theodor, Jessica M.We analyse mesowear, microwear, and dental calculus for end-Pleistocene Mammut and Mammuthus from North America, and modern Loxodonta africana to reconstruct diet. These three methods allow both short- and long-term diets to be distinguished. As microwear analysis shows a negative correlation between the numbers of pits and scratches counted, the proportions of pits/(pits + scratches) were used for analyses rather than gross counts. The three types of analyses confirm that modern Loxodonta africana are grazers or mixed-feeders. Microwear analysis demonstrates that end-Pleistocene Mammut were primarily browsers but may have changed their diets opportunistically or seasonally to graze. Mesowear analysis of end-Pleistocene Mammuthus indicates a grazing diet, but microwear analysis indicates a mixed-feeding diet. Dental calculus analysis demonstrates that all three species were mixed-feeding to varying degrees. Results show that extinct proboscidean diet was more complex than previously thought, and may contradict previous work suggesting that Mammut were browsers and Mammuthus were grazers. Using mesowear and microwear, we found no significant differences in pre- and post-glacial diet for fossil proboscideans. However, using dental calculus, we found that for pre-glacial specimens there was a larger proportion of tiny (i.e. less than 8 μm wide) grass starch granules, whereas for post-glacial specimens there is a larger proportion of large (i.e. greater than 20 μm wide) grass starch granules with lamellae, suggesting with a shift in Mammut and Mammuthus diet during the end-Pleistocene. Specimens commonly had different dietary signals depending on the method utilized, suggesting that a multi-faceted approach is required to fully elucidate proboscidean diet.Item Open Access An Earliest Carboniferous Actinopterygian Fauna from the Horton Bluff Formation of Nova Scotia(2020-01) Wilson, Conrad Daniel Mackenzie; Anderson, Jason S.; Theodor, Jessica M.; Cote, Susanne; Jamniczky, Heather A.; Anderson, Jason S.This thesis examines four earliest Carboniferous (Tournaisian) actinopterygian specimens from the Horton Bluff Formation of Nova Scotia. I used traditional and μCT descriptive techniques in order to better understand actinopterygian evolution and the transition between Devonian and Carboniferous vertebrate faunas. NSM 017.GF.017.001 was investigated using microscopy and latex peel techniques and represents the oldest occurrence of a deep-bodied actinopterygian. NSM 017.GF.017.007 and NSM 017.GF.017.004 were investigated using microscopy and μCT. Neither specimen can be assigned to genus or species, however, each can be compared to a broader group. NSM 017.GF.017.007 is most similar to Devonian taxa, whereas NSM 017.GF.017.004 is most similar to actinopterygians deeply nested in a broad post-Devonian radiation. NSM 017.GF.017.005 was examined using μCT and was incorporated into a phylogenetic analysis. In this specimen, the plesiomorphic anatomy of the dermal shoulder girdle, pectoral fin, and opercular-gular series are contrasted with the derived anatomy of the hyoid arch. In the phylogenetic analysis, it is recovered as a late-diverging member of a grade of otherwise Devonian actinopterygians. The presence of NSM 017.GF.017.001 and NSM 017.GF.017.004 suggests that derived actinopterygians faunas were established by the Tournaisian; whereas the presence of NSM 017.GF.017.007 and NSM 017.GF.017.005 suggests that Hangenberg extinction survivorship was inclusive of early-diverging actinopterygians. NSM 017.GF.017.001 and NSM 017.GF.017.005 also evince actinopterygian body plan exploration, perhaps related to resource acquisition, in the Tournaisian and revise previous models of post-Hangenberg actinopterygian differentiation. More broadly, the disparity of this fauna weakens interpretations of a homogeneous earliest Tournaisian caused by mass extinction and suggest that faunal turnover was more gradual than expected, at least in Actinopterygii.Item Open Access Ecology and Genetics of Phenotypic Integration and the Role for Adaptation in Threespine Stickleback(2019-07-09) Barry, Tegan Nicole; Rogers, Sean M.; Jamniczky, Heather A.; Theodor, Jessica M.; Vamosi, Steven M.Determining the underlying causes for the links between form, function, and the environment, and how these correlations relate to adaptation to novel environments represent integral problems in evolutionary biology. While investigations have been conducted on adaptive divergence involving single, isolated traits, adaptation is multifaceted, requiring the examination of complex, multidimensional phenotypes. In this thesis, I evaluated the hypothesis that phenotypic covariation and phenotypic integration are linked to genetic covariation and facilitate adaptation to novel environments. Phenotypic variation and covariation, along with genetic differentiation between multiple wild stickleback subpopulations and laboratory reared groups were described using three dimensional geometric morphometric data from stickleback skeletal structures as well as genomic information from high density Single Nucleotide Polymorphisms (SNPs; sensu Pool-Seq). I evaluated whether divergence in putatively adaptive traits was higher than expected under expectations for neutral evolution via PST-FST comparisons of phenotypic covariation and contrasted patterns of genetic and phenotypic variation. I determined the genetic basis of phenotypic integration using a controlled common garden experiment and investigated the genetic architecture of integrated skeletal structures through Quantitative Trait Locus (QTL) analysis carried out on linkage maps that I generated from SNPs characterized by double restriction digest reduced representation sequencing (ddRAD-Seq). Finally, I evaluated whether this genetic architecture was being maintained by selection in wild populations by testing the hypothesis that molecular divergence was higher than expected at genetic regions associated with phenotypic traits. I found the amount of phenotypic variation and strength of integration varies across the stickleback skeleton as well as among marine populations and that directional selection is acting on phenotypic integration in all observed populations. I determined that phenotypic integration across the skeleton is controlled by genetic factors, though there is a strong effect of environment on trophic traits. Finally, I characterized 33 significant QTL linked to integrated skeletal traits, finding 2702 SNP outliers within the identified QTL under selection between marine and freshwater environments. Collectively, my thesis highlights integration as an essential component of adaptive divergence and as one of the potential driving forces for the rapid adaptation of populations to novel environments.Item Open Access Ecology of Adaptive Peak Shifts in Alaskan Threespine Stickleback (Gasterosteus aculeatus)(2015-12-04) Vanderzwan, Stevi Lee; Rogers, Sean M.; Vamosi, Steven M.; Jamniczky, Heather A.; Theodor, Jessica M.Divergent natural selection is a major cause of phenotypic differentiation among populations exploiting different environments, but information on the ecological factors contributing to peak shift is largely missing from natural populations. Threespine stickleback (Gasterosteus aculeatus) is an emerging vertebrate model for studying phenotype-environment associations, as ancestral marine populations have adapted independently to postglacial freshwater environments. I characterized antipredator, foraging, and body shape phenotypes of 800+ fish from 16 ecologically diverse sites on the Alaska Peninsula. Gill rakers, antipredator traits, and body shape significantly associated with lake ecology, whereas foraging traits and body shape were influenced by geography. Stickleback from lakes ecologically similar to the ancestral state were more phenotypically similar to marine-influenced populations than fish from ecologically divergent habitats (i.e., small lakes). My study elucidates mechanisms associated with adaptive evolution and is one of relatively few that links ecological features of the adaptive landscape with phenotypic evolution in multiple populations.Item Open Access Enamel hypoplasia and dental wear of North American late Pleistocene horses and bison: An assessment of nutritionally based extinction models(Cambridge, 2019-06-03) Jass, Christopher I.; Austen, Jennifer; Theodor, Jessica M.; Barrón-Ortiz, Christina I.; Barrón-Corvera, RaúlApproximately 50,000–11,000 years ago many species around the world became extinct or were extirpated at a continental scale. The causes of the late Pleistocene extinctions have been extensively debated and continue to be poorly understood. Several extinction models have been proposed, including two nutritionally based extinction models: the coevolutionary disequilibrium and mosaic-nutrient models. These models draw upon the individualistic response of plant species to climate change to present a plausible scenario in which nutritional stress is considered one of the primary causes for the late Pleistocene extinctions. In this study, we tested predictions of the coevolutionary disequilibrium and mosaic- nutrient extinction models through the study of dental wear and enamel hypoplasia of Equus and Bison from various North American localities. The analysis of the dental wear (microwear and mesowear) of the samples yielded results that are consistent with predictions established for the coevolutionary disequilibrium model, but not for the mosaic-nutrient model. These ungulate species show statistically different dental wear patterns (suggesting dietary resource partitioning) during preglacial and full-glacial time intervals, but not during the postglacial in accordance with predictions of the coevolutionary disequilibrium model. In addition to changes in diet, these ungulates, specifically the equid species, show increased levels of enamel hypoplasia during the postglacial, indicating higher levels of systemic stress, a result that is consistent with the models tested and with other climate-based extinction models. The extent to which the increase in systemic stress was detrimental to equid populations remains to be further investigated, but suggests that environmental changes during the late Pleistocene significantly impacted North American equids.Item Open Access Juvenile specimens of Prosaurolophus maximus (Hadrosauridae, Saurolophinae) from the marine Bearpaw Formation (upper Campanian, Upper Cretaceous) of southern Alberta, Canada reveal ontogenetic change in crest morphology(2019-01-25) Drysdale, Eamon Thomas; Zelenitsky, Darla K.; Therrien, François; Theodor, Jessica M.; Dutchak, AlexanderThree juvenile specimens of Prosaurolophus maximus, represented by both articulated and disarticulated skeletal material, are the smallest known individuals for the taxon. Their cranial anatomy indicates that the diagnostic characters of P. maximus are ontogenetically variable. In the smallest specimen, the crest and deeply-excavated fossa at the caudal margin of the circumnarial depression are poorly-developed or absent. In the larger specimens, the crest approaches the morphology observed in subadult and adult specimens but lacks the robusticity and deep excavation of the circumnarial depression typical of P. maximus. In contrast, the shape of the caudal end of the circumnarial depression is ontogenetically consistent, potentially making it a reliable character for taxonomic identification. Histological sections from the three juvenile specimens and one large individual indicate that the minimum biological age of the known specimens of P. maximus ranges from two to five years. Given that the large P. maximus individual has yet to reach skeletal maturity, the species may reach a maximum body size larger than represented by currently known specimens, perhaps with a skull length approaching the size of Saurolophus angustirostris. The lack of positive allometric growth associated with the P. maximus crest, which undergoes isometric growth from age three onward, differs from that observed in lambeosaurine hadrosaurs suggesting that the crest may not have been the result of sexual selection. However, positive allometric growth of the circumnarial region and the rugosity of the bony crest suggests that soft tissue structures associated with the narial-crest region, rather than the bony crest itself, may have been selected for sexual display in P. maximus. The juvenile specimens were recovered from sediments of the Bearpaw Formation deposited during the Baculites compressus ammonite zone and magnetochrons 33n.3n to 33n.2n. They are stratigraphically younger than P. maximus specimens from the Dinosaur Park Formation, and contemporaneous to 100,000 years younger than specimens from the Two Medicine Formation, extending the taxon’s temporal range. The occurrence of P. maximus in the marine deposits of the Bearpaw Formation and well-drained upland terrestrial deposits of both the Dinosaur Park and Two Medicine formations suggests that this taxon inhabited various palaeoenvironments.Item Open Access Models of Energetically Optimal Locomotion in Cursorial Mammals(2020-02-14) Polet, Delyle Thomas; Theodor, Jessica M.; Bertram, John Edward Arthur; Pieper, Jeffery Kurt; Syme, Douglas A.; Kuo, Arthur D.; Carrier, David R.It is widely held that cursorial mammals use gaits that minimize the energetic cost of locomotion, but it is hard to compare alternative strategies in real organisms. In this thesis, I show how simple models can inform and predict the gaits used by cursorial mammals from an energetics perspective. A simple work optimization model predicts how human subjects reduce their takeoff velocity and "bounciness" while running in reduced gravity. This work-based perspective is extended to quadrupeds using trajectory optimization, where it is shown that an additional term– the so-called force-rate penalty– is necessary to explain some features of canid locomotion. The shape of ground reaction forces, leg sequence at slow to moderate speeds, changes in duty factor at moderate to fast speeds, and the walk-trot transition are all predicted by this planar model. Next I use this model to show how changing pitch moment of inertia affects energy-optimal gait choice, matching gait preferences between dogs, horses, giraffes and elephants. Finally, I compare various modelling approaches used for four-legged mammals, and show how center-of-mass considerations alone do not explain the typical, four-beat walking gait used by most cursorial quadrupeds– despite the success of the center-of-mass approach in humans, as demonstrated in this very thesis. These results show that energetic optimization can be remarkably predictive of gait choice in mammalian cursors, even with a small number of modelling components. Where the predictions are deficient, they point to missing levels of complexity that could be added in future models.Item Open Access A multimethod analysis to assess locomotor capabilities in stem tetrapods from Blue Beach (Tournaisian; Early Carboniferous), Nova Scotia(2020-01) Lennie, Kendra Ilana; Anderson, Jason S.; Theodor, Jessica M.; Jamniczky, Heather A.; Manske, Sarah LynnIn vertebrate evolution the fin-to-limb transition was an important precursor to the diversification and radiation of terrestrial animals into novel environments. This transition began in the Devonian and continued through the Carboniferous and involved physiological and biomechanical changes. I used a multi-method approach to assess external and internal limb bone features to evaluate Early Carboniferous (Tournaisian) limb bones from Blue Beach and associated them with aquatic to terrestrial lifestyles. Tournaisian tetrapod material was collected at Blue Beach located near Hantsport, Nova Scotia, but much of it has not been formally described because the disarticulated and isolated tetrapod elements made identification to the species level difficult. In this thesis I described new morphotypes attributable to the family level which are used in the following chapters. Once the external morphology of the Blue Beach bones was described I compared them with the femora of extant aquatic, amphibious, and terrestrial tetrapods to evaluate which locomotor behaviour the fossil femora most resembled. I additionally examined cross-sectional bone profiles of Blue Beach tetrapod femora to infer lifestyle. Midshaft analyses relied on a single two-dimensional image to represent a dynamically structured bone so I also used a novel method for assessing three-dimensional trabecular data to qualitatively and quantitatively infer lifestyle from the Blue Beach femora. From the various analyses of internal and external bone morphology it was clear that external bone features of modern and early fossil tetrapod femora are dissimilar, which lead to difficulties in drawing conclusions based off external qualitative data. Internal data, from two-dimensional midshaft and three-dimensional trabecular structures, produced quantitative results that lead to the same conclusion, that the Blue Beach femora are consistent with those of aquatic animals. This implies that the initial diversification of the tetrapod body plans present in the Early Carboniferous was not the result of terrestrialization but appears to have preceded it.Item Embargo Osteology and Histology of Plesiosaurs (Reptilia: Sauropterygia) from Non-marine (Fluvial to Estuarine) and Marine Depositional Environments(2019-12-19) Campbell, James Alexander; Anderson, Jason S.; Theodor, Jessica M.; Henderson, Donald M.; Caldwell, Michael W.; O'Keefe, Frank Robin; Dutchak, Alex R.Plesiosaurs are a highly diverse group of secondarily-aquatic reptiles that lived from Late Triassic to Late Cretaceous time. Plesiosaurs are known primarily from marine deposits, but also occur sparingly in non-marine units. Here, I describe the osteology and histology of plesiosaurs from both non-marine (Dinosaur Park Formation, DPF) and marine (Bearpaw and Pierre Shale Formations; BF, PSF), Upper Cretaceous-aged deposits of western Canada. These sediments were deposited in the Western Interior Basin, which was inundated by a large marine corridor known as the Western Interior Seaway. Non-marine (fluvial to estuarine) sediments of the DPF have yielded a stratigraphically extensive collection of elasmosaurid plesiosaur specimens. These specimens are notable as they belong to individuals that are small-bodied relative to some elasmosaurid specimens from marine units. In this study, I test whether the small-bodiedness of DPF specimens is due to the presence of immature individuals or a small-bodied taxon. Analyses of select DPF elasmosaurid specimens indicate the presence of a small-bodied taxon. Furthermore, a well-preserved partial skeleton from this unit is recognized as the holotype of a new genus and species. The holotype and referred specimens span both estuarine and fluvial sediments and may indicate an example of niche-partitioning within the predominantly marine Plesiosauria. The small body size is also consistent with those of plesiosaurs from other non-marine units. I also describe select elasmosaurid and polycotylid specimens from the BF and PSF, respectively. One elasmosaurid belongs to a large-bodied taxon which may be closely-related to, or possibly conspecific with, the DPF taxon. Another elasmosaurid belongs to a small-bodied, likely new, taxon. The two polycotylids were originally considered to be a juvenile and adult of Dolichorhynchops bonneri, based on their similar morphologies and large discrepancy in size. However, both specimens are osteologically mature, possibly reflecting interspecific differences; alternatively, these body size differences may be due to sexual dimorphism. Finally, this dissertation constitutes one of the first histological studies on plesiosaurs from non-marine units and Canada. This study also contributes to our limited understanding of plesiosaur ontogeny.Item Open Access Paleoenvironmental Reconstruction of Kalodirr and Moruorot, Kenya using Stable Carbon Isotopes(2019-01-24) Butts, Catherine Frances Rita; Cote, Susanne; Theodor, Jessica M.; Katzenberg, Mary AnneEarly Miocene environments in East Africa are proposed to have consisted of entirely dense forest systems composed strictly of C3 vegetation, which has affected our understanding of Miocene ape habitats. However, new environmental data from the early Miocene sites of Moroto (21 Ma), Napak (20 Ma), Tinderet (20 Ma), Rusinga Island (20-18 Ma), and Bukwa (19 Ma) indicate a more open environment consisting of open canopied forests, woodlands and wooded grasslands with evidence of some C4 vegetation. This study builds on this new data by analyzing stable carbon isotopes in mammalian tooth enamel collected from Kalodirr and Moruorot, Kenya (17.5-16.8 Ma). These δ13Cenamel signatures suggest a mosaic of C3 vegetation too enriched to indicate a closed canopy forest. Rather, they are more similar to values found in woodlands, with some indications of C4 vegetation. This supports the hypothesis that the forest canopies of East Africa were opening before the middle Miocene, demonstrating that the environmental history of East Africa was more dynamic than previously described.Item Open Access Phenological responses to climate in the Alberta native flora: Herbarium specimens reveal differential responsiveness between species in mesic and xeric habitats(2019-03-01) Porto, Cassiano; Vamosi, Jana C.; Goldblum, David; Theodor, Jessica M.; Yeaman, Sam; Quinney, Annie E.The field of phenology focuses on investigating the timing of biological events and phases of life cycles. In the face of projected and ongoing climate change, there is a growing interest in detecting the effects of climate change on plant phenology. This research focuses on using herbarium specimens to examine whether 14 native plant species in Alberta have adjusted to changes in temperature and precipitation over the past century. I hypothesize that the soil moisture to which plants are exposed might affect their phenological responses and investigate: if herbaria collections contain evidence of phenological responses to climate in species of the Alberta flora, and if the responses are dependent on the typical moisture regime of their habitat. Plants from mesic and xeric habitats are compared in terms of phenological responses to air temperature and precipitation. The taxonomic relationships between the species were taken into account, by selecting a total of 14 species representing seven different angiosperm orders (one pair of species for each order). For each selected species, the preserved specimens available at three major Albertan herbaria collections were included in the study, if showing more than 50% of flower buds in anthesis (defined as peak flowering). The peak flowering date of each specimen, combined with the average temperature (or total precipitation) of the species’ mean flowering month and the three months prior, allowed the use of a regression model for the estimation of a species’ phenological responsiveness. The linear multiple regression analysis has revealed a significant responsiveness to temperature for six species from xeric habitats and one species from mesic habitats. My results suggest that species from xeric habitats have an average phenological responsiveness to temperature significantly more pronounced than species from mesic habitats. This tendency might be explained by the thermal properties of mesic habitats. The results indicate that for some species there is a set of environmental cues, as opposed to only one parameter, that governs flowering timing. The elucidation of the ecological implications involving plants phenological responses is key for the development of effective ecosystem conservation programs in the context of global climate change.Item Open Access The molecular systematics of the Agabinae Thomson, 1867 (Coleoptera, Dytiscidae)(2016) Venables, Chandra; Vamosi, Steven M.; Theodor, Jessica M.; Rogers, SeanEarly 19th century classifications of the predaceous diving beetle subfamily Agabinae have been continuously reworked by subsequent systematists, but remain in flux at all taxonomic levels. Morphological characters have not produced sufficient evidence for a robust phylogeny, as there are few informative characters on which to base the taxonomy below the level of subfamily. It has been 12 years since the only comprehensive analysis of the molecular systematics and biogeography of the subfamily was published by Ribera et al. (2004). In the current project I update the molecular systematics of the Agabinae, addressing problems of biogeography, diversification rate, and taxonomy, at the subfamily, genus, and species levels. I apply dense taxon sampling, including data from the previously underrepresented Neotropical, Northern Nearctic, Eastern Palearctic, and Afrotropical regions, to a dataset of 10 gene sequences; (five mitochondrial, five nuclear). Using Bayesian and likelihood approaches, as well as fossil data, I infer time-calibrated phylogenies for the subfamily and for the genus Agabus. My results indicate the Agabinae originated during the early Paleogene in the Northern Hemisphere, with expansions to Australasia and South America likely via long distance dispersal. The tribes Agabini and Platynectini were consistently recovered as monophyletic, as was Hydrotrupini; however, results suggest that Hydrotrupes should be elevated to subfamily Hydrotrupinae. Relationships within and between genera were consistently recovered with strong Bayesian support with the exceptions of the relationship between Platambus and Agabus, species groups of Ilybius and Agabus, and for the subgenera of Agabus. In addition to polyphyletic Platambus occurring in Agabus, 44% of the current Agabus species groups (not monotypic) were not recovered as monophyletic. Collections in Northern Canada and Alaska yielded new locality data for 9 species, and identified possible refugial populations of Agabus arcticus (Paykull, 1798) in the Peel watershed (Yukon Territory). Further study of A. arcticus in the Nearctic will likely support the recognition of unique Nearctic subspecies. Molecular phylogenetic results provide new insights into Agabinae systematics, and also find support for many taxonomic hypotheses developed by the pre-cladistic workers in the group, underscoring the importance of integrative taxonomy combining molecular (this project) and morphological data (past workers).Item Open Access Using the Price Equation to Quantify Species Selection and Other Macroevolutionary Forces in Cretaceous Molluscs(2019-08-12) Jordan, Katherine J.; Fox, Jeremy W.; Theodor, Jessica M.; Summers, MindiSpecies selection and other macroevolutionary forces are challenging processes to study and quantify when using fossil data. Here, I used the Price equation to analyze changes in geographic range sizes prior to and during a mass extinction event to estimate the relative contribution of three macroevolutionary processes (species selection, anagenesis, and immigration). I also tested the hypothesis that larger geographic range size increases a group’s survivability during mass extinctions. I applied a similar method to Rankin et al. (2015) to study marine gastropods and bivalves of the Gulf and Atlantic Coastal Plain (originally studied by Jablonski (1987)) over the last 16 million years of the Cretaceous Period. I found three major changes in mean geographic range size shared by both gastropods and bivalves during the end-Cretaceous: an increase in mean range size during the late Campanian, a decrease in the mid-Maastrichtian, and an increase near the end of the Cretaceous Period (late Maastrichtian). The Price Equation indicates that the late Campanian increase in geographic range size was attributable primarily to immigration, the mid-Maastrichtian decrease was due to different combinations of the three processes (species selection, anagenetic change, and immigration) in gastropods and bivalves, and the late Maastrichtian increase was attributable to species selection. These changes in geographic range size coincide with a marine transgression event, a period of global climate change, and a marine regression event, respectively. A statistically significant correlation between larger geographic range size and increased survivability was found for one time increment (approximately four million years before the KPg boundary). This study shows that the relative contribution of interacting macroevolutionary processes fluctuated over the end-Cretaceous extinction event and suggests that large geographic range size can increase survivability under certain conditions leading up to a mass extinction.