Theses (Biology)

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Theses from the Dept. of Biology.

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Impacts of heatwaves and hypoxia on gene expression in the pacific oyster and the development of monitoring and mitigation tools for summer mortality
(2025) Bickell, Andrew; Pearce, Christopher Michael; Bates, Amanda
Marine heatwaves and coastal hypoxic events are increasing in frequency and intensity under anthropogenic climate change, resulting in widespread mass mortalities of the Pacific oyster (Crassostrea gigas). Those mortality events threaten the economic stability of global aquaculture, yet strategies to monitor oyster health and mitigate losses during periods of environmental stress are largely limited. Changes in gene expression of C. gigas in response to laboratory-simulated heatwaves and hypoxic events were assessed to identify candidate monitoring genes and explore artificial aeration as a potential mortality mitigation strategy. Two laboratory experiments were performed, exposing farmed C. gigas to simulated 10-day heatwave and hypoxic conditions similar to a 2021 marine heatwave that triggered farmed oyster mortality in Baynes Sound, British Columbia, Canada. Gill tissues were periodically sampled during the experiments and total RNA was extracted to explore patterns of gene expression via RNAseq and qPCR. Five candidate genes were consistently differentially expressed in both experiments— death-associated inhibitor of apoptosis 2 (A2I), high mobility group protein DSP1 (DSP1), high mobility group box 1 (HMGB1), heat shock protein 90 (HSP90), and peptidyl-prolyl cis-trans isomerase (PPCTI)—demonstrating potential for monitoring summer mortality. No significant differences in expression of the general stress marker genes heat shock protein 70 (HSP70) and heat shock protein 20 (HSP20) were detected, suggesting that genes related to immune function and regulation of transcription may be more appropriate for monitoring summer mortality. In addition, the presence of artificial aeration resulted in significantly lower HSP90 relative expression, suggesting some potential utility in stress mitigation during heatwaves. The present work provides insights into the role of heatwaves and hypoxia in Pacific oyster summer mortality and will inform effective monitoring and mitigation practices to support the adaptation of shellfish aquaculture to the growing impacts of climate change.
Monitoring deep-sea MPAs: Functional and trait-based approaches for adaptive management in changing oceans
(2025) Davies, Megan A.; Bates, Amanda; Du Preez, Cherisse
Changing ocean conditions are disrupting marine ecosystems, posing significant challenges for monitoring and managing biodiversity in remote, offshore marine protected areas (MPAs). Effective conservation depends on biological assessment tools that can overcome the logistical constraints of deep-sea monitoring while detecting long-term ecological changes. This thesis evaluates two possible approaches for assessing and monitoring species in offshore MPAs. First, I assess the feasibility of a functional-group monitoring approach, using cold-water corals and sponges (CWCS) in the Northeast Pacific as a case study. I analyze inter- and intra-seamount variability in depth-occupancy patterns using data extracted from remotely operated vehicle (ROV) transects performed by Fisheries and Oceans Canada (Chapter 2). Additionally, I identify potential indicator species that could be used to streamline long-term monitoring efforts. Second, I develop a species-level vulnerability framework using functional traits, with molluscs in the Azores Marine Park as a case study. I conduct a comprehensive literature review to determine which traits are most relevant for assessing vulnerability to climate change. Using species trait data from the FUN Azores Trait Database, I integrate oceanographic models to quantify species-specific exposure, sensitivity, and adaptive capacity to ocean acidification and warming (Chapter 3). My findings show that while functional groups capture broad CWCS distribution patterns, species-level assessments remain necessary for detecting ecological changes and refining monitoring strategies in the NE Pacific. In the Azores, I find that bivalves in northern MPAs are particularly vulnerable due to their high sensitivity and low adaptive capacity, while cephalopods exhibit greater resilience to climate change. Together, these studies highlight the strengths and limitations of biological assessment tools for long-term deep-sea MPA monitoring, offering insights into their role in adaptive conservation strategies. By integrating functional-group and trait-based approaches, this thesis contributes to a more adaptive and effective conservation framework for managing marine species in a changing ocean.
Physiological and behavioural responses of a keystone predator, Pisaster ochraceus, to periodic aerial heat stress
(2025) Walton, Lydia; Bates, Amanda
Extreme heat events are becoming more frequent and intense, requiring a better understanding of how temperature variability influences species performance and interactions. When temperatures approach critical thermal limits, disruptions to individual behaviour and physiology, such as reduced prey consumption and suppressed metabolic activity, can have cascading effects on ecosystem functioning. These effects can be especially widespread when keystone predators are negatively impacted, as they exert a disproportionate effect on their community relative to their biomass. My thesis investigates how periodic aerial heat stress relates to mortality, feeding, metabolism, and body surface temperature in juvenile Pisaster ochraceus (ochre sea star, hereafter Pisaster), a keystone intertidal predator. Through controlled laboratory experiments, I show that exposure to extreme aerial temperatures (~30°C) increases mortality by 33% and reduces mussel consumption to half of that observed in animals experiencing typical aerial temperatures (~20°C or 25°C). Furthermore, cooler seawater (~15°C) exacerbates these adverse effects, leading to a 17% increase in mortality, and ~50% reductions in feeding and metabolic rates compared to individuals exposed to high aerial temperatures (~30°C) under warmer seawater (~20°C). To further assess the effects of temperature variability, I use infrared thermography (IRT) to examine the body surface temperatures of Pisaster (n = 738) from eight beaches during summer low tides on Vancouver Island and relate these temperatures to biological factors and environmental conditions. I found that Pisaster use several strategies to minimize thermal stress in the field. Specifically, the selection of shaded microhabitats and the use of evaporative cooling allow Pisaster to maintain body surface temperatures up to 14°C degrees cooler than the ambient air and up to 6°C cooler than ambient sea surface temperatures. Even so, some individuals were found in sun exposed microhabitats, and in those rare cases, body surface temperatures exceeded ambient air temperatures by 2°C. The integration of manipulated experiments with field monitoring reveals that increasing air-sea surface temperature disparities could reshape community dynamics through shifts in keystone predation, however, the severity of thermal stress may be reduced through behavioural and physiological buffering strategies.
Quantification of melanopsin gene expression during sablefish (Anoplopoma fimbria) development and spatial mapping of Opn4m proteins on a newly established brain atlas
(2025) Mokariasl, Niloufar; Taylor, John Stewart
In this research, I investigated opsins in sablefish (Anoplopoma fimbria). Sablefish is a fast-growing teleost species that experiences a unique developmental environment, traveling to the surface from a kilometer deep in the ocean across embryonic and larval stages. Teleost fish, in particular, have a high number of opsins due to the third genome duplication event and the retention of opsins after duplication. I uncovered 38 opsins in sablefish despite the fact that they spend most of their life in the ocean’s aphotic zone. I focused on melanopsin/Opn4, an evolutionarily conserved subfamily of non-visual opsins, with a well-established role in the maintenance of circadian rhythm in mammals. Despite this well-researched role, melanopsin shows expression in a diversity of cell and tissue types, suggesting the possibility of other functional roles. I examined these genes across four distinct life stages using qPCR and identified gene expression in whole larva at 30 days post-fertilization (dpf), in the larval brain at 82 dpf, and in the brain, eye, and heart of juveniles, as well as in the brain and heart of adults. Using fluorescent immunolabeling on sablefish optic tectum sections, I localized Opn4m proteins for the first time in the endfeet of radial glial cells and likely in neuroepithelial cells within the juvenile optic tectum. The immunolabeling data on juvenile sablefish eye also revealed the expression of these proteins in all layers of the retina, including outer nuclear layer (ONL), outer plexiform layer (OPL), inner nuclear layer (INL), and ganglion cell layer (GCL). Using qPCR, I have also quantified the expression of these genes throughout sablefish development from unfertilized eggs through all embryo stages and to the oldest larval stage. Furthermore, I examined the localization of Opn4m protein(s) in brain and eye of the four larval stages (18, 29, 36, and 47 dpf) to identify the cells that express these proteins. In this study, we report changes in expression of five melanopsin genes over embryonic and larval development, from unfertilized egg to 47 dpf. Using fluorescent immunolabeling and immunogold labeling, we also report for the first time, the expression of Opn4m proteins in proliferative neural cells, radial glial cells, and potentially astroglia in the brain over larval development. Unsurprisingly, we also found these proteins expressed in amacrine, bipolar, horizontal, and photoreceptor cells in the retina of 47 dpf sablefish, a similar pattern of expression to that observed in zebrafish larvae, sablefish juveniles and adult zebrafish. While melanopsin is best known for expression in intrinsically photosensitive retinal ganglion cells (ipRGCs) and for its role in circadian rhythm entrainment, an often-neglected observation is that when first described, melanopsin was detected in X. laevis retinal photoreceptors. It has since been found in photoreceptors of reptiles and ray-finned fish. In zebrafish (Danio rerio) an immunoprobe that binds to three of the five Opn4 paralogs showed a ring-like pattern of expression in cone cell inner-segments (Davies et al., 2011). No explanation for this was offered. I revisited this unusual pattern of expression using transmission electron microscopy and we looked for evidence of melanopsin expression in photoreceptors of a distant relative, the sablefish (Anoplopoma fimbria). Immunogold labeling was observed in outer segments and in ellipsoid megamitochondria of cone cells in both species Additionally I created the brain atlas for early sablefish brain development to guide my immunolabeling findings in larval stages. Using hemotaxylin and eosin staining (H&E) and ultramicrotomy, I have provided a developmental series of sablefish eye and brain sections, and created the partial brain atlas. The eye and brain atlas reported here includes three- and four-micron sections (942 in total) from 18, 29, 36, and 47 days dpf sablefish. Sections start at the olfactory bulb and run to the posterior medulla. Brain atlases with similar resolution are available for only a few other fishes, including zebrafish (Danio rerio) and medaka (Oryzias latipes). This resource is developed to provide a histological perspective on opsin gene expression data, but also makes an important contribution to the understanding of neurodevelopment in ray-finned fish. Sablefish take 47 days to reach the same stage of eye and brain development as 5 dpf zebrafish. Apart from this difference in rate, development is similar to both zebrafish and medaka, despite large differences in life history, morphology and behavior.
Using iron deficiency stress in plants as a tool for discovery of novel iron chelators for human use
(2024) Lane, Sarah; Ehlting, Jürgen; Walter, Patrick B
Iron is an essential micronutrient for life, but has harmful effects when dysregulated, especially when this leads to its accumulation in the body. Iron overload in humans contributes to the pathology of diseases like thalassemia, cancer and Parkinson’s Disease (PD). Treatments for iron overload can include chelation therapy to bind iron and remove it from tissues, but options authorized for clinical use are limited and can cause severe side effects. Plants are a good source of specialized, bioactive metabolites, and may be an untapped resource for novel iron chelators, as they produce these in roots to acquire environmental iron. This research uses a directed screening approach to find new chelators, taking advantage of plant biology by reducing iron in the plant growth environment to stimulate the production of iron-related metabolites, then testing them in a cell culture model of systemic iron overload. Of three species explored in this research, Populus trichocarpa x P. deltoides (poplar) was shown to be the most promising candidate for iron chelator production. It had a widespread response to iron reduction, including increased production of sideretin, a known iron chelator, and trichocarpin, a salicinoid not previously associated with iron deficiencies. In phytochemical screening, it was mainly non-toxic and had dose-dependent antioxidant activity in unstressed THP-1 monocytic cells. When used in a model of systemic iron overload, it did not significantly decrease intracellular iron in these cells, but biological variation in source plants had a considerable effect on bioactivity. When a component of poplar root extract, chlorogenic acid, was used instead, it exerted a significant dose-dependent reduction of intracellular iron content. Modeling brain iron overload and chelation therapy in vitro is more challenging, and the final component of this research was to explore induced pluripotent stem cells as dopaminergic neurons in monolayer and 3D cell constructs for future modelling of chelation therapy. Patient-derived iPSC were successfully established in 3D culture as a stepping stone to investigating the use of iron chelators in 3D printed tissues. This work contributes to our understanding of iron acquisition strategies in plants, and presents novel ways to discover new therapeutic agents through plant-biology directed screening and innovative technology.
Nutrient physiology of siliceous phytoplankton under warming and acidification in Arctic and subtropical oceans
(2024) Wyatt, Shea; Varela, Diana Esther
Steadily rising atmospheric CO2 concentrations have the potential to impact marine ecosystems by increasing the temperature and acidity of the world’s oceans. In the sunlit upper ocean, phytoplankton affect elemental cycling and contribute to nutrient export to deeper waters by incorporating nutrients into biomass and supporting higher tropic levels. One unique group of phytoplankton, diatoms, are characterized by their typically larger size and heavy silica frustules, and they make considerable contributions to global primary productivity. Diatoms are expected to be impacted by oceanic change in various ways, but the degree of this effect is still uncertain. The overall objective of this thesis is to improve our understanding of how marine diatom physiology, specifically the utilization of silicon (Si), and the contribution by diatoms to the cycles of carbon (C) and nitrogen (N), are affected by climate-induced increases in temperature and acidification. I investigated the impact of mesoscale physical processes on diatom contributions to utilization rates of C (ρC) and nitrate (ρNO3) in the Sargasso Sea in the North Atlantic subtropical gyre, an ecosystem impacted by increased stratification due to ocean warming. Diatoms played a minor role in nutrient utilization and biomass during the lowest-productivity time of year, but they dominated nutrient utilization rates in the deeper euphotic zone of the Sargasso Sea when nutrient concentrations were enhanced by eddy-driven upwelling. In the contrasting environment of the Bering and Chukchi Seas, I investigated the effects of a warming ocean on diatom physiology and elemental composition as part of an on-going oceanographic time-series in the Pacific Arctic Region (PAR). I found significant trends in ocean temperature and sea ice breakup dates for different regions of the PAR, and evidence for declining diatom biomass in one area of the northern Bering Sea. Anomalously low particulate C:N values were observed across the PAR during the 2019 MHW, but otherwise the response of diatom assemblages in the PAR to a sustained warming period and marine heatwave (MHW) in 2019 varied substantially. Estimates of diatom contributions to ρC and ρNO3 in the PAR were improved compared to previous studies, demonstrating that diatoms were responsible for most of the nutrient utilization in all regions. Ocean acidification experiments were conducted with a model diatom species and two natural phytoplankton assemblages to assess the effects of decreased pH on nutrient physiology. Overall, diatom Si utilization and silicification in laboratory and field culture experiments were unaffected by pH. I found that the cell size of a model species of diatom, Thalassiosira rotula, decreased under OA, while in subtropical and Arctic phytoplankton assemblages, OA had no conclusive meaningful impacts on other measures of physiology, or assemblage composition. This dissertation provides valuable insights into how siliceous phytoplankton, particularly diatoms, interact with marine cycles of Si, C, and N across cold and warm marine ecosystems. It also deepens our understanding of how these dynamic systems may respond to oceanic change, and sets the stage for future research on the evolving impacts of climate-driven physical processes.
AMPA and NMDA receptor localization and recruitment in a central circuit of the mammalian retina
(2024) Chundekkad, Pavitra; Awatramani, Gautam
Retinal direction-selective ganglion cells (DSGC) have the ability to encode direction of moving objects over a wide range of contrasts. In part, the DSGC response is shaped by graded excitatory information mediated by glutamatergic bipolar cells, via specialized ribbon synapses. Glutamate signals to DSGCs are known to be mediated via two types of receptors: AMPA and NMDA receptors (AMPARs & NMDARs, respectively). The main aim of my thesis was to investigate how AMPARs and NMDARs are distributed at the sub-cellular and synaptic levels, in an effort to understand how DSGCs encode responses over a range of conditions. My research employed patch-clamp electrophysiology and pharmacological techniques to examine the voltage-dependence and contrast-dependence of glutamate input to DSGCs arising from presynaptic bipolar cells. First, I observed that the proportion of AMPARs and NMDARs across the DSGC dendritic arbor appeared constant when probed with small light spots. Interestingly, however, NMDARs and AMPARs were recruited over distinct contrast ranges. NMDARs primarily mediated responses to low contrast stimuli, while AMPARs were recruited at higher contrast levels. This indicated that AMPARs and NMDARs do not necessarily reside within the same bipolar cell synapses. I also observed that NMDARs measured in pharmacological isolation could encode a wide range of stimulus contrast. Thus, the graded glutamate signals from bipolar cells appear to be effectively detected by NMDARs present on DSGCs. This was somewhat surprising because NMDARs are generally prone to saturation owing to their high affinity for glutamate. Furthermore, pharmacological investigation revealed that GluN2A and GluN2B subtypes of NMDARs contribute equally to the light-evoked responses, over the entire range of contrasts. Interestingly, currents triggered by spontaneous vesicle release from bipolar cells, which indicate the involvement of receptors directly opposite the release site, were almost entirely inhibited by the GluN2A antagonist. These findings point to a distinct localization of GluN2A and GluN2B in synaptic and extrasynaptic regions, respectively. My results suggest that NMDARs encode a large range of stimulus contrasts and are able to evade saturation by employing distinct bipolar cell types as well as incorporating a combination of GluN2A and GluN2B receptors positioned at specific distances from the vesicle release site. Together, my work provides novel insights into how AMPARs and NMDARs contribute to the ability of DSGCs to respond to diverse stimuli.
Introgression and subtle population structure in Copper and Quillback rockfishes
(2024) Sykes, Nathan; Owens, Gregory Lawrence
Genomic methods are increasingly being applied in fisheries to promote effective management and sustainability. Pacific rockfishes, genus Sebastes, inhabit inshore, shelf, and slope habitats along the North American west coast. Among these, Copper and Quillback rockfishes (abbreviated to Copper and Quillback) are closely related species known to hybridize, particularly within the Salish Sea in North America’s Pacific Northwest. Here, I investigate genetic population structure and introgression patterns in Copper and Quillback rockfishes from Alaska to California. Using low-coverage whole-genome resequencing (lcWGS) across a broad geographic range, I seek to (1) describe genetic differentiation between the rockfish species, (2) assess population structure within each species, (3) identify regions of the genome with unique patterns of differentiation between species, and (4) look for signatures of introgression in the genomes of both species. My analyses reveal that Copper exhibit higher levels of population differentiation compared to Quillback, especially between coastal and Salish Sea populations. In contrast, Quillback populations appear to be more panmictic, with lower overall differentiation. Several large haploblocks are found to be segregating between the species, with introgression patterns varying across genomic regions. These findings provide novel insights into the range-wide genetic structure of these species and highlight the role of genomic architecture in local introgression.
Proanthocyanidins in poplar roots - effects on mycorrhizal colonization and nitrogen uptake
(2024) Yamakawa, Daisuke; Hawkins, Barbara J.; Constabel, Carsten Peter
Proanthocyanidins (PAs), also known as condensed tannins, are widespread plant secondary metabolites, especially common in trees. PAs are known for their roles in plant defense and soil nutrient cycling, and their many applications in human medicine and diet. Although substantial research has focused on PA function in plant shoots, few studies have investigated their roles in roots. Some research indicates that PAs act as anti-fungal compounds, suggesting PAs in roots could negatively affect beneficial fungi in soils such as mycorrhizal fungi, which provide nutrients, including nitrogen (N), to host plants. Notably, the growth of the ectomycorrhizal (EcM) fungus Laccaria bicolor was inhibited in vitro by a purified extract of poplar PAs. Therefore, I aimed to evaluate the effects of PAs in roots on mycorrhizal colonization as well as on N uptake by colonized roots. Poplar (Populus. tremula x P. tremuloides) was chosen as the study species because poplars produce a wide range of phenolic compounds, including PAs. I utilized transgenic lines developed previously that have high and low PA concentrations in plant tissues, including roots. Plants from each line were equally divided into two treatment groups inoculated with either the EcM fungus L. bicolor or the arbuscular mycorrhizal (AM) fungus Rhizophagus irregularis, and one non-inoculated control group. Plants were grown in a sandwich culture system that allows co-culture of the mycorrhizal fungi and roots, or inoculated with the fungi in soil in a greenhouse experiment. Uptake of ammonium (NH4+) and nitrate (NO3−) by plant roots was measured using a microelectrode ion flux measurement system (MIFETM), and by 15N-labelling. Successful EcM colonization on poplar roots was confirmed in all the plant lines, while no AM structures were observed in the roots. Contrary to my prediction, the poplar line with low-PAs/phenolics in roots was less colonized by EcM fungi in both sandwich and soil culture. Additionally, plants from all lines inoculated with EcM fungi in sandwich culture system tended to have lower root PA concentrations. Although no significant difference in N uptake among plant lines or mycorrhizal treatments was observed, NH4+ uptake was greater than NO3− uptake. Understanding the effects of the interaction of root PAs and mycorrhizal fungi on mycorrhizal colonization and N uptake will contribute to our knowledge of the ecological and physiological impacts of PAs in the rhizosphere.
Oceanic atoll provides refuge for elasmobranchs amidst global declines and promotes opportunities to finance conservation
(2024) Zerr, Kaitlyn; Baum, Julia Kathleen
Sharks and rays (elasmobranchs) are charismatic megafauna that support healthy ecosystems and can serve as flagship species for marine conservation. Elasmobranchs tend to be highly mobile, mid- to high trophic level predators, with slow population growth rates that render them vulnerable to overexploitation. While many species have experienced widespread and ongoing population declines, some nations have recognized the value of elasmobranchs to the tourism industry. The Republic of Maldives has protected sharks and rays from exploitation within their national waters since 2014 because of the significant amount of revenue lost from the tourism industry when populations there began to show signs of overexploitation. However, local threats such as bycatch, entanglement in fishing gear, and unregulated tourism may continue to negatively impact populations, highlighting the need for additional conservation measures. Known as ‘Shark Island’, Fuvahmulah Atoll, a recently designated UNESCO Biosphere Reserve, has recently experienced a steep rise in dive tourism due to improved accessibility to, and awareness of, its abundant and diverse shark and ray megafauna. Although a marine protected area (MPA) has been designated at the southern end of the atoll, a management plan has not yet been developed and species-specific information is lacking. Furthermore, it is unclear if dive tourists are willing to contribute financially to help conserve the biodiversity upon which their tourism depends. Here, we sought to inform management plans and policy design by 1) quantifying elasmobranch assemblages on Fuvahmulah Atoll’s reefs and 2) examining tourists’ willingness to pay for increased conservation action on the atoll. In Chapter 2, we deployed remote timelapse cameras at three shallow fore reef sites and collected images on 63 days over a 6-month period. From a total of 1,629,756 images, we calculated the occurrence and relative abundance within days and hours to assess spatial and temporal variations in elasmobranch visitation to the sites. Sharks and rays were captured on 72% of hours and 95% of days, with the highest number of occurrences recorded at the site within an MPA, Farikede, followed by Kedevari and Hudhekede. Both reef sharks and apex sharks were represented, with whitetip reef sharks, pelagic threshers, grey reef sharks, tiger sharks, and silvertip sharks, representing the most frequently observed species. We show that Farikede MPA is a hotspot for reef sharks and tiger sharks. However, Kedevari appears to be an ecologically significant site for pelagic threshers. In Chapter 3, we conducted stated preference surveys with tourists visiting Fuvahmulah to assess tourists’ willingness to pay a one-time “Reserve” entrance fee, the factors that influence the value of the fee, and their preferences for conservation measures proposed by the community. Virtually all (97%) tourists were supportive of paying a one-time reserve entrance fee, with an average fee of US$58 per person. Tourists with more positive environmental attitudes, those more committed to dive tourism (higher skill levels and more frequent trips), and those who encountered specific shark species (tiger sharks or pelagic threshers) in Fuvahmulah were willing to pay higher entrance fees. Visitors to Fuvahmulah Atoll highly value marine conservation, and their financial support creates unique opportunities to safeguard biodiversity and ensure the sustainability of the tourism industry. Increasing our understanding of the biological community while exploring avenues to finance conservation can provide opportunities to create informed and comprehensive management plans. While many elasmobranch populations continue to experience global declines, protected and well-managed sites may increase resilience on a global scale.
Improving our understanding of vertebrates in nutrient recycling and ecological stoichiometry
(2024) May, Emily M.; El-Sabaawi, Rana
Nutrient-rich, large, long-lived, and mobile, vertebrates may uniquely impact nutrient recycling and thus ecosystem function by storing copious nutrients within their bodies, by producing large quantities of waste, and by transporting nutrients long distances within and across ecosystems. Currently, vertebrates face myriad threats, leaving many ecosystems to face a future with reduced vertebrate biomass and diversity; understanding how vertebrates affect nutrient cycles thus provides valuable insight into how vertebrate extinctions will impact ecosystems. Broadly, I characterize variation in how vertebrates store phosphorus (P) within their bodies and recycle P from their diets in their excreted and egested wastes. To accomplish this, I link bone investment, bodily elemental content, and waste production. Bone, a P-rich tissue (mean of ~12%) unique to vertebrates, can alter vertebrate-driven nutrient recycling both by increasing P storage within vertebrate bodies and by changing P demand and thus P release in waste. Given this, my dissertation has three goals: (1) quantify how vertebrates vary in bone content and whole-body %P, (2) determine how this variation affects dietary intake and waste production, and (3) evaluate how bone may affect P demand differently from other P-rich bodily components. To fully characterize this, I used ecological stoichiometry (ES), a framework that uses mass-balance to conceptualize organismal and ecological processes, including nutrient uptake and processing by animals. I therefore begin my dissertation by developing methods to measure all factors effectively and simultaneously, which is rarely achieved in current literature. Using these methods, I then performed a field study to examine how intraspecific bone variation in the threespine stickleback (an evolutionary model fish species with well-characterized bone variation) affected whole-body %P, dietary %P, and P release in excreta and egesta. ES predicts that bone increases whole-body %P and should therefore increase P demand and decrease P release. Counter to these predictions, I found that although stickleback with more bone indeed had higher whole-body %P, bone did not clearly impact P demand. Stickleback with more bone showed similar diets, nutrient absorption, and egestion to those with less bone. Additionally, stickleback with more bone excreted more P, perhaps implying that bone mitigates P demand rather than causing it. More broadly, I found considerable variation in bone, whole-body %P, and waste production within and across sites, most of which was unexplained by size, sex, or environmental characteristics. Bone also causes interspecific and ontogenetic differences. In a systematic review of vertebrate elemental content, I found whole-body %P ranging from 0.39 – 6.91% P, suggesting strong bone variation across taxa (interspecific) and life stages (intraspecific). Given my previous findings, this variation may impact P demand and release in unexpected ways. Thus, I finish by integrating osteological and stoichiometric literature to examine how bone’s unique physiology affects its relationship with P demand and release. While ES implicitly assumes all tissues impact demand equally, bone’s unique characteristics change how it affects elemental demand. Primarily, bone’s ability to self-destroy and provide mineral nutrients to the rest of the body allows bone to directly mitigate a vertebrate’s increased P or calcium demands. This may make vertebrates with more bone more resilient to dietary P limitation, rather than the opposite. Ideally, future research will build on these findings to improve our overall understanding of vertebrate-driven nutrient recycling.
Egg parasitoids and predators of the douglas-fir tussock moth, Orgyia pseudotsugata (Lepidoptera : Lymantriidae), in British Columbia
(1995) Young, David Steven
Field collected egg masses of the Douglas-fir tussock moth, Orgyia pseudotsugata (McDunnough), were reared to identify the species of egg parasitoids occurring in British Columbia, investigate the seasonal oviposition activity of the parasitoids, and determine the proportion of egg mortality caused by each species. Telenomus californicus Ashmead was the dominant species in all of the study areas which included the Kamloops, Ashcroft, Vernon, and Hedley areas. Telenomus dalmani (Ratzeburg) was also reared but contibuted very little to the overall egg parasitism. The combined parasitism by these species was generally very low and ranged from Oto 20.9% of eggs collected in the fall and from 0.05 to 17.7% of eggs collected in the spring. Evidence suggests, however, that parasitism by Telenomus spp. may reach from ca. 52% to greater than 90%. Parasitism by these species of the egg masses collected in the spring was over twice as high as that for eggs collected in the fall at the same six sites. The highest levels of parasitism generally occurred at younger infestations where egg masses were relatively scarce but the relationship between percent parasitism to the estimated age of infestations was not significant. All of the infestations occurred within either the Ponderosa Pine (PP) or interior Douglas-fir (IDF) biogeoclimatic zones, but no relationship could be established between these zones and the observed levels of parasitism. Members of the Trichogramma minutum complex were only responsible for parasitizing O to 7% of the eggs at sites and the overall parasitism by all others species was less than 1 %. A key for identifying common egg parasitoids of Douglas-fir tussock moth in B.C. was created. Naturally-occurring and artificially-stocked egg masses were used to quantify the mortality due to predation on overwintering egg masses in the Kamloops and Ashcroft areas. In the Ashcroft area, 1.9% of artificially-stocked egg masses was completely removed and 2.3% of the naturally-occurring egg masses was missing. In the Kamloops area 15.0% of the artificially-stocked egg masses was completely removed and 12.5% of the naturally-occurring egg masses was missing. The infestations at the study sites in the Kamloops area were smaller and had much lower densities of Douglas-fir tussock moth than those in the Ashcroft area. An investigation of predation on naturally-occurring egg masses within the crown of Douglas-fir indicated that the level of predation among the lower, middle and upper crown level was not significantly different. However, evidence also indicates that avian predators will feed more in the crown level which contains the largest number of egg masses. The mountain chickadee, Parus gambeli Ridgeway, red-breasted nuthatch, Sitta canadensis L., and dark-eyed junco, Junco hyemalis L. are implicated as the primary predators.
Molecular characterization of the Neodiprion abietis nucleopolyhedrovirus
(2002) Young, Aaron Michael
Baculoviruses are a large, diverse family of viruses that are pathogenic for Arthropods, particularly members or the Order Insecta. These viruses are comprised of large enveloped rod-shaped capsids that contain supercoiled, double-stranded DNA genomes. Baculoviruses are of particular interest because of their use as gene expression vectors and insect biological control agents. Most of the information currently available on baculoviruses comes from studies of the Autographa californica nucleopolyhedrovirus and closely related species. Very little information is available on baculoviruses from other insect Orders, including Hymenoptera. The balsam fir sawfly (Neodiprion abietis, Order:Hymenoptera) is a native insect species that is currently causing severe, annual damage to economically valuable balsam fir forests in eastern Canada. Due to environmental regulations, standard chemical pesticides cannot be used to control this pest and as a result, biological control agents have been proposed as a potential alternative. A nucleopolyhedrovirus (NPV) has recently been isolated from N abietis and has been shown to be able to control balsam fir sawfly population outbreaks in controlled field experiments, however, before the N abietis nucleopolyhedrovirus (NeabNPV) can be registered for use as a biological control agent, research must be conducted to characterize the virus. I have partially characterized NeabNPV at the nucleotide and protein sequence levels and have concluded that NeabNPV is highly diverged from other members of the Family Baculoviridae. DNA libraries were constructed for NeabNPV using sheared viral genome fragments and HindIII restriction fragments. An EcoRI restriction library was obtained from the Canadian Forestry Centre, Atlantic Division, and was also included in this study. Analysis of the restriction endonuclease profiles obtained for NeabNPV indicate that NeabNPV has a genome approximately 94.7 kilobase pairs in size. Nucleotide sequence data obtained from these DNA libraries was used to perform comparative sequence analyses and demonstrated that NeabNPV contains many putative baculovirus gene homologues. From the sequence data, four putative complete open reading frames (ORF) were predicted: odv-e56, vlf-1, p74, and polh. The putative polyhedrin gene homologue was amplified from the NeabNPV genome and sequenced. Analysis of the polyhedrin gene sequence showed that it was 738 nucleotides long and encoded a protein of a predicted molecular weight of 29 .5 kDa. The promoter region of the gene was determined to contain two copies of the baculovirus specific late transcription motif, TAAG. The NeabNPV polyhedrin gene is highly diverged from Lepidopteran NPVs and GVs (Granulovirus) and shares its highest sequence identity with the polyhedrin gene of the Hymenopteran baculovirus Neodiprion sertifer nucleopolyhedrovirus. Phylogenetic analyses of several putative NeabNPV gene homologues suggested that NeabNPV is highly diverged from the previously described Group I and Group II NPVs and appears in a unique evolutionary clade separate from both the Lepidopteran NPVs and GVs. Phylogenies which included the mosquito (Order: Diptera) baculovirus Culex nigripalpus nucleopolyhedrovirus (CuniNPV) and that used the GV s as a sister outgroup to the NPV s placed N eabNPV and CuniNPV into a unique evolutionary clade within the NPV group, separate from the Group I and Group II NPV s. I have also investigated NeabNPV at the protein level and have putatively identified the major nucleocapsid protein, VP39. Structural proteins from budded (BV) and occlusion-derived virions (ODY) were separated on polyacrylamide gels using SDS PAGE and several well-defined proteins were isolated and partially sequenced. The amino acid sequence data was used to perform comparative sequence analyses against our NeabNPV DNA libraries and determined that the genomic DNA library contained several putative overlapping partial vp39 sequences. These sequences were assembled to create an 864 nucleotide long, partial NeabNPV vp39 sequence. Analysis of the inferred amino acid sequence indicated that the NeabNPV VP39 protein shares the most identity to the GVs, but is most similar to the NPVs. The partial VP39 protein demonstrates a predicted secondary structure and hydrophilic profile that is conserved among the Baculoviridae.
Infectivity of Agrobacterium tumefaciens and proteins of crown gall tumors in Helianthus annuus
(1985) Wu, Hsiao-Chiang
A qualitative and quantitative study of the infectivity of Agrobacterium tumefaciens on sunflowers (Helianthus annuus) and other species (peas, beans and corn) was made by measuring the frequency of tumor induction in the greenhouse. According to the results, sunflowers and peas were sensitive to tumor induction . The effects of concentration of agrobacteria, and flowering stage or age of sunflower on tumor induction frequency were significant. After flowering, sunflower was resistant to tumor induction. This could be an aging effect. The effects of bacteria culture time after 2 days, and plant age before anthesis on tumor induction were not significant. But plant age may have had some effect on tumor development; the younger the plant, the more rapid the tumor development. The effect of inoculation position on the sunflower stem on tumor induction was not significant, but no tumors could be induced on leaves of any plants studied. The light and temperature differences of plant growth conditions between the greenhouse and growth chambers were significant on tumor development . In greenhouses, tumors developed more slowly than in growth chambers. No tumor was induced on maize or on two cultivars of beans (Phaseolus vulgaris cv. Improved Tendergreen and cv. Kentucky Wonder Green). Soluble proteins of crown gall tumors in Helianthus annuus were analyzed by methods of SDS-Polyacrylamide gel electrophoresis and spectrodensitometry. The chlorophyll-containing complexes were the same in tumor and control tissues. It was found that the migration distance of these complexes was negatively affected by the sample volume loaded. Sometimes a good separation of these complexes was not obtained at the same time as good separation of soluble proteins. A sample buffer with 5% SDS and 8 M urea was good for preventing aggregation of proteins from sunflowers which probably contained a high amount of interfering compounds , and increased the resolving power of SDS-PAGE.
Furocoumarin production by pastinaca sativa and apium graveolens
(1988) Woodcock, Paul Vincent
The furocournarins are a group of secondary metabolites, produced from the same precursors as the flavonoids in Pastinaca sativa (parsnip), and Apium graveolens (celery). The compounds help protect plants from disease and herbivory. The furocournarins produced by these plants are capable of intercalating into the double helix of DNA. If excited by ultra violet (UV) irradiation they are capable of forming mono- and di-adducts with pyrimidine bases, especially thymine. The photo-adducts have been shown to be toxic and mutagenic in both prokaryotic and eukaryotic cells. This property makes the furocournarins, in the presence of UV light, an effective deterrent against fungal, bacterial, and insect attack. The compounds also pose some problems for humans handling plant products containing furocournarins. The aims of this work are to look at the patterns of furocournarin production during the first year of growth of P. sativa and~. graveolens. Changes in the levels of production of these molecules will affect the ability of the plants to defend themselves against opportunistic attack. The furocournarins were extracted from fresh plant tissue with ethyl acetate. The compounds were qualitatively detected by biological photo-assay using a DNA repair deficient Escherichia coli, and quantification was done by high pressure liquid chromatography. P. sativa produces seven furocoumarins during the first year of growth. Seedlings produce the highest levels of furocoumarin. Seedlings require the most protection, as any damage to the small plants will probably kill them. Between 19 and 55 days after planting there is a reduction in furocoumarin production, which remains depressed until after 132 days after planting. At this stage the plants are growing most actively. Plants may reduce furocoumarin production to prevent damage to the mitotically active cells. After 132 days after planting furocoumarin production in leaves and petioles rises, but falls in roots. Protection of the established photosynthetic tissue by the production of substantial amounts of furocoumarin will ensure the overwintering roots have sufficient nutrients to grow in the next year. Roots at this stage of development are unlikely to benefit from the presence of furocoumarins. The roots are firmly established underground and, in the absence of UV irradiation, the furocoumarins would have little or no inhibitory effect on invading pathogens. A. graveolens produces much lower concentrations of furocoumarin than P. sativa. Only three furocoumarins were detected in A. graveolens, 5-methoxypsoralen and 8-methoxypsoralen which are photoactive, and isopimpinellin which is not. No clear patterns of furocoumarin production emerged either between tissues or as the plants age. Levels are not high enough to clearly deter insect feeding or inhibit pathogen attack. It seems likely that A. graveolens would have to rely on the defence mechanisms, which would increase furocoumarin production, to prevent successful microbial attack.
Some aspects of the reproductive biology of Fusitriton oregonensis (Redfield) (Gastropoda, Prosobranchia)
(1976) Williams, Daphne Eiri
Little is known of t he reproductive biology of the prosobranch Fusitriton oregonensis (Redfield). Therefore this thesis describes the morphology and histology of the male and female reproductive tracts, the spermatogenesis of all types of sperm and their structure. Both the male and female reproductive systems are in an advanced mesogastropod state, approaching the neogastropod condition. Primitive features of the male system are an open prostate gland and an open sperm groove extending along the phallus. The least advanced feature of the female system is the seminal receptacle which is merely a dilation of the distal portion of the oviduct. Three types of sperm develop in the testes of F. oregonensis continually throughout the year. Maximum production however, occurs during February, March and April. Two sperm lines develop, (1) the eupyrene or fertilizing sperm and (2) the apyrene anucleate sperm, of which there are two types, the carrier and the lancet. Development of eupyrene sperm is typical but complex; one spermatogonium produces four haploid sperm after two meiotic divisions. In contrast, development of apyrene is atypical and direct; one spermatogonium produces one sperm. The nucleus of the spermatogonium fragments and degenerates within the cell. Cellular differentiation is not complex. The most numerous and active of all three types are the eupyrene sperm. They are long and filamentous, similar to other gastropod sperm. The acrosome is conical and hollow. A rod extends through the subacrosomal space which also contains a subacrosomal granule. Posterior to the acrosome is a modified centriole from which extends an axoneme of the standard 9+2 pattern. The nucleus is cylindrical, encircling the axoneme distal to the acrosome. Distal to the nucleus is a mitochondrial spiral also encircling the axoneme and further distal is the glycogen region. Grouped glycogen rosettes having a characteristic pattern extend to the end of the tail piece where the axoneme emerges free for a short distance. The slow-moving carrier apyrene sperm is short and fusiform. Through its centre runs a core of axonemes of standard configuration, each of which extends from an anterior modified centriole. Encircling the core are tightly packed large droplets containing acid mucopolysaccharide complexed with protein. Dispersed amongst these are glycogen rosettes and a few mitochondria. Fifty or more eupyrene sperm attach to one carrier sperm forming a spermatozeugma. Carrier sperm are probably a nutrient source for eupyrene sperm. There may be other less obvious functions for the spermatozeugrnata. Lancet apyrene sperm are long and so named because of their shape. They are less active than the carrier sperm and eupyrene sperm do not attach to them. Several standard axonemes arise from apically placed modified centrioles and extend beneath the plasmalemma distally to the end of the sperm; single microtubules lie in a similar position between the axonemes. Disposed anteriorly in the cytoplasm are mitochondria and numerous small droplets containing acid mucopolysaccharides complexed with protein. Posterior are several large mucus - containing droplets. Scattered throughout the cytoplasm are glycogen rosettes. The roles of the lancet sperm are less obvious than those of the carrier. After copulation, the three types of sperm are stored for a short time in the female copulatory bursa. Most eupyrene sperm move to the seminal receptacle for some time prior to fertilization. Apyrene sperm remain in the viscous fluid in the copulatory bursa. Lancet sperm appear to begin degeneration and entrap any other sperm remaining in the bursa, producing plasmodial-like formations. The significance of this is uncertain.
Characterization of the multigene family encoding endopolygalacturonase in the basidiomycete Chondrostereum purpureum
(2001) Williams, Holly Louise
Chondrostereum purpureum is a white-rot basidiomycete fungus which is being developed as a biocontrol agent of hardwoods for use in reforestation sites and hydroelectric rights-of-ways. It produces several plant cell wall-degrading enzymes that are suspected virulence factors, including endopolygalacturonase (endoPG). To search for new endoPG genes in C. purpureum, degenerate oligonucleotide primers were designed based on conserved regions of seventeen ascomycete endoPG genes and two published endoPG sequences from C. purpureum. These primers were used to amplify endoPG gene fragments from C. purpureum 2128u genomic DNA. Fifty-six of the amplification products were analyzed by sequence determination or restriction digestion to reveal segments of three previously uncharacterized endoPG genes, as well as epgA, an endoPG gene sequenced from C. purpureum 2128u. The three new genes were named epgB, epgC, and epgD, and the full length sequences of two copies of epgB (epgB1 and epgB2) were retrieved from a genomic library of C. purpureum 2128u. The identities between the deduced polypeptide sequences for epgA , epgB1, epgC and epgD ranged from 61.8% to 80.0%. The two epgB genes shared 97.6% nucleotide identity and 97.1 % amino acid identity, with the majority of differences between them near the 3' ends of the genes. Phylogenetic analysis of these five basidiomycete endoPGs, seventeen ascomycete endoPGs, four ascomycete exoPGs, two bacterial endoPGs, and two bacterial exoPGs separated the C. purpureum endoPGs into their own monophyletic clade; whereas the endoPGs from ascomycete species having multiple endoPGs were divided between different monophyletic groups within the ascomycete endoPG clade. This split between the ascomycete and basidiomycete endoPGs suggests the two fungal phyla diverged before the duplication of existing endoPG genes. Mechanisms regulating the expression of the endoPG genes in C. purpureum were examined by northern analyses using mycelia grown in media with different carbohydrate sources. The epgA gene was expressed at high levels when glucose, sucrose or pectin was used as the carbon source; whereas both epgB genes, epgC, and epgD were expressed at low or non-detectable levels on all media types. The expression of epgA appeared to be constitutive and not repressed by simple sugars, suggesting EPGA may be the most important of the five endoPGs in the plant cell wall degradation caused by C. purpureum.
Life histories and post-glacial origins of tundra caddisflies (Trichoptera) from the Tuktoyaktuk Peninsula, Northwest Territories
(1984) Winchester, Neville Norman
Life histories, species composition and post-glacial origins of Trichoptera from the Tuktoyaktuk Peninsula, Northwest Territories were examined. Nineteen species were identified while eight others could not be identified to species. Eighty-two percent of this fauna represented new Canadian arctic reports and all species represented Nearctic range extensions. Sphagnophylax meiops, gen. et sp. nov. was discovered. Time available for insect growth in arctic regions is short and in this study was confined to early June - late September. Life cycles were completed in temperatures that consistently remained above 0c. For the remainder of the year complete freezing of the stream and shallow areas of the surrounding drainage basin occurred. Trichoptera overwintered in several larval instars and survived ice encasement. These larvae were probably freezing tolerant, although more than one mechanism may exist to allow survival at sub-zero temperatures. Thawing, which began in mid-May, was completed by mid-June and created a mosaic of flooded lowland marsh. This continuous littoral zone dominated by rooted macrophytes provided large areas for caddisfly aggregations. A small portion of the total fauna resided in the stream channel. This limited stream habitat contributed to the exclusion of strict lotic Trichoptera. Life history information for 10 of 19 species suggested that all species have a one year life cycle. Adult emergence coincided with the onset of drought. Developmental rates and number of instars were constant among all species. Rates of increase varied between 1.13 and 1.44. All rates agreed with Dyar's Rule except that of Sphagnophylax meiops. Three patterns of flight period were recognized, defined on the basis of flight duration. Flight periods did not show a progression towards short and highly synchronized emergence with increased latitude. The systematic and biogeographic relationships within the Trichoptera of northwestern North America were affected by past glacial events. The post-glacial origin of this fauna was composed of three groups that included Trichoptera that spent the glaciation: (1) in Beringia, (2) south of the ice sheets, or (3) in both areas. The Beringian element was subdivided into 3 groups based on species distributional patterns. Group A was found only in Beringia (in North America). Group B was Beringian and widespread in North America but absent in the Palearctic. Group C included Amphi-Beringian species with Nearctic and Palearctic distributions. Populations may have been split and were present in both areas simultaneously. The probable post-glacial sources of this fauna were: Beringia, 47%; south of the ice sheets, 23.5%; and both of these areas, 29.5%. The composition of the Beringian elements including those species thought to have re-colonized from both areas was: Group 1, 31%; Group 2, 31%; and Group 3, 38%. This study notes that a diverse caddisfly assemblage exists in the low arctic. Species survive extended cold periods, periods of drought, and are able to complete their life cycles in one year. Beringia is considered an important source area contributing to the observed species diversity.
The functional morphology of the uropod stretch receptor of the sand crab Emerita analoga : including a comparison with the uropod stretch receptor of the squat lobster Munida quadrispina
(1988) Wilson, Linda Jane
While much is known about the response characteristics and the central connections of crustacean primary afferents, the mechanism of stimulus transduction in stretch receptors remains enigmatic. I studied the morphology of a basal joint proprioceptor in two Anomura (Hippidae, Galatheidae) in order to better understand the mechanical aspects of the transduction process (the other aspects depend on the electrochemical properties of the membrane). The uropod stretch receptor (USR) complex in the sand crab Emerita analoga (Stimpson 1857) consists of an elastic strand innervated by four giant, nonspiking, mechanoreceptive neurons (NSRs) with central somata and a separate, parallel muscular strand innervated by two groups of neurons of unknown modality (Paul, 1972). Each of the NSRs has three morphologically distinct zones in the periphery. The Zone of Dendrite Entry for each NSR begins outside the strand at the first bifurcation of the dendrite into two primary branches which enter the strand at acute to right angles as thick ( 40 to 60µm) cylinders and immediately turn rostrally and caudally along the long axis of the strand and extend into the strand where further branching occurs. The Zone of Branching consists of 4 to 15 m diameter dendritic branches within the strand. Tiny (0.1-0.5 µm) cylindrical processes (dendritic tips) arise directly from all levels of this zone so that even the largest branches appear to be covered in the fine dendritic "hairs" of the Zone of Dendrite Termination. Each pair of branches is divided by a rod of extracellular matrix (ECM) running parallel to the long axis of the strand. These vacuolated strings are fusiform in shape and extend for the length of the dendritic branch with which each string is associated. Dendritic tips project into the strings and are probably the site of mechanosensory transduction because they are in direct contact with the ECM of the vacuolated string which is compressed by strand-stretching. Fibres in the ECM of the capsule and vacuolated strings of the elastic strand appear to belong to a special class of 'invertebrate elastic fibres' described by Elder and Owen (1967) and give the strand its resilience. Cross-sectional profiles of dendritic tips are significantly larger but significantly less numerous in stretched than in relaxed receptors. I propose a model in which distal tips are compressed until they are too small to be recognized in stretched strands. The large profiles are the proximal tip regions which have expanded by hydrostatic pressure. Like Emerita, the squat lobster, Munida quadrispina (Benedict 1902) has a USR complex consisting of parallel elastic and muscular strands. The strands are closely opposed to one another and lie in a single, ventral plane rather than running dorso-ventrally as they do in Emerita. The receptor complex receives its innervation from the receptor nerve which contains 10-13 profiles whose signal characteristics are unknown. Two of the smallest appear to innervate the receptor muscle, the remainder the elastic strand. The one or two largest profiles (10-20 µm), upon entering the strand transversely, turn longitudinally, and become associated with vacuolated strings into which they send tips as do the four NSRs in Emerita. Homologies between the two USRs and other basal joint proprioceptors are suggested and some functional and evolutionary consequences of USR morphology are discussed.
Biochemical responses based on cytochrome P450 induction in chinook salmon (Oncorhynchus tshawytscha) exposed to bleached kraft mill effluent on the Fraser River
(1996) Wilson, Joanna Yvonne
Juvenile chinook salmon were collected from sites on the upper Fraser River downstream of bleached kraft pulp mills and municipal outfalls. Ethoxyresorufin-O-deethylase activity (EROD), CYP I Al density, and DN A adduct concentrations were measured in liver tissue. Liver histopathology was performed. Polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and polychlorinated biphenyls (PCBs) were measured in carcasses. Polyaromatic hydrocarbon (PAH) metabolites were measured in bile. Biochemical, but not histopathological, responses were significantly different from those in controls at nearly all sites. Biochemical responses were not correlated with any of the contaminants analyzed. Fish sampled closest to effluent discharge showed the weakest responses. In fish experimentally exposed to effluent, significant increases in biological effects were seen at 2% (and higher) effluent concentrations. These results indicate that fish at this site may not be exposed to effluent concentrations previously thought, perhaps suggesting that chinook are mobile during winter months. Biological responses are not caused by the organic contaminants measured.

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