Biological and Physical Factors Affecting the Natural History and Evolution of Encapsulated Development

The evolution of reproductive strategies involves a complex calculus of costs and benefits to both parents and offspring. Many marine animals produce embryos packaged in tough egg capsules or gelatinous egg masses attached to benthic surfaces. While these egg structures can protect against environmental stresses, the packaging is energetically costly for parents to produce. In this series of studies, I examined a variety of ecological factors affecting the evolution of benthic development as a life history strategy. I used marine gastropods as my model system because they are incredibly diverse and abundant worldwide, and they exhibit a variety of reproductive and developmental strategies.

The first study examines predation on benthic egg masses. I investigated: 1) behavioral mechanisms of predation when embryos are targeted (rather than the whole egg mass); 2) the specific role of gelatinous matrix in predation. I hypothesized that gelatinous matrix does not facilitate predation. One study system was the sea slug Olea hansineensis, an obligate egg mass predator, feeding on the sea slug Haminoea vesicula. Olea fed intensely and efficiently on individual Haminoea embryos inside egg masses but showed no response to live embryos removed from gel, suggesting that gelatinous matrix enables predation. This may be due to mechanical support of the feeding predator by the matrix. However, Haminoea egg masses outnumber Olea by two orders of magnitude in the field, and each egg mass can contain many tens of thousands of embryos, so predation pressure on individuals is likely not strong. The second system involved the snail Nassarius vibex, a non-obligate egg mass predator, feeding on the polychaete worm Clymenella mucosa. Gel neither inhibits nor promotes embryo predation for Nassarius, but because it cannot target individual embryos inside an egg mass, its feeding is slow and inefficient, and feeding rates in the field are quite low. However, snails that compete with Nassarius for scavenged food have not been seen to eat egg masses in the field, leaving Nassarius free to exploit the resource. Overall, egg mass predation in these two systems likely benefits the predators much more than it negatively affects the prey. Thus, selection for environmentally protective aspects of egg mass production may be much stronger than selection for defense against predation.

In the second study, I examined desiccation resistance in intertidal egg masses made by Haminoea vesicula, which preferentially attaches its flat, ribbon-shaped egg masses to submerged substrata. Egg masses occasionally detach and become stranded on exposed sand at low tide. Unlike adults, the encased embryos cannot avoid desiccation by selectively moving about the habitat, and the egg mass shape has high surface-area-to-volume ratio that should make it prone to drying out. Thus, I hypothesized that the embryos would not survive stranding. I tested this by deploying individual egg masses of two age classes on exposed sand bars for the duration of low tide. After rehydration, embryos midway through development showed higher rates of survival than newly-laid embryos, though for both stages survival rates over 25% were frequently observed. Laboratory desiccation trials showed that >75% survival is possible in an egg mass that has lost 65% of its water weight, and some survival (<25%) was observed even after 83% water weight lost. Although many surviving embryos in both experiments showed damage, these data demonstrate that egg mass stranding is not necessarily fatal to embryos. They may be able to survive a far greater range of conditions than they normally encounter, compensating for their lack of ability to move. Also, desiccation tolerance of embryos may reduce pressure on parents to find optimal laying substrata.

The third study takes a big-picture approach to investigating the evolution of different developmental strategies in cone snails, the largest genus of marine invertebrates. Cone snail species hatch out of their capsules as either swimming larvae or non-dispersing forms, and their developmental mode has direct consequences for biogeographic patterns. Variability in life history strategies among taxa may be influenced by biological, environmental, or phylogenetic factors, or a combination of these. While most prior research has examined these factors singularly, my aim was to investigate the effects of a host of intrinsic, extrinsic, and historical factors on two fundamental aspects of life history: egg size and egg number. I used phylogenetic generalized least-squares regression models to examine relationships between these two egg traits and a variety of hypothesized intrinsic and extrinsic variables. Adult shell morphology and spatial variability in productivity and salinity across a species geographic range had the strongest effects on egg diameter and number of eggs per capsule. Phylogeny had no significant influence. Developmental mode in Conus appears to be influenced mostly by species-level adaptations and niche specificity rather than phylogenetic conservatism. Patterns of egg size and egg number appear to reflect energetic tradeoffs with body size and specific morphologies as well as adaptations to variable environments. Overall, this series of studies highlights the importance of organism-scale biotic and abiotic interactions in evolutionary patterns.

The Kyoto School and Confucianism: a Confucian reading of the philosophy of history and political thought of Masaaki Kosaka

This dissertation examines the philosophy of Masaaki Kōsaka (1900-1969) from the East Asian perspective of Confucianism, which I believe is the most appropriate moral paradigm for comprehending his political speculations. Although largely neglected in post-war scholarship, Kōsaka was a prominent member of the Kyoto School during the 1930s and 40s. This was a group of Japanese thinkers strongly associated with the philosophies of Kitarō Nishida and Hajime Tanabe. Kōsaka is now best known for his participation in the three Chūō Kōron symposia held in 1941 and 1942. These meetings have been routinely denounced by liberal historians due to the participants’ support for the Pacific War and the Co-Prosperity Sphere. However, many of these liberal portrayals have failed to take into account the full extent of the group’s resistance to the military junta of Hideki Tōjō. Adopting the methods and techniques of the empirical disciplines of academic history and Orientalism, I develop an interpretative framework that is more receptive to the political values that mattered to Kōsaka as a Confucian inspired intellectual. This has necessitated the rejection of moral history, which typically prioritises modern liberal values brought a priori to the historical record of wartime Japan, as well as recognition of the different ontological foundations that inform the unique political theories of the East Asian intellectual tradition. Reinforced by the prior research of Michel Dalissier and Graham Parkes, as well as my own reading of the Confucian canon, I adopt David Williams’s thesis of ‘Confucian Revolution’ as my principle schema of interpretation. This, I believe, is better able to reconcile Kōsaka’s support for the war with his strong condemnation of the imperialist practices of the Japanese military. Moreover, acknowledging the importance of Confucianism allows us to fully appreciate Kōsaka’s strong affinity for Kant’s practical metaphysics, Hegel’s political philosophy and Ranke’s historiography.

The effects of trans-generational exposure to ocean warming and acidification on life history and physiological traits in a marine polychaete

Human-assisted, trans-generational exposure to ocean warming and acidification has been proposed as a conservation and/or restoration tool to produce resilient offspring. To improve our understanding of the need for and the efficacy of this approach, we characterised life history and physiological responses in offspring of the marine polychaete Ophryotrocha labronica exposed to predicted ocean warming (OW: + 3 °C), ocean acidification (OA: pH -0.5) and their combination (OWA: + 3 °C, pH -0.5), following the exposure of their parents to either control conditions (within-generational exposure) or the same conditions (trans-generational exposure). Trans-generational exposure to OW fully alleviated the negative effects of within-generational exposure to OW on fecundity and egg volume and was accompanied by increased metabolic activity. While within-generational exposure to OA reduced juvenile growth rates and egg volume, trans-generational exposure alleviated the former but could not restore the latter. Surprisingly, exposure to OWA had no negative impacts within- or trans-generationally. Our results highlight the potential for trans-generational laboratory experiments in producing offspring that are resilient to OW and OA. However, trans-generational exposure does not always appear to improve traits, and therefore may not be a universally useful tool for all species in the face of global change.

Essays on Firm Heterogeneity with Empirical Applications in Economic History and Agricultural Economics

This thesis uses models of firm-heterogeneity to complete empirical analyses in economic history and agricultural economics. In Chapter 2, a theoretical model of firm heterogeneity is used to derive a statistic that summarizes the welfare gains from the introduction of a new technology. The empirical application considers the use of mechanical steam power in the Canadian manufacturing sector during the late nineteenth century. I exploit exogenous variation in geography to estimate several parameters of the model. My results indicate that the use of steam power resulted in a 15.1 percent increase in firm-level productivity and a 3.0-5.2 percent increase in aggregate welfare. Chapter 3 considers various policy alternatives to price ceiling legislation in the market for production quotas in the dairy farming sector in Quebec. I develop a dynamic model of the demand for quotas with farmers that are heterogeneous in their marginal cost of milk production. The econometric analysis uses farm-level data and estimates a parameter of the theoretical model that is required for the counterfactual experiments. The results indicate that the price of quotas could be reduced to the ceiling price through a 4.16 percent expansion of the aggregate supply of quotas, or through moderate trade liberalization of Canadian dairy products. In Chapter 4, I study the relationship between farm-level productivity and participation in the Commercial Export Milk (CEM) program. I use a difference-in-difference research design with inverse propensity weights to test for causality between participation in the CEM program and total factor productivity (TFP). I find a positive correlation between participation in the CEM program and TFP, however I find no statistically significant evidence that the CEM program affected TFP.

Narratives Around Iberian Culture at Valencia Museums and Archaeological Sites: From Official Discourses to Social Perceptions

Museums and archaeological sites are considered the most authoritative places for talking about the past and the heritage from a scientific perspective. In fact, visitors assume their discourses as reliable and indisputable. In spite of that, professionals of archaeology must critically analyse the production of narratives at heritage sites, since they often reflect social, political and identity issues related to the present-day realities. The aim of this paper is to study official and popular discourses about the Iberian culture (Iron Age) collected in museums and archaeological sites from Valencia region.

Sentimental Identity, History and Politics in Daniel Cortezón’s "A vila sulagada"

The novels of Daniel Cortezón, which have not attracted as much critical attention as his theatrical productions, are of contemporary interest as they develop his ideas on identity, history and politics. The purpose of this article is to show, through an analysis of the complex arrangement of the above three concepts, how A vila Sulagada is a metaphor for the historical failure of Galicia.

Temporalization of History and Methodological Perspectivism

This essay aims to explore the issue of methodologic perspectivism in Kosselleck’s thought considering as cornerstone the concept of temporalization. The first section links the concepts of temporalization and secularization introducing beforehand philosophies of the history from Sattelzeit time. Then the text focuses on reconstructing the notion of temporalization based on an emerging tension between the language and the reality it describes. This article concludes bringing up the notion of ficcionality as a key element in Koselleck’s theory of history making up for the methodological deficits after this tension. The unifying thread of this essay is that the theoretical project of a conceptual history it is not only an analysis method but mainly a theory of modernity.

Combining histology, stable isotope analysis and ZooMS collagen fingerprinting to investigate the taphonomic history and dietary behaviour of extinct giant tortoises from the Mare aux Songes deposit on Mauritius

Taphonomic research of bones can provide additional insight into a site's formation and development, the burial environment and ongoing post-mortem processes. A total of 30 tortoise (Cylindraspis) femur bone samples from the Mare aux Songes site (Mauritius)were studied histologically, assessing parameters such as presence and type of microbial alteration, inclusions, staining/infiltrations, the degree of microcracking and birefringence. The absence of microbial attack in the 4200 year old Mare aux Songes bones suggests the animals rapidly entered the soil whole-bodied and were sealed anoxically, although they suffered frombiological and chemical degradation (i.e. pyrite formation/oxidation, mineral dissolution and staining) related to changes in the site's hydrology. Additionally, carbon and nitrogen stable isotopeswere analysed to obtain information on the animals' feeding behaviour. The results show narrowly distributed δ13C ratios, indicating a terrestrial C3 plant-based diet, combined with a wide range in δ15N ratios. This is most likely related to the tortoises' drought-adaptive ability to change their metabolic processes, which can affect the δ15N ratios. Furthermore, ZooMS collagen fingerprinting analysis successfully identified two tortoise species (C. triserrata and C. inepta) in the bone assemblage,which,when combined with stable isotope data, revealed significantly different δ15N ratios between the two tortoise species. As climatic changes around this period resulted in increased aridity in the Mascarene Islands, this could explain the extremely elevated δ15N ratio in our dataset. The endemic fauna was able to endure the climatic changes 4200 years ago, although human arrival in the 17th century changed the original habitat to such an extent that it resulted in the extinction of several species. Fortunately we are still able to study these extinct tortoises due to the beneficial conditions of their burial environment, resulting in excellent bone preservation.

Uranium-series ages of corals, sea level history, and palaeozoogeography, Canary Islands, Spain: An exploratory study for two Quaternary interglacial periods

[EN]We present the first U-series ages of corals from emergent marine deposits on the Canary Islands. Deposits at +. 20. m are 481 ± 39 ka, possibly correlative to marine isotope stage (or MIS) 11, while those at +. 12 and +. 8. m are 120.5 ± 0.8. ka and 130.2 ± 0.8. ka, respectively, correlative to MIS 5.5. The age, elevations, and uplift rates derived from MIS 5.5 deposits on the Canary Islands allow calculations of hypothetical palaeo-sea levels during the MIS 11 high sea stand. Estimates indicate that the MIS 11 high sea stand likely was at least +. 9. m (relative to present sea level) and could have been as high as +. 24. m.

Theatre History and Historiography Ethics, Evidence and Truth

This collection of essays is the first time a group of theatre historians have come together to consider the challenge of applying ethical thinking to attempts to truthfully represent the past. Topics include the life of the celebrated Restoration actor Thomas Betterton, the little-known records of hitherto forgotten women involved in Victorian theatre, amateur theatricals enjoyed by the British army in colonial India, the loss of a pioneering arts centre for African and Caribbean culture, performance art in Wales and present-day community arts in Northern Ireland. While confronting such difficult issues as the instability of evidence and the unreliability of memory, the contributors offer fresh perspectives and innovative strategies for fulfilling their ethical responsibility to the lived experience of the past.