No description available.

No description available.

No description available.

No description available.

No description available.

No description available.

Economic activities are fundamentally influenced by their location in space, which determines the physical and natural environment in which they take place. Likewise, location defines the social context of economic activity prescribing the particular laws, regulations and social norms to which it should conform. Moreover, spatial location defines proximity, which shapes the costs of accessing factor inputs, product markets and other economic and social institutions. In fact, spatial location mediates most forms of interaction, intended and unintended, that may arise from communication and connections between economic agents. These spatial processes have important implications for estimation, policy evaluation and prediction in models of economic activity. This thesis is comprised of two parts. Part I presents a broad range of issues that arise in estimation due to space and frames these as general spatial omitted variables. I explore the use of semi-parametric estimators to identify the parameters of interest in this general model and derive identification conditions for fixed and local adaptive spatial smoothing estimators. The properties of these estimators are contrasted to OLS and spatial econometric estimators. Part II addresses issues in policy evaluation and prediction. I derive an equilibrium sorting model with endogenous tenure choice that can be used to evaluate the general equilibrium welfare effects of policies that affect local environmental quality. Using a series of simulations, motivated by a real world policy application, I contrast the welfare changes derived under this model to a conventional static approach. By allowing for rental and purchase markets the model I develop provides a far richer characterisation of the complex adjustments that propagate through the property market following policy changes and the contrary impact such policies can have upon renters and owners. The usefulness of the model for applied policy analysis is demonstrated through two applications: The Polegate Bypass and Mortgage Interest Deduction reform.

Diatoms are unicellular photosynthetic eukaryotes with a silicate cell wall. They often dominate polar marine ecosystems, driving the major biogeochemical cycles in these areas. The obligate psychrophilic diatom Fragilariopsis cylindrus is a keystone species in the Southern Ocean. It thrives both in open waters and sea ice and has become a model for studying eukaryotic microalgal adaptations to polar marine conditions. The aim of this thesis was to identify how the genome of F. cylindrus has evolved to cope with marine environmental conditions of the Southern Ocean. To identify key genes, comparative genomics, high-throughput transcriptome sequencing and reverse genetics were applied. Comparative genomics with the sequenced mesophilic diatoms Phaeodactylum tricornutum and Thalassiosira pseudonana was combined with genome-wide RNA-Seq transcriptome analysis, leading to the discovery a new bacteria-like rhodopsin not present in other sequenced diatoms. The characterisation of a bacteria-like rhodopsin in F. cylindrus was conducted by applying reverse genetics tools. The genome was characterised by a low G+C content, which affected codon usage. High sequence polymorphism resulted in pronounced unequal expression of putative heterozygous allelic gene copies in response to six different conditions. RNA-Seq detected transcriptional activity for 95% of the 27,137 predicted genes and > 4 fold expression changes between 55% of putative alleles. The most significant transcriptional changes were detected during prolonged darkness affecting 70% of genes and 30% of RNA-Seq reads mapped to unannotated regions of the genome. Two rhodopsin alleles showed unequal bi-allelic expression in response to iron starvation and heterologous expression in Xenopus laevis oocytes experimentally confirmed light-driven proton pumping for the iron-induced rhodopsin allele, suggesting significance for the adaptation of F. cylindrus to environmental conditions of the Southern Ocean. These data show how the polar environment can shape the genome of a eukaryotic phytoplankton in unprecedented detail. High numbers of species-specific genes resulting in expansion of gene and protein families, low G+C likely enabling efficient translation at low temperatures and a high degree of heterozygosity combined with unequal bi-allelic expression, may provide an adaptive strategy to polar conditions by conferring metabolic flexibility and capacity to adapt to a rapidly changing environment.

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The Dynamic Green Ocean Model PlankTOM5.3 is a global ocean biogeochemical model representing interactions between planktonic organisms, ocean and atmosphere. The plankton is divided into five Plankton Functional Types (PFTs), each playing a specific role in carbon and nutrient cycling and in the trophic chain. The growth parameters for each PFT are now being derived in order to represent their dependence on environmental conditions, including climate change. Here we present our work on diatoms, a phytoplankton group of major importance. We reviewed published data on the temperature dependence of diatom growth rate. By applying a quantile regression we calculate the upper-edge of the maximum growth rate. Exponential and optimal curves both have a higher intercept (0.99 and 0.96 d-1) than Eppley’s (1972) curve (0.59 d-1). However, the rates at high temperature are over-estimated by the exponential function. Both average and maximal diatom community growth rate up to 37°C are better represented by an optimal function. Photosynthesis experiments were carried out with an Oxygraph on four diatom species acclimated to different irradiances. PI curve parameters αChl, θm, Pm and Rd were calculated. Compared to the literature, θm values are low, resulting in high αChl values. Values for αChl and θm differs also between polar and temperate species. Optimisation of the model (Buitenhuis and Geider, 2010) give similar θm and lower αChl values than those we calculated. Finally, we applied the optimal temperature-dependence function and our values of αChl and θm to the model PlankTOM5.3. The sensitivity of the ecosystem to each parameter is studied by changing one parameter at a time, in eight different simulations. Primary production varies from 47.28 to 50.44 Pg C yr-1. Changes of PFTs abundance are highest for mixed-phytoplankton and coccolithophores. Meso-zooplankton, mixed-phytoplankton and diatom abundances are more sensitive to changes in temperature-dependence, while coccolithophores respond more to photosynthesis parameters.