Browsing by Subject "competition"

This thesis evaluates the effects of entry on incumbent firms' prices and procedures volume in dental care markets using difference-in-differences regression and administrative data on private dental care visits reimbursed by the Social Insurance Institution of Finland. The entry is considered as a competition increasing shock. The entrant's prices were remarkably low at the time of the entry and the firm was able to acquire a large share of volume in common procedures performed at the market. Thus, the entrant offered a real low-cost alternative to the residents of the Capital Region. I focus on examinations and fillings, which are two of the most common procedures. Patients face switching costs when changing their dental care provider. This means that incumbent firms with locked-in customers might be able to accommodate the entry easier, than without the switching costs. The results show that incumbent firms do not lower their prices in response to the entry by economically significant amount. However, the results suggest that incumbent firms perform less fillings after the entry. The effect is driven by summer months. The pattern where the incumbent firms do not change their prices and lose a share of their turnover to the entrant is consistent with the theoretical switching costs literature.

Many pathogens are able to survive and reproduce in the environment outside of host for instance by saprotrophic lifestyle. These kinds of pathogens are called opportunistic as compared to obligatory pathogens that cannot interact or reproduce in the environment outside of host. Opportunistic pathogens are subject to strong selection forces in the environment outside of host for instance while they compete for resources they share with other microbes. Ecological interactions in the environment outside of host can therefore influence on the disease dynamics and evolution of virulence of an opportunistic pathogen. No proper theoretical model that would acknowledge opportunistic reproduction and ecological interactions in the environment out side of host has been developed before. Yet it is essential to develop this kind of theoretical model so that the development and dynamics of opportunistic diseases could be predicted and prevented. In this work, an opportunistic disease model was developed that considers both the opportunistic reproduction and the influence of a superior competitor as compared to pathogenic strain on pathogen growth in the environment outside of host. Differential equations in the model represent the density changes in time in the populations of susceptible and infected host, pathogen and rival strain outside host that is not pathogenic. Evolution of virulence of the new opportunistic pathogen meaning the ability to grow from low density in presence of superior competing strain was modeled in differing circumstances. Opportunistic disease dynamics was modeled in differing circumstances, when non-pathogenic competing strain was either present or absent. Equilibrium equations were solvable to a system, where non-pathogenic competing strain was absent, but to a system where non-pathogenic competing strain was present. Analyses of the model were performed with Math Works MATLAB – program. Reproducing inside host gives an opportunity for new opportunistic pathogen to increase in density under circumstances where competition is moderate enough so that the reproduction in the environment outside host may compensate opportunistic pathogen's weaker ability to compete. Reproduction and competition in the environment outside host produce disease dynamics that differ from more traditional SI-models. Density dependence of the reproduction in the environment outside host stabilizes host-parasite system in the absence of competition in the environment outside host. Instead, in the presence of competition the competitive advantage of the non-pathogen strain destabilizes disease dynamics and prevents extinction of the susceptible host. Reproduction in the environment outside host also enables opportunistic pathogen to remain in the environment in the absence of susceptible hosts and functions thus as a potential mechanism for disease out breaks when circumstances change. However, increasing competition in the environment outside host at the expense of opportunistic pathogen may potentially prevent epidemics. Among other things, the model could be applied to biological control with the intension of removing an opportunistic pathogen naturally by weakening its survival in the environment out side of host in a competiotion situation. This kind of biological control could for example be possible in the case of saprotrophic Flavobacterium columnare –fish pathogen that is found in fish farms.

Cladocerans play a key role in the aquatic ecosystem. They are abundant in lakes and are an essential part in the carbon and energy transfer of the food webs. These species are, however, prone to various environmental changes. Estimates have shown that dissolved organic carbon (DOC) concentrations in northern lakes are likely to increase in the future. This increase of DOC in lakes has multiple impacts ranging from nutrient levels to shading impacts reducing primary productions. Investigating changes in cladocerans along a DOC gradient could help us understand how these species might develop in the future in our changing climate. In this Master’s Thesis, I studied how the cladoceran body length and community structure varied between 9 lakes with dissolved organic carbon (DOC) concentration ranging from 2.4-33.5 mg l-1. For the analyses, these lakes where divided into two groups with a threshold of 12 mg l-1 or into groups of three based on their DOC concentrations. Then, the results were compared with cladoceran length data from an earlier study. Additionally, the changes in phytoplankton abundances and communities as well as the relation between DOC concentration and other environmental variables were analysed. The results showed an increase in the cladoceran body length above the DOC threshold. Moreover, the changes in body length varied between the studied genera. Both Ceriodaphnia sp. and Diaphanosoma sp. body length decreased in groups with higher DOC concentrations while Bosmina sp. were larger at high DOC concentrations. DOC concentration did not have any significant effect on the community structure of zooplankton. The studied lakes varied from their environmental condition making comparisons and general statements challenging. The results indicated that DOC concentration regulates the planktonic communities, but it is solely an imprecise predictor for changes in zooplankton communities. However, cladoceran densities seemed to benefit from increased DOC concentrations as nutrient levels also increased. Changes in cladoceran body lengths were challenging to interpret, because there are multiple factors that can have an impact both alone and combined with others.

Non-native species can have complex effects on the abundance of native species potentially altering the functioning of ecosystems negatively. Invasive species can outcompete local species competing for resources, ultimately causing the extinction of local species. Inter- and intraspecific competition can be especially vigorous for limited resources. Invasive species have been thought to be a leading cause in native species extinction, and their effects on native species can be especially pronounced during reproductive crucial life-history stages, such as nest-building. Based on previous information about invasive species and their effects on ecosystems, and previous studies conducted related to invasive species, I conducted an experiment at the Tvärminne zoological station in Hanko, southern Finland during May and June of 2021. I conducted a laboratory experiment in which the test species used were the invasive fish species round goby, that has increased its range across the Baltic Sea rapidly, and the native fish species sand goby. The purpose was to see, if there was any effect the invasive species has on the nesting success and motivation of the native species. Methods included five different treatments in aquariums. The results did not differ statistically between different treatments, length was close to statistical significance. However, these results do not demonstrate, that the round goby has no effect on the nest building motivation of sand gobies. Some factors of the experimental setup might have been faulty, and future studies with a larger sample are needed to examine the effects of competition on native species’ abundance.