Intraspecific variation in brain size and architecture : population divergence and phenotypic plasticity

Brain size and architecture exhibit great evolutionary and ontogenetic variation. Yet, studies on population variation (within a single species) in brain size and architecture, or in brain plasticity induced by ecologically relevant biotic factors have been largely overlooked. Here, I address the following questions: (i) do locally adapted populations differ in brain size and architecture, (ii) can the biotic environment induce brain plasticity, and (iii) do locally adapted populations differ in levels of brain plasticity? In the first two chapters I report large variation in both absolute and relative brain size, as well as in the relative sizes of brain parts, among divergent nine-spined stickleback (Pungitius pungitius) populations. Some traits show habitat-dependent divergence, implying natural selection being responsible for the observed patterns. Namely, marine sticklebacks have relatively larger bulbi olfactorii (chemosensory centre) and telencephala (involved in learning) than pond sticklebacks. Further, I demonstrate the importance of common garden studies in drawing firm evolutionary conclusions. In the following three chapters I show how the social environment and perceived predation risk shapes brain development. In common frog (Rana temporaria) tadpoles, I demonstrate that under the highest per capita predation risk, tadpoles develop smaller brains than in less risky situations, while high tadpole density results in enlarged tectum opticum (visual brain centre). Visual contact with conspecifics induces enlarged tecta optica in nine-spined sticklebacks, whereas when only olfactory cues from conspecifics are available, bulbus olfactorius become enlarged.Perceived predation risk results in smaller hypothalami (complex function) in sticklebacks. Further, group-living has a negative effect on relative brain size in the competition-adapted pond sticklebacks, but not in the predation-adapted marine sticklebacks. Perceived predation risk induces enlargement of bulbus olfactorius in pond sticklebacks, but not in marine sticklebacks who have larger bulbi olfactorii than pond fish regardless of predation. In sum, my studies demonstrate how applying a microevolutionary approach can help us to understand the enormous variation observed in the brains of wild animals a point-of-view which I high-light in the closing review chapter of my thesis.

Housing the skilled migrants in the Helsinki Metropolitan Area : International attractiveness of housing, neighbourhoods and the city region

The aim of this thesis is to examine the skilled migrants’ satisfaction with the Helsinki Metropolitan Area. The examination is executed on three scales: housing, neighbourhoods and the city region. Specific focus is on the built environment and how it meets the needs of the migrants. The empirical data is formed of 25 semi-structured interviews with skilled migrants and additionally 5 expert interviews. Skilled and educated workforce is an increasingly important resource in the new economy, and cities are competing globally for talented workers. With aging population and a need to develop its innovational structure, the Helsinki Metropolitan Area needs migrant workforce. It has been stated that quality of place is a central factor for skilled migrants when choosing where to settle, and from this perspective their satisfaction with the region is significant. In housing, the skilled migrants found the price-quality ratio and the general sizes of apartments inadequate. The housing market is difficult for the migrants to approach, since they often do not speak Finnish and there are prejudices towards foreigners. The general quality of housing was rated well. On the neighbourhood level, the skilled migrants had settled in residential areas which are also preferred by the Finnish skilled workers. While the migrants showed suburban orientation in their settlement patterns, they were not concentrated in the suburban areas which host large shares of traditional immigrant groups. Migrants were usually satisfied with their neighbourhoods; however, part of the suburban dwellers were unsatisfied with the services and social life in their neighbourhoods. Considering the level of the city region, the most challenging feature for the skilled migrants was the social life. The migrants felt that the social environment is homogeneous and difficult to approach. The physical environment was generally rated well, the most appreciated features being public transportation, human scale of the Metropolitan Helsinki, cleanliness, and the urban nature. Urban culture and services were seen good for the city region’s size, but lacking in international comparison.

Valikoiva muuttoliike Uudellamaalla

This thesis explores selective migration in Greater Helsinki region from the perspective of counterurbanisation. The aim of the study is to research whether the migration is selective by migrants age, education, income level or the rate of employment and to study any regional patterns formed by the selectivity. In the Helsinki region recent migratory developments have been shifting the areas of net migration gain away from the city of Helsinki to municipalities farther off on the former countryside. There has been discussion about Helsinki s decaying tax revenue base and whether the city s housing policy has contributed to the exodus of wealthier households. The central question of the discussion is one of selective migration: which municipalities succeed in capturing the most favourable migrants and which will lose in the competition. Selective migration means that region s in-migrants and out-migrants significantly differ from each other demographically, socially and economically. Sometimes selectivity is also understood as some individuals greater propensity to migrate than others but the proper notion for this would be differential migration. In Finnish parlance these two concepts have tended to get mixed up. The data of the study covers the total migration of the 34 municipalities of Uusimaa provinces during the years 2001 to 2003. The data was produced by Statistics Finland. Two new methods of representing the selectivity of migration as a whole were constructed during the study. Both methods look at the proportions of favourably selected migrants in regions inward and outward migrant flow. A large share in the inward flow and a small share in the outward flow is good for region s economy and demography. The first method calculates the differences of the proportions of favourably selected four migrant groups and sums the differences up. The other ranks the same proportions between regions giving value 1 to the largest proportion in inward flow and 34 to the smallest, and respectively in outward flow the smallest proportion gets value 1 and the largest 34. The total sum of the ranks or differences in proportions represents region s selectivity of migration. The results show that migration is indeed selective in the Greater Helsinki region. There also seems to be a spatial pattern centred around the Helsinki metropolitan region. The municipalities surrounding the four central communes are generally better of than those farther away. Not only these eight municipalities of the so called capital region benefit from the selective migration, but the favourable structure of migration extends to some of the small municipalities farther away. Some municipalities situated along the main northbound railway line are not coming through as well as other municipalities of the capital region. The selectivity of migration in Greater Helsinki region shows signs of counter-urbanisation. People look for suburban or small-town lifestyle no longer from Espoo or Vantaa, the neighbouring municipalities to Helsinki, but from the municipalities surrounding these two or even farther off. This kind of pattern in selective migration leads to unbalanced development in population structure and tax revenue base in the region. Migration to outskirts of the urban area also leads to urban sprawl and fragmentation of the urban structure: these issues have ecological implications. Selective migration should be studied more. Also the concept itself needs clearer definition and so do the methods to study the selectivity of migration.