Genetic variation and inference of demographic histories in non-model species

Both long-term environmental changes such as those driven by the glacial cycles and more recent anthropogenic impacts have had major effects on the past demography in wild organisms. Within species, these changes are reflected in the amount and distribution of neutral genetic variation. In this thesis, mitochondrial and microsatellite DNA was analysed to investigate how environmental and anthropogenic factors have affected genetic diversity and structure in four ecologically different animal species. Paper I describes the post-glacial recolonisation history of the speckled-wood butterfly (Pararge aegeria) in Northern Europe. A decrease in genetic diversity with latitude and a marked population structure were uncovered, consistent with a hypothesis of repeated founder events during the postglacial recolonisation. Moreover, Approximate Bayesian Computation analyses indicate that the univoltine populations in Scandinavia and Finland originate from recolonisations along two routes, one on each side of the Baltic. Paper II aimed to investigate how past sea-level rises affected the population history of the convict surgeonfish (Acanthurus triostegus) in the Indo-Pacific. Assessment of the species’ demographic history suggested a population expansion that occurred approximately at the end of the last glaciation. Moreover, the results demonstrated an overall lack of phylogeographic structure, probably due to the high dispersal rates associated with the species’ pelagic larval stage. Populations at the species’ eastern range margin were significantly differentiated from other populations, which likely is a consequence of their geographic isolation. In Paper III, we assessed the effect of human impact on the genetic variation of European moose (Alces alces) in Sweden. Genetic analyses revealed a spatial structure with two genetic clusters, one in northern and one in southern Sweden, which were separated by a narrow transition zone. Moreover, demographic inference suggested a recent population bottleneck. The inferred timing of this bottleneck coincided with a known reduction in population size in the 19th and early 20th century due to high hunting pressure. In Paper IV, we examined the effect of an indirect but well-described human impact, via environmental toxic chemicals (PCBs), on the genetic variation of Eurasian otters (Lutra lutra) in Sweden. Genetic clustering assignment revealed differentiation between otters in northern and southern Sweden, but also in the Stockholm region. ABC analyses indicated a decrease in effective population size in both northern and southern Sweden. Moreover, comparative analyses of historical and contemporary samples demonstrated a more severe decline in genetic diversity in southern Sweden compared to northern Sweden, in agreement with the levels of PCBs found.

Monosyllabic Circumflexion in Lithuanian

This PhD thesis examines a phenomenon known as Monosyllabic Circumflexion (MC, hereafter) from a historical linguistics / phonological point of view. MC denotes a Lithuanian or Balto-Slavic phenomenon according to which long vowels and diphthongs in monosyllabic words exhibit a circumflex tone instead of the expected acute tone.  It is observed in the following four categories: I. 3rd person future forms of monosyllabic stems (e.g., šõks ― šókti `to jump;' vy͂s ― výti `to drive') II. reflexes of PIE root nouns (e.g., Latv. gùovs `cow;' Lith. šuõ `dog') III. prepositions/adverbs (e.g., nuõ `from' ~  nùotaka `bride;' vė͂l `again' ~ Latv. vêl `still, yet,' tė͂ (permissive particle) < *teh1) IV. pronominal forms (e.g., tuõ ~ gerúoju `the good (m.~sg.~instr.),' tie͂ ~ tíeji `id. (pl.nom)'). The unexpected circumflex tone in these categories is problematic and important for the solution of a Balto-Slavic accentological question on the etymological background of acute and non-acute tones. The aim of this thesis is to partially contribute to the solution of this problem by establishing the existence of MC and its relative chronology. The first category, the 3rd person future forms, provides a substantial number of examples and counterexamples. The examination of them has revealed the fact that the counterexamples constitute a morpho-semantic group of verbs whose future stems underwent considerable morphological changes in the prehistory, hence not exhibiting MC. This shows that the regular tonal reflex of the 3rd person future forms of monosyllabic acute stem must be circumflex, allowing for the establishment of MC as a regular phonological process, although this category does not provide much information on the relative chronology of MC. The second category, the reflexes of Proto-Indo-European root nouns, gives an important clue as to where MC is located in the relative chronology of Balto-Slavic sound changes. Next, there is a discussion of whether the results of the examinations of the first two categories can be maintained for the data of the third and fourth categories, which show an irregular distribution of the acute and circumflex tones in monosyllabic forms. It is shown that various morphological factors, such as homonymic clashes within the paradigms for pronouns, can explain why some monosyllabic forms have acute tone. Also, the linguistic feature of West Aukštaitian dialects of Lithuanian that tend to preserve the results of MC is revealed. These dialects are known to have played an important role in the formation of standard Lithuanian. In this way, the monosyllabic forms with unexpected circumflex tone in Lithuanian are explained as a combination of MC in the Proto-Balto-Slavic time and the dialectal tendency of West Aukštaitian dialects of Lithuanian.