School of Doctoral Studies in Biological Sciences, University of South Bohemia, 370 05 České Budějovice, CZECH REPUBLIC.
The thesis extends general knowledge of history and speciation processes in mountain and arctic biota, behavioural thermoregulation and habitat use in butterflies. A common topic of all chapters in my thesis is the importance of environment heterogeneity for speciation and survival of species in the long term (chapter I), differentiation of development length among populations of one species (chapter II), coexistence of several closely related species (chapter III), and finally, for survival of individual species under ongoing changes of landscape structure and climate (chapter III and chapter IV). The conclusions of the studies presented in the thesis are applied in the context of effective conservation of cold-dwelling butterflies in human altered environments.
Chapter I describes biogeography of Holarctic mountain butterflies of the genus Oeneis. The genus originated in mountains of Asia and spread to North America independently in different lineages across Beringian land bridges. The Arctic was colonized also several times by a few independent lineages. Geographic (neutral) speciation was a primary mode of speciation, but also ecological speciation caused divergence of Oeneis species. Ecological speciation was convergent in different developmental lineages. The chapter highlights importance of mountains for conservation of species diversity during climatic changes of the Quaternary period and importance of the Beringia region for survival of arctic biota during cold periods of the Pleistocene. Last, we established that the name Neominois (syn. n.) should be a synonymum of the name Oeneis on the generic level.
In chapter II we described the geographic pattern in biennial abundance fluctuations in adults of a mountain butterfly Erebia euryale in three main mountain ranges of the Czech Republic. We hypothesise that rugged terrain desynchronises the abundance fluctuations within mountain ranges and that the different synchronicity in individual mountain ranges may reflect different postglacial histories of respective populations.
Chapter III describes differences in thermoregulation of seven sympatric species of the genus Erebia, which co-occur in the Alps. These differences were driven by active microhabitat selection of individuals and also by species–specific habitat preferences. We conclude that diverse microhabitat conditions at small spatial scales probably contribute to the sympatric occurrence of closely related species with different thermal demands and that preserving heterogeneous conditions in alpine landscapes might mitigate detrimental consequences of on-going climate change.
Finally, chapter IV illustrates the importance of structurally heterogeneous forest steppe habitats for an aberrant lowland representative of the genus, Erebia aethiops. Males preferred shady habitats of open woodlands, whereas females occurred in more open habitats, i.e. grassland patches within the matrix created by open woodlands. Thus, presence of both habitat types in the close vicinity is necessary to satisfy habitat demands of both sexes.