How does climate change affect biodiversity? - Answering this question is one of

the most important tasks in current ecological research. Earth has been warming by

0.7°C during the last 100 years, and the consequences are already apparent in biotic

systems. For example, species are responding by shifts of their distributional ranges,

which affects the spatial patterns of species richness and turnover. Global temperatures

are projected to rise by 1.8 - 4°C until the end of the century; hence climate change will

most likely leave further imprints on species and ecosystems. This PhD thesis aims to

contribute to a better understanding of the impacts of climate change on species

distributions and spatial patterns of biodiversity.

Contemporary climate change is assumed to be one of the major future threats for

biodiversity, due to its supposedly unprecedented velocity. On the contrary, recent

studies suggest that climatic changes during and after the Pleistocene may have been

much faster than commonly assumed. In one of the studies of this thesis I discuss the

consequences of these findings for species and ecosystems. Since these rapid climate

change events did not cause a broad-spectrum mass extinction, one might assume that

most species may also be able to successfully cope with contemporary climate change.

However, current ecosystems are heavily modified by humans. Among other factors,

habitat destruction and fragmentation caused by anthropogenic land-use changes

negatively affect species' strategies to cope with climate change. Therefore, although

we need to rethink species' abilities to cope with rapid climate change, the interactions

of different threats impose severe challenges for biodiversity. In a global assessment of

future threats for amphibian diversity, I investigate the geography of climate change,

land-use change and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Results

indicated that the regions with highest projected climate and land-use change impacts

show a strong tendency of congruence, but show little overlap with regions of high Bd

prevalence. Overall, two-thirds of the areas harboring the richest amphibian faunas may

be heavily impacted by at least one of the major threats by 2080.

The stability of the climatic niche influences the need for a species to track climate

change via dispersal, or its potential to adapt to novel climatic conditions. I therefore

explore the phylogenetic signal in climatic niches of the world's amphibians, which

serves as a surrogate quantification of niche stability. Results indicate an overall

tendency of phylogenetic signal to be present in realised climatic niches, but signal

strength varies across biogeographical regions and among amphibian orders.

The ability to successfully track climatic changes depends on dispersal, which is in

turn influenced by ecological adaptations, such as the affiliation with a certain habitat

type. A common hypothesis is that species adapted to less persistent habitats have

evolved stronger dispersal abilities. Two studies of my thesis provide evidence for this

hypothesis: (1) geographical distributions of dragonflies adapted to less persistent

habitats show higher degrees of equilibrium with climatic conditions; (2) spatial

patterns of European freshwater species richness and turnover differ strongly among

habitats, indicating a faster post-glacial re-colonization of northern Europe by species

adapted to habitats of lower persistence.