High Arctic Invertebrate Biogeography. Patterns and Colonization Processes since the Last Glacial Maximum

Abstract

The biogeography of Arctic terrestrial invertebrate species, and particularly processes creating and determining patterns of species distribution, have rarely been considered as a whole, but rather on a regional basis, resulting in a lack of an all- encompassing theory of invertebrate colonization of the Arctic. Additionally, dispersal and gene flow to high Arctic islands from populations already inhabiting warmer environments may enhance the survival of Arctic species under the warmer conditions forecasted by climate modellers. Hence there is a need for comprehensive phylogeographical, biodiversity and biogeographical studies to develop a deep understanding of the factors determining species distribution through time and space. Implementing a macroecological approach to this problem by combining community descriptions, field surveys, statistical biogeography and molecular ecology would provide an insight on the historical, geographical and environmental factors that define current invertebrate species distribution in the Arctic. I have tested the following hypothesis: 1) Environmental factors, such as climatic regimes, restrain Arctic invertebrate species distribution at both the landscape and geographical scales.2) Recent glacial history, glacial survival and colonization, have a made a detectible contribution to current distribution of invertebrate species in the Arctic. By addressing these key hypotheses, my research will unravel the history of colonization of the Arctic and develop a critical baseline knowledge from which predictions about potential future changes in biodiversity and geographic distribution of species can be made within the context of climate change. No indications of invertebrate glacial survival in the high Arctic are found on the strength of this thesis However, for none of the scales considered can current environmental conditions provide an adequate explanation of the observed biogeographical patterns. The biogeographical patterns described illustrate the limitations of environmental factors per se in the determination of species distribution ranges and indicate dispersal, including long distance dispersal, as an essential element shaping invertebrate species distribution across all geographical scales.