Species distributions and climate change:current patterns and future scenarios for biodiversity

TY - BOOK

T1 - Species distributions and climate change:current patterns and future scenarios for biodiversity

AU - Hof, Christian

N1 - Supervisor: Carsten Rahbek

PY - 2010/1

Y1 - 2010/1

N2 - How does climate change affect biodiversity? - Answering this question is one ofthe most important tasks in current ecological research. Earth has been warming by0.7°C during the last 100 years, and the consequences are already apparent in bioticsystems. For example, species are responding by shifts of their distributional ranges,which affects the spatial patterns of species richness and turnover. Global temperaturesare projected to rise by 1.8 - 4°C until the end of the century; hence climate change willmost likely leave further imprints on species and ecosystems. This PhD thesis aims tocontribute to a better understanding of the impacts of climate change on speciesdistributions and spatial patterns of biodiversity.Contemporary climate change is assumed to be one of the major future threats forbiodiversity, due to its supposedly unprecedented velocity. On the contrary, recentstudies suggest that climatic changes during and after the Pleistocene may have beenmuch faster than commonly assumed. In one of the studies of this thesis I discuss theconsequences of these findings for species and ecosystems. Since these rapid climatechange events did not cause a broad-spectrum mass extinction, one might assume thatmost 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 changesnegatively affect species' strategies to cope with climate change. Therefore, althoughwe need to rethink species' abilities to cope with rapid climate change, the interactionsof different threats impose severe challenges for biodiversity. In a global assessment offuture threats for amphibian diversity, I investigate the geography of climate change,land-use change and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Resultsindicated that the regions with highest projected climate and land-use change impactsshow a strong tendency of congruence, but show little overlap with regions of high Bdprevalence. Overall, two-thirds of the areas harboring the richest amphibian faunas maybe 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 climatechange via dispersal, or its potential to adapt to novel climatic conditions. I thereforeexplore the phylogenetic signal in climatic niches of the world's amphibians, whichserves as a surrogate quantification of niche stability. Results indicate an overalltendency of phylogenetic signal to be present in realised climatic niches, but signalstrength varies across biogeographical regions and among amphibian orders.The ability to successfully track climatic changes depends on dispersal, which is inturn influenced by ecological adaptations, such as the affiliation with a certain habitattype. A common hypothesis is that species adapted to less persistent habitats haveevolved stronger dispersal abilities. Two studies of my thesis provide evidence for thishypothesis: (1) geographical distributions of dragonflies adapted to less persistenthabitats show higher degrees of equilibrium with climatic conditions; (2) spatialpatterns of European freshwater species richness and turnover differ strongly amonghabitats, indicating a faster post-glacial re-colonization of northern Europe by speciesadapted to habitats of lower persistence.

AB - How does climate change affect biodiversity? - Answering this question is one ofthe most important tasks in current ecological research. Earth has been warming by0.7°C during the last 100 years, and the consequences are already apparent in bioticsystems. For example, species are responding by shifts of their distributional ranges,which affects the spatial patterns of species richness and turnover. Global temperaturesare projected to rise by 1.8 - 4°C until the end of the century; hence climate change willmost likely leave further imprints on species and ecosystems. This PhD thesis aims tocontribute to a better understanding of the impacts of climate change on speciesdistributions and spatial patterns of biodiversity.Contemporary climate change is assumed to be one of the major future threats forbiodiversity, due to its supposedly unprecedented velocity. On the contrary, recentstudies suggest that climatic changes during and after the Pleistocene may have beenmuch faster than commonly assumed. In one of the studies of this thesis I discuss theconsequences of these findings for species and ecosystems. Since these rapid climatechange events did not cause a broad-spectrum mass extinction, one might assume thatmost 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 changesnegatively affect species' strategies to cope with climate change. Therefore, althoughwe need to rethink species' abilities to cope with rapid climate change, the interactionsof different threats impose severe challenges for biodiversity. In a global assessment offuture threats for amphibian diversity, I investigate the geography of climate change,land-use change and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Resultsindicated that the regions with highest projected climate and land-use change impactsshow a strong tendency of congruence, but show little overlap with regions of high Bdprevalence. Overall, two-thirds of the areas harboring the richest amphibian faunas maybe 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 climatechange via dispersal, or its potential to adapt to novel climatic conditions. I thereforeexplore the phylogenetic signal in climatic niches of the world's amphibians, whichserves as a surrogate quantification of niche stability. Results indicate an overalltendency of phylogenetic signal to be present in realised climatic niches, but signalstrength varies across biogeographical regions and among amphibian orders.The ability to successfully track climatic changes depends on dispersal, which is inturn influenced by ecological adaptations, such as the affiliation with a certain habitattype. A common hypothesis is that species adapted to less persistent habitats haveevolved stronger dispersal abilities. Two studies of my thesis provide evidence for thishypothesis: (1) geographical distributions of dragonflies adapted to less persistenthabitats show higher degrees of equilibrium with climatic conditions; (2) spatialpatterns of European freshwater species richness and turnover differ strongly amonghabitats, indicating a faster post-glacial re-colonization of northern Europe by speciesadapted to habitats of lower persistence.

M3 - Ph.D. thesis

BT - Species distributions and climate change:current patterns and future scenarios for biodiversity

PB - Museum Tusculanum

CY - Biologisk Institut

ER -