Auswirkungen des Klimawandels auf eine Reptiliengemeinschaft im ariden Australien
Zusammenfassung der Projektergebnisse
Reptiles in hot deserts are particularly threatened by increasing temperatures and decreasing precipitation through climate change. Therefore, we used a 30-years long-term reptile monitoring scheme of Kinchega National Park, Australia, to investigate the effects of climate change on individuals and populations of eight most abundant lizard species. We found that increasing water availability increased both individuals’ condition and population abundance. Interestingly, water availability could mean increasing local precipitation, but also increasing water level in an adjacent river that occasionally supplies an anabranch through Kinchega National Park. This anabranch remains usually dry but holds water every ten years. The water level in the adjacent river is dependent on the El Niño Southern Oscillation (ENSO), specifically La Niña events, which cause excessive rainfall in Queensland which is then transported to the arid zone across more than 1000 km over almost one year. Thus, a global phenomenon, which does not even affect the desert directly, influences the local lizard diversity. Moreover, both local precipitation and river water levels are complementary, which means that if one parameter was low but the other was high, no negative effects were observed. Surprisingly, increasing temperatures always increased individual conditions and population abundance despite many other studies having hypothesized the opposite. For nocturnal species, the negative effect of cool temperatures can be explained through intensive diurnal thermoregulation behaviour, since individuals actively seek for an optimal warm place to digest leaving less time and less optimal places for gaining energy in comparison to warm temperatures. For diurnal species, effects of vegetation structure were much more important than the absolute hot temperatures. A loss of microhabitats will thus have much more detrimental effects than climate warming itself. However, reactions were also species-specific and we predict that diurnal species already living close to their physiological thermal maximum temperature are more vulnerable to increasing temperatures than other species. Moreover, a combination of extremely hot and dry years decreased individuals’ condition in all species. So far, decreasing body condition, body growth, and delaying sexual maturity buffered effects on the population level, acting as resilience strategy, an ecological phenomenon, which has been widely overlooked when discussing the effects of climate change on biodiversity. Nevertheless, this resilience might not stand a series of extremely hot and dry years, as predicted through climate change, which then could also cascade on to the population level. Another interesting finding was that all species responded equally strong to biotic interactions, such as prey and predator abundance, as to climatic factors. In turn, prey and predatory species were also influenced by climatic factors suggesting a highly complicated network rather than linear relations. Interestingly, to which biotic or abiotic factor a species responded was determined by its traits, such as activity, habitat, body lengths, or longevity. With this study, we could identify key species traits which may serve as indicators for responses of other species and could help to predict species changes under climate change. During this project, some smaller studies were conducted in parallel. In one study, we investigated a new method to estimate the breeding population size, which was also taken up by the media (Müller 2017: Gefährliche Einfalt. Natur 04-17: 40-45).
Projektbezogene Publikationen (Auswahl)
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(2018) Some like it hot: from individual to population responses of an arboreal arid-zone gecko to local and distant climate. Ecol Monogr (Ecological Monographs) 88 (3) 336–352
Grimm-Seyfarth, Annegret; Mihoub, Jean-Baptiste; Gruber, Bernd; Henle, Klaus
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2016. A model-derived short-term estimation method of effective size for small populations with overlapping generations. Methods in Ecology and Evolution 7:734–743
Grimm, A., B. Gruber, M. Hoehn, K. Enders, and K. Henle
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2017. Effects of climate change on a reptile community in arid Australia. Exploring mechanisms and processes in a hot, dry, and mysterious ecosystem. Dissertation. University of Potsdam. 184 S.
Grimm‐Seyfarth, A.
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2017. Too hot to die? The effects of vegetation shading on past, present, and future activity budgets of two diurnal skinks from arid Australia. Ecology and Evolution 7:6803–6813
Grimm‐Seyfarth, A., J. B. Mihoub, and K. Henle
