Department of Evolutionary Ecology: Research Focus
We study evolutionary processes that underlie the responses of natural populations to changes in their biotic and abiotic environment. We thereby focus on natural and sexual selection, and study traits, mechanisms and trade-offs that limit and facilitate the long-term survival of wildlife populations, such as dispersal and sexual conflict, or that are of high societal relevance, such as sex roles. To achieve this, we collect long-term, individual-based life-history and fitness data from populations in the wild and conduct experiments on populations living under semi-natural conditions.
Dispersal and sexual conflict are key elements of ecological and evolutionary processes. Yet, we still do not understand well why in most animals, the propensity of individuals to disperse differs between and within the sexes, and why the members of one sex socially dominate those of the other. Using data from a long-term project (>25 years) on an entire population of spotted hyenas in the Ngorongoro Crater, Tanzania, we showed that male-biased dispersal can be an adaptive response to simple female mate-choice rules that evolved to avoid inbreeding (Höner et al. 2007). We also showed, for the first time in a group-living mammal, that stay-home males and dispersers are not inherently different and have similar reproductive success (Davidian et al. 2016). The choice to stay at home or leave home is the outcome of a process during which all males answer the same question: which group offers the best fitness prospects? We further used our long-term hyena data to test whether the fact that in many species one sex dominates the other is, as widely believed, an inevitable consequence of a disparity in strength and ferocity between males and females (Vullioud et al. 2019). We showed that in hyenas, females dominate males because they can rely on greater social support than males, not because they are stronger or more competitive in any other individual attribute. This suggests that social dominance of one sex over the other – a trait that characterises gender roles – does not need to be a direct consequence of sex or physical strength, but can be shaped by the social environment.
Höner OP, Wachter B, East ML, Streich WJ, Wilhelm K, Burke T, Hofer H (2007) Female mate-choice drives the evolution of male-biased dispersal in a social mammal. Nature 448(7155): 798-801.
Davidian E, Courtiol A, Wachter B, Hofer H, Höner OP (2016) Why do some males choose to breed at home when most other males disperse? Science Advances 2: e1501236.
Vullioud C, Davidian E, Wachter B, Rousset F, Courtiol A, Höner OP (2019) Social support drives female dominance in the spotted hyaena. Nature Ecology & Evolution 3: 71-76.
We examine physiological processes that enable individuals to maintain homeostasis, fight pathogens, orient themselves spatially and temporally, and mobilise energy for their diurnal and seasonal movements. To understand these physiological processes, we investigate animals from the molecular and cellular level, to the entire body or family group. We identify how changing environmental conditions, such as a warming climate, affect wildlife, the point at which their physiological potential reaches a limit and what this means for synchronizing with biotic and abiotic factors. For this we conduct experiments with captive populations and collect physiological data from animals in the wild. We do this via minimally-invasive methods (i.e., breath, blood, and faeces), and by using modern bio-logging techniques that allow observation of body functions without impeding the natural movements of wildlife.
Animals need to consume sufficient energy for their daily needs. Some animals migrate to more suitable areas when resources vanish seasonally. During this time, these animals live on a tight energy budget, which they must adjust to face challenges along their seasonal movements. How animals do this, and on which habitats they rely during migration, is important to know in order to effectively protect these species. We study the physiology and behavioural ecology of migratory bats whose energy budgets are dominated by the high metabolic costs of flight, while also being exposed to a variety of anthropogenic threats during migration (Voigt et al. 2015). We conduct our studies with both wild bats along their migration route and bats that are temporarily held in captivity. In the past, it has been assumed that flying bats do not encounter additional metabolic costs for echolocation. Via experiments on Nathuius’ pipistrelles in a wind tunnel, we found that echolocation is associated with increased metabolic rates at high sound intensities (Currie et al 2020). We therefore hypothesize that migrating Nathusius‘ pipistrelles echolocate at relatively low sound intensities in order to avoid overloading their daily energy budget. During additional wind tunnel experiments and field studies, we determined the speed at which Nathusius‘ pipistrelles should migrate in order to cover the longest distances with minimal energy. We confirmed this optimal flight speed in the field for migrating Nathusius‘ pipistrelles (Troxell et al. 2019), highlighting that migrating bats allocate their energy budgets based on optimality criteria. Via measurements of the natural stable carbon isotope ratios in the breath of bats, we demonstrated that migrating Nathusius’ pipistrelles use a mixed fuel, when generating energy from the oxidation of fatty acids from fat stores and nutrients of the insects they hunt during migration (Voigt et al. 2012). Thus, migrating bats depend on insect-rich habitats along their migration route, which will become increasingly difficult in the future given the current decline of insects.
Currie, S. E., Boonman, A., Troxell, S., Yovel, Y., & Voigt, C. C. (2020). Echolocation at high intensity imposes metabolic costs on flying bats. Nature Ecology & Evolution, 4(9), 1174-1177.
Troxell, S. A., Holderied, M. W., Pētersons, G., & Voigt, C. C. (2019). Nathusius' bats optimize long-distance migration by flying at maximum range speed. Journal of Experimental Biology, 222(4).
Voigt, C. C., Sörgel, K., Šuba, J., Keišs, O., & Pētersons, G. (2012). The insectivorous bat Pipistrellus nathusii uses a mixed-fuel strategy to power autumn migration. Proceedings of the Royal Society B: Biological Sciences, 279(1743), 3772-3778.
Voigt, C. C., Lehnert, L. S., Petersons, G., Adorf, F., & Bach, L. (2015). Wildlife and renewable energy: German politics cross migratory bats. European Journal of Wildlife Research, 61(2), 213-219.
We investigate ecological processes which encompass the interactions of animals with their biotic and abiotic environment. Specifically, we investigate intra- and interspecific interactions, i.e. the relationship of animals with individuals of their own and other species, including competitors, predators, and parasites. We study the ecological functions of animals within their habitats, including their ecological services and disservices from an anthropocentric point of view. Specifically, we focus on i) movement ecology, ii) trophic interactions, and iii) competition and coexistence of wildlife species to improve our understanding on how resilient wildlife populations are towards ecological and human-induced perturbations.
By 2050, 70% of the world's population will live in cities and the expanding urban habitats will lead to increasing light pollution, noise emissions and sealed surfaces. Wildlife will only survive in cities in the long term if they manage to adjust to these novel challenges. However, the processes that allow humans and wildlife to coexist in cities are not fully understood. We are investigating foxes, hedgehogs and bats in the Berlin metropolitan area to identify factors that favour or disfavour wildlife survival in urban habitats. Ultimately, we do this to derive management recommendations on how to facilitate coexistence. Using the example of obligate nocturnal bats, we investigate the negative impact of artificial light at night on bat activity (Lewanzik and Voigt 2017, Voigt et al. 2020) and help developing ecologically sustainable lighting concepts (Voigt et al. 2018) that counteract habitat fragmentation due to light pollution. In red foxes and hedgehogs we identify prerequisites of success (flexible feeding habits; Scholz et al 2020) and determinants of failure (disturbance due to human activity; Igal-Paper) in urban habitats. We consider the presence of wildlife in cities as important because they fulfill an important ecological role and because they are as part of the “green space” a central point of reference to nature for people living in cities. Thus, we receive support from citizen scientists in many of these projects, who join us in researching urban wildlife.
Barthel LMF, Wehner D, Schmidt A, Berger A, Hofer H, Fickel J (2020) Unexpected gene-flow in urban environments: the example of the European hedgehog. Animals 10(12), 2315.
Lewanzik, D., & Voigt, C. C. (2017). Transition from conventional to light‐emitting diode street lighting changes activity of urban bats. Journal of Applied Ecology, 54(1), 264-271.
Voigt, C.C., Azam, C., Dekker, J., Ferguson, J., Fritze, M., Gazaryan, S. Hölker, F., Kones, G., Leader, N., Lewanazik, D., Limpens, H.J.G.A., Mathews, F., Rydell, J., Schofield, H., Spoelstra, K., Zagmajster, M., (2018) Guidelines for consideration of bats in lighting projects. EUROBATS publication series #8.
Voigt, C. C., Scholl, J. M., Bauer, J., Teige, T., Yovel, Y., Kramer-Schadt, S., & Gras, P. (2020). Movement responses of common noctule bats to the illuminated urban landscape. Landscape Ecology, 35(1), 189-201.
We study conservation processes, which we envisage as the causes that drive the decline of populations and species, and as reversing mechanisms that help to improve the adaptability of wildlife, ultimately leading to recovering wildlife populations. Our approach to study conservation processes is holistic by involving relevant stakeholders from the very beginning of studies to generate recommendations that will get accepted by decision-makers and parties at all relevant scales. Specifically, we strive to formulate evidence-based management recommendations that turn human-wildlife conflict into coexistence. We consider knowledge transfer as key for successful implementation of conservation goals.
One of the largest free-ranging cheetah populations occurs on the privately owned land of cattle farmers in Namibia. Here, they are threatened by the farmers because they regularly feed on their cattle calves. In our almost 20 year long study, we discovered that cheetahs maintain a communication network which consists of regularly distributed hotspots at trees or other conspicuous landmarks. These hotspots are often visited by cheetahs from the region to exchange olfactory information. This results in high cheetah activities within the hotspots and thus high predation risks for the cattle calves. Once farmers keep their breeding herds away from the hotspots, their losses were reduced to more than 80% and cheetahs preyed instead on naturally occurring prey. In close collaboration with the farmers we derived with our findings, which were based on high-throughput telemetry, a management plan that mitigated the farmer-cheetah-conflict substantially (Melzheimer et al. 2018, 2020).
Melzheimer, J., Streif, S., Wasiolka, B., Fischer, M., Thalwitzer, S., Heinrich, S. K., Weigold, A., Hofer, H., & Wachter, B. (2018). Queuing, take-overs, and becoming a fat cat: Long-term data reveal two distinct male spatial tactics at different life-history stages in Namibian cheetahs. Ecosphere 9(6): e02308. Doi: 10.1002/ecs2.2308.
Melzheimer, J., Heinrich, S. K., Wasiolka, B., Mueller, R., Thalwitzer, S., Palmegiani, I., Weigold, A., Portas, R., Roeder, R., Krofel, M., Hofer, H., & Wachter, B. (2020). Communication hubs of an asocial cat are the source of a human–carnivore conflict and key to its solution. Proceedings of the National Academy of Sciences, 117(52), 33325-33333.