The physical and behavioral traits of living organisms are molded by their phylogenetic histories and by natural selection. The activity pattern (daily and annual) of an animal is a fundamental behavior that mandates a suite of associated behavioral, physiological and morphological traits.
Activity patterns have evolved in response to the time structure of the numerous features of the environment that change in constant periodicity, and they allow an animal to anticipate these changes and choose the best time for specific behaviors as well as for general activity.
In the research group we study biological rhythms of diverse vertebrate species, asking question regarding the consequences and adaptive significance of biological rhythms, combining diverse and advanced methods, from molecular biology tools in the laboratory to field studies using ecological techniques.
Current projects include:
Most research on circadian rhythms of mammals is being performed on nocturnal laboratory rodents. Therfore, the neural mechanisms responsible for interspecific differences in activity patterns are still poorly understood. Furthermore, it is reasonable to assume that while the circadian systems of nocturnal mammals have been highly conserved, the mechanisms regulating daily rhythms of diurnal species is expected to be more diverse, as this pattern has evolved from the nocturnal ancestral state independently in different lineages. Therefore, studies of the circadian systems of a range of diurnal mammalian species are needed. We try to gain a deeper understanding of the evolution of differences between diurnal and nocturnal mammals, and of the neural mechanisms underlying these differences.
Diurnality, Diabetes and Depression:
Humans are diurnal, mice are not. Nevertheless, most biomedical research, including research related to the circadian
system in humans, is still performed using nocturnal animals. We hypothesize that the switch from the mammalian ancestral nocturnal activity pattern to the current diurnal one demanded a reduction of the robustness of the circadian system which resulted in a higher susceptibility of diurnally active species to diabetes and depression. Studying diurnal rodents, we try to better understand this tendency, to decipher the mechanisms underlying it and eventually develop better ways for coping with it.
Physiological Ecology of Thermoregulation:
In order to survive animals must maintain a balance between energy acquisition (foraging) and energy expenditure.
This challenge is particularly great for endotherm vertebrates that require high amounts of energy to maintain homeothermy. Many endotherms use hibernation, estivation or daily torpor as mechanisms to reduce energy expenditure during anticipated or stochastic periods of stress.
We study the timing and use of daily torpor as a physiological mechanism that affects not only the ability to endure climatic conditions, but also affects inter- and intraspecific ecological interactions and behavioral ecology. The ability to use torpor may influence the outcome of ecological interactions such as predation and competition, and eventually contribute to community structure and species survival.
Hibernation and estivation are the other common pattern of torpor, which may last in total up to a year. Most species use hibernation seasonally, commonly in winter. As a seasonal phenomenon, hibernation probably evolved to allow endotherms to cope with predictable changes in the environment and is timed in response to a predictable environmental cue – day length. Accordingly, at least in some cases, its appearance is controlled by an internal circannual clock, although its duration and timing may also be influenced by resource availability. We study the timing and use of hibernation and estivation in several species including bats, hedgehogs and amphibians.
Global change presents a huge and exciting challenge to the study of thermal physiology. The implication of thermoregulatory strategies and abilities for the survival of individuals and species are of high importance for predicting species response to global change challenges and ways to mitigate them, and for conservation acts.
Humans, a diurnal species, have tried to increase illumination in their immediate environment and create an artificial "eternal summer" for thousands of years. In recent years there has been a growing global concern regarding the possible adverse effects of artificial lights on the ecology and environment of living organisms, including humans. Artificial lighting involves the disruption of one of the most important and predictable cues in the environment, the day/night cycle, and seasonal daylength changes, which allows the development of internal circadian and seasonal programming of behavior and physiology as an adaptive strategy. It also involves the misrepresentation of light as a cue, and affects the foraging abilities of predators and the susceptibility of prey thus affecting population dynamics, habitat use, and also foraging behavior. These effects scale up to the level of ecological communities, but little is understood about this phenomenon. We study the effects of artificial light on the physiological ecology and biological rhythms of organisms.