Stefania Casagrande

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Verified

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• PhD
• Project Leader at Max Planck Institute for Biological Intelligence

Rapid reduction of body size in populations responding to global warming suggests the involvement of temperature-dependent physiological adjustments during growth, such as mitochondrial alterations, in the efficiency of producing metabolic energy, a process that is poorly explored, especially in endotherms. Here, we examined the mitochondrial metab...

An organism’s response to its environment is largely determined by changes in the energy supplied by aerobic mitochondrial metabolism via adenosine triphosphate (ATP) production. ATP is especially important under energy-demanding conditions, such as during rapid growth. It is currently poorly understood how environmental factors influence energy me...

Glucocorticoids are known to adjust organismal functions, such as metabolism, in response to environmental conditions. Therefore, these hormones are thought to play a key role in regulating the metabolically demanding aspects of reproduction, especially in variable environments. However, support for the hypothesis that variation in glucocorticoid c...

Rapid reduction of body size in response to global warming suggests the involvement of temperature-dependent adjustments occurring during growth, like alterations in the efficiency in producing metabolic energy. Here, we measured body size of nestling shearwaters Calonectris diomedea developing in nests having different temperature ranges, and exam...

Understanding energy metabolism in free-ranging animals is crucial for ecological studies. In birds, red blood cells (RBCs) offer a minimally invasive method to estimate metabolic rate (MR). In this study with European starlings Sturnus vulgaris, we examined how RBC oxygen consumption relates to oxygen use in key tissues (brain, liver, heart, and p...

Telomeres are chromosome protectors that shorten during eukaryotic cell replication and in stressful conditions. Developing individuals are susceptible to telomere erosion when their growth is fast and resources are limited. This is critical because the rate of telomere attrition in early life is linked to health and life span of adults. The metabo...

Telomeres are chromosome protectors that shorten during cell replication and in stressful conditions. Developing individuals are susceptible to telomere erosion when their growth is fast and resources limited. This is critical because the rate of telomere attrition in early life is linked to health and life span of adults. The metabolic telomere at...

Hormones are highly responsive internal signals that help organisms adjust their phenotype to fluctuations in environmental and internal conditions. Our knowledge of the causes and consequences of variations in circulating hormone concentrations has improved greatly in the past. However, this knowledge comes from population-level studies which gene...

Background In egg-laying animals, mothers can influence the developmental environment and thus the phenotype of their offspring by secreting various substances into the egg yolk. In birds, recent studies have demonstrated that different yolk substances can interactively affect offspring phenotype, but the implications of such effects for offspring...

Metabolic rate is a key ecological variable that quantifies the energy expenditure needed to fuel almost all biological processes in an organism. Metabolic rates are typically measured at the whole-organism level (woMR) with protocols that can elicit stress responses due to handling and confinement, potentially biasing resulting data. Improved, non...

Biologists have long appreciated the critical role energy turnover plays in understanding variation in performance and fitness among individuals. Whole-organism metabolic studies have provided key insights into fundamental ecological and evolutionary processes. However, constraints operating at subcellular levels—such as those operating within the...

Glucocorticoids (GCs) are metabolic hormones that promote catabolic processes, which release stored energy and support high metabolic demands such as during prolonged flights of migrating birds. Dietary antioxidants (e.g. anthocyanins) support metabolism by quenching excess reactive oxygen species produced during aerobic metabolism and also by acti...

Telomeres are DNA structures that protect chromosome ends. However, telomeres shorten during cell replication and at critically low lengths can reduce cell replicative potential, induce cell senescence and decrease fitness. Stress exposure, which elevates glucocorticoid hormone concentrations, can exacerbate telomere attrition. This phenomenon has...

Stress exposure can leave long-term footprints within the organism, like in telomeres (TLs), protective chromosome caps that shorten during cell replica-tion and following exposure to stressors. Short TLs are considered to indicate lower fitness prospects, but why TLs shorten under stressful conditions is not understood. Glucocorticoid hormones (GC...

The trade-off between reproductive investment and survival is central to life-history theory, but the relative importance and the complex interactions among the physiological mechanisms mediating it are still debated. Here we experimentally tested whether baseline glucocorticoid hormones, the redox system or their interaction mediate reproductive i...

Animals go through different life history stages such as reproduction, moult, or migration, of which some are more energy-demanding than others. Baseline concentrations of glucocorticoid hormones increase during moderate, predictable challenges and thus are expected to be higher when seasonal energy demands increase, such as during reproduction. By...

Animals go through different life history stages such as reproduction, moult, or migration, of which some are more energy-demanding than others. Baseline concentrations of glucocorticoid hormones increase during moderate, predictable challenges and thus are expected to be higher when seasonal energy demands increase, such as during reproduction. By...

Nighttime light pollution is quickly becoming a pervasive, global concern. Since the invention and proliferation of light‐emitting diodes (LED), it has become common for consumers to select from a range of color temperatures of light with varying spectra. Yet, the biological impacts of these different spectra on organisms remain unclear. We tested...

Sexual selection favours the expression of traits in one sex that attract members of the opposite sex for mating. The nature of sexually selected traits such as vocalization, colour and ornamentation, their fitness benefits as well as their costs have received ample attention in field and laboratory studies. However, sexually selected traits may no...

1.Long-distance migrants are time-constrained as they need to incorporate many annual cycle stages within a year. Migratory passerines moult in the short interval between breeding and migration. To widen this interval, moult may start while still breeding, but this results in flying with moulting wings when food provisioning. 2.We experimentally si...

Song is a sexually selected trait that is thought to be an honest signal of the health condition of an individual in many bird species. For species that breed opportunistically, the quantity of food may be a determinant of singing activity. However, it is not yet known whether the quality of food plays an important role in this respect. The aim of...

Dataset of the study: Positive effect of dietary lutein and cholesterol on the undirected song activity of an opportunistic breeder

Song is a sexually selected trait that is thought to be an honest signal of the health condition of an individual in many bird species. For species that breed opportunistically, the quantity of food may be a determinant of singing activity. However, it is not yet known whether the quality of food plays an important role in this respect. The aim of...

Song is a sexually selected trait that is thought to be an honest signal of the health condition of an individual in many bird species. For species that breed opportunistically, the quantity of food may be a determinant of singing activity. However, it is not yet known whether the quality of food plays an important role in this respect. The aim of...

Much research on animal communication has addressed how costs or constraints determined by the oxidative status of an individual can assure the honesty of visual signals, such as sexually selected color ornaments. However, acoustic communication has been largely overlooked in this respect. Here, we describe the few available studies that have consi...

Hormones are major physiological signals through which individuals flexibly adjust behavioral phenotypes to fluctuations in external and internal conditions. In vertebrates, glucocorticoid (GC) hormones contribute to such phenotypic flexibility, coordinating changes in metabolism, behavior, and the endocrine stress response. While the mechanisms of...

Finding links between hormonal phenotypes and fitness has proven difficult because of considerable within- and among-individual variation in hormone concentrations. One valuable approach is to quantify within-individual hormonal flexibility along an environmental gradient and to relate the resulting reaction norm to fitness-related traits. In wild...

Life history theory predicts that individuals have to trade-off resources between diverse energy-demanding activities, such as mounting an immune response and performing advertisement behaviour. The availability of immunomodulatory micronutrients can affect this trade-off. Carotenoids can upregulate both the humoral and cell-mediated immune respons...

It is hypothesized that variation in immune function between individuals is due to costs incurred to sustain it. Support for this hypothesis mostly comes from short-term studies on the either costs of innate responses or a combination of innate and antibody responses. Key studies on the fitness and physiological costs of acquired immunity, in which...

Despite the appealing hypothesis that carotenoid-based colouration signals oxidative status, evidence supporting the antioxidant function of these pigments is scarce. Recent studies have shown that lutein, the most common carotenoid used by birds, can enhance the expression of non-visual traits, such as birdsong. Nevertheless, the underlying physio...

There are serious concerns about the environmental and ecological degradation caused by modern agriculture and its impact on animal populations. There is therefore a need to assess the reproductive performance of free-living animals in agricultural landscapes. We undertook a 4-year study on the reproductive biology of Eurasian Kestrel Falco tinnunc...

One hypothesis explaining the honesty of secondary sexual traits regulated by testosterone (T) is that T can impair the balance between pro-oxidant compounds and antioxidant defences, favouring a status of oxidative stress that only good quality individuals can sustain (oxidative handicap hypothesis). In the present study, we evaluated for the firs...

One hypothesis explaining the honesty of secondary sexual traits regulated by testosterone (T) is that T can impair the balance between pro-oxidant compounds and antioxidant defences, favouring a status of oxidative stress that only good quality individuals can sustain (oxidative handicap hypothesis). In the present study, we evaluated for the firs...

Despite extensive research, the potential costs that keep secondary sexual traits honest and evolutionary stable remain somewhat elusive. Many carotenoid-based signals are regulated by testosterone (T), which has been suggested to impose a cost to the signaller by suppression of the immune system or an increase in oxidative stress. Results are, how...

The hypothesis that sexual ornaments are honest signals of quality because their expression is dependent on hormones with immune-depressive effects has received ambiguous support. The hypothesis might be correct for those signals that are carotenoid-dependent because the required carotenoid deposition in the signal, stimulated by testosterone, migh...

Recent studies have demonstrated that carotenoid-based traits are under the control of testosterone (T) by up-regulation of carotenoid carriers (lipoproteins) and/or tissue-specific uptake of carotenoids. T can be converted to dihydrotestosterone (DHT) and estradiol (E2), and variation in conversion rate may partly explain some contradictory findin...

The hypothesis that sexual ornaments are honest signals of quality because their expression is dependent on hormones with immune-depressive effects has received ambiguous support. The hypothesis might be correct for those signals that are carotenoid-dependent because the required carotenoid deposition in the signal, stimulated by testosterone, migh...

The body condition index (i.e., body mass corrected for age or size differences) is commonly used to investigate offspring condition in nestling birds. The body condition index reflects different parameters related to the general nutritional state of nestlings and may predict survival prospects. Since conditions experienced during the growth period...

In the context of sexual selection and parent-offspring communication, carotenoid-based coloration operates as a dynamic condition-dependent signal, as pigments stored in the skin and in the bill can be reallocated to other tissues in accordance with physiological needs. We studied the proximate factors affecting the carotenoid-dependent coloration...

The study examined habitat utilization and prey selection by the kestrel Falco tinnunculus in an area of cultivated farmland in Italy, along with field estimates of small mammal abundance. Kestrel males were radiotagged and ranging behaviour and diet were recorded. Kestrels actively selected grasslands both during flight and perching hunting, and m...

Fail-to-hatch kestrel (Falco tinnunculus) eggs collected at the end of the 1999 and 2005 breeding seasons from nest boxes in and around the city of Rome, Italy, were analyzed by gas chromatography with electron capture detection for their PCB content and for the presence of DDT derivatives and other organochlorines. Among the various PCBs, congener...

Pylons of utility lines are commonly used by breeding birds as structures for supporting their nests. Nesting near power lines, however, exposes adult birds and their offspring to the electric and magnetic fields (EMFs) produced by the current. Therefore, we searched for possible relationships between the magnetic field (MF) magnitude experienced b...

Carotenoids are pigments synthesised by autotrophic organisms. For nestlings of raptorial species, which obtain carotenoids from the consumption of other heterotrophic species, the access to these pigments can be crucial. Carotenoids, indeed, have fundamental health maintenance functions, especially important in developing individuals as nestling k...

Question: Is there a genetic difference between early-breeding kestrels (Falco tinnunculus), which typically lay five or six eggs, and late-breeding kestrels, which, although sympatric, usually lay only four eggs? Field site: Cultivated and set-aside fields of a Mediterranean area of 1200 km2, near Rome, Italy. Methods: We compared the genotypes of...

We studied the nest defence behaviour of common kestrel (Falco tinnunculus) pairs against a mount of either a known predator (the hooded crow, Corvus corone cornix) or a novel predator (the raven, Corvus corax). Both corvids are nest predators, are very similar in shape, but the raven is unknown to kestrels living in the study area. This study aime...

The fitness of an organism can be affected by conditions experienced during early development. In light of the impact that oxidative stress can have on the health and ageing of a bird species, this study evaluated factors accounting for the variation in oxidative stress levels in nestlings of the Eurasian kestrel (Falco tinnunculus) by measuring th...

In the context of sexual selection carotenoid based signals are candidates for indicator traits: they have to be taken up in the diet by animals, they can indicate the ability of the bearer to accumulate a limited resource, and they help in maintaining the health status. We investigated the yellow-orange colouration of the tarsi of the kestrel Falc...

Carotenoids have received much attention from biologists because of their ecological and evolutionary implications in vertebrate biology. We sampled Galápagos land iguanas (Conolophus subcristatus) to investigate the types and levels of blood carotenoids and the possible factors affecting inter-population variation. Blood samples were collected fro...

In this study, we analysed the diet of breeding kestrels (Falco tinnunculus) in a Mediter-ranean area with the aim to evaluate the relative importance of both hunting area and indi-vidual feeding behaviour as factors affecting prey selection. Differently from the populations from middle and northern Europe which primarily feed on voles, the kestrel...

The predatory behaviour of four owl species, tawny owl (Strix aluco), long-eared owl (Asio otus), little owl (Athene noctua) and barn owl (Tyto alba), was compared. The birds were wild individ-uals temporarily in captivity for rehabilitation and were tested be-fore release into an outdoor pen. Between four and ten birds per species were individuall...