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Introduction
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January 1998 - January 2015
Publications
Publications (80)
Sexual selection and aerodynamic forces affecting structural properties of the flight feathers of birds are poorly understood. Here, we compared the structural features of the innermost primary wing feather (P1) and the sexually dimorphic outermost (Ta6) and monomorphic second outermost (Ta5) tail feathers of barn swallows (Hirundo rustica) from a...
Temporal variation in oxidative physiology and its associated immune function may occur as a result of changes in parasite infection over the year. Evidence from field and laboratory studies suggests links between infection risk, oxidative stress, and the ability of animals to mount an immune response; however the importance of parasites in mediati...
Summary
1. The functional significance of intra- and inter-specific structural variations in the flight feathers of birds is poorly understood. Here, a phylogenetic comparative analysis of four structural features (rachis width, barb and barbule density, and porosity) of proximal and distal primary feathers of 137 European bird species was conducte...
Constitutive innate immunity is the first line of defence against infections, but the causes determining its variability among species are poorly understood. The ‘pace-of-life’ hypothesis predicts that species with fast speed of life, characterized by high energy turnover and short developmental time, invest relatively little in defence in favour o...
Temporally changing environmental conditions occur in most parts of the world and can exert strong pressure on the immune defense of organisms. Seasonality may result in changes in physiological traits over the year, and such changes may be essential for the optimization of defense against infections. Evidence from field and laboratory studies sugg...
Sex-specific physiology is commonly reported in animals, often indicating lower immune indices and higher oxidative stress in males than in females. Sexual selection is argued to explain these differences, but empirical evidence is limited. Here, we explore sex differences in immunity, oxidative physiology and packed cell volume of wild, adult, bre...
Our understanding on how widespread reproductive senescence is in the wild and how the onset and rate of reproductive senescence vary among species in relation to life histories and lifestyles is currently limited. More specifically, whether the species-specific degree of sociality is linked to the occurrence, onset and rate of reproductive senesce...
Social groups often consist of diverse phenotypes, including personality types, and this diversity is known to affect the functioning of the group as a whole. Social selection theory proposes that group composition (i.e. social environment) also influences the performance of individual group members. However, the effect of group behavioural composi...
Our understanding on how widespread reproductive senescence is in the wild and how the onset and rate of reproductive senescence vary among species in relation to life histories and lifestyles is currently limited. More specifically, whether the species-specific degree of sociality is linked to the occurrence, onset and rate of reproductive senesce...
Our understanding on how widespread reproductive senescence is in the wild and how the onset and rate of reproductive senescence vary among species in relation to life histories and lifestyles is currently limited. More specifically, whether the species-specific degree of sociality is linked to the occurrence, onset and rate of reproductive senesce...
Physiological state is an emergent property of the interactions among physiological systems within an intricate network. Understanding the connections within this network is one of the goals in physiological ecology. Here, we studied the relationship between body condition, two neuroendocrine hormones (corticosterone and insulin-like growth factor...
Variation in rachis (central shaft) morphology in individual remiges (flight feathers) within and among species reflects adaptations to requirements imposed by aerodynamic forces, but the fine-scale variation of feather morphology across remiges is not well known. Here we describe how the shape of the rachis, expressed by the height/width ratio, ch...
Down feathers are the first feather types that appear in both the phylogenetic and the ontogenetic history of birds. Although it is widely acknowledged that the primary function of downy elements is insulation, little is known about the interspecific variability in the structural morphology of these feathers, and the environmental factors that have...
Abstract
Social groups often consist of diverse phenotypes, including personality types, and this diversity is known to affect the functioning of the group as a whole. Social selection theory proposes that group composition (i.e. social environment) also influences the performance of individual group members. However, the effect of group behaviour...
Variation in intensity and targets of sexual selection on multiple traits has been suggested to play a major role in promoting phenotypic differentiation between populations , although the divergence in selection may depend on year, local conditions or age. In this study, we quantified sexual selection for two putative sexual signals across two Cen...
The selection pressures that drive flight feather morphology are poorly understood. Using a phylogenetic comparative approach and data from 178 species of birds, we investigated whether both position along the wing length and flight feather length affected vane structure. We found that barb density was lower on distal primaries than on proximal pri...
The selection pressures that drive flight feather morphology are poorly understood. Using a phylogenetic comparative approach and data from 178 species of birds, we investigated whether both position along the wing length and flight feather length affected vane structure. We found that barb density was lower on distal primaries than on proximal pri...
Summary
1. The mechanisms that underpin the evolution of ageing and life histories remain elusive. Oxidative stress, which results in accumulated cellular damages, is one of the mechanisms suggested to play a role.
2. In this paper we set out to test the ‘oxidative stress theory of ageing’ and the ‘oxidative stress hypothesis of life histories’ usi...
Birds often accumulate large fat and protein reserves to fuel long-distance flights. While it is well known that species that fly the longest accumulate the largest amounts of fuel, considerable cross-species variation in fuel load is seen after controlling for overall migration distance. It remains unclear whether this variation can be explained b...
Divergence in acoustic signals plays an important role in the production and maintenance of biodiversity in numerous taxa. In this study, we assess patterns of acoustic divergence in geographically isolated and sympatric subspecies of barn swallows (Hirundo rustica), including analyses of whether song differentiation varies with geographical isolat...
Glucocorticoid (GC) hormones are significant regulators of homeostasis. The physiological effects of GCs critically depend on the time of exposure (short vs. long) as well as on their circulating levels (baseline vs. stress-induced). Previous experiments, in which chronic and high elevation of GC levels was induced, indicate that GCs impair both th...
Organisms face resource trade-offs to support their parental effort and survival. The life-history oxidative stress hypothesis predicts that an individual’s redox state modulates the trade-off between current and residual fitness, but this has seldom been tested experimentally in non-captive organisms. In this study, we manipulated the brood size i...
Studies modelling heat transfer of bird plumage design suggest that insulative properties can be attributed to the density and structure of the downy layer, while waterproofing is the result of the outer layer, comprised of contour feathers. In this study, we test how habitat and thermal condition affect feather mass and density of body feathers (c...
Feather-associated bacteria are widespread inhabitants of avian plumage. However, the determinants of the between-individual variation in plumage bacterial loads are less well understood. Infection intensities can be determined by ecological factors, such as breeding habitat, and can be actively regulated by hosts via preening. Preening, yet, is a...
Fülöp A, Vágási CI, Pap PL 2017. Cohabitation with farm animals rather than breeding effort increases the infection with feather-associated bacteria in the barn swallow Hirundo rustica. Appendices 1 & 2.
1. Body feathers ensure both waterproofing and insulation in waterbirds, but how natural variation in the morphological properties of these appendages relates to environmental constraints remains largely unexplored. Here, we test how habitat and thermal condition affect the morphology of body feathers using a phylogenetic comparative analysis of fi...
Both neutral and adaptive evolutionary processes can cause population divergence, but their relative contributions remain unclear. We investigated the roles of these processes in population divergence in house sparrows (Passer domesticus) from Romania and Bulgaria, regions characterized by high landscape heterogeneity compared to Western Europe. We...
Large brains (relative to body size) might confer fitness benefits to animals. Although the putative costs of well-developed brains can constrain the majority of species to modest brain sizes, these costs are still poorly understood. Given that the neural tissue is energetically expensive and demands antioxidants, one potential cost of developing a...
Sexual selection plays a key role in the diversification of numerous animal clades and may accelerate trait divergence during speciation. However, much of our understanding of this process comes from phylogenetic comparative studies, which rely on surrogate measures such as dimorphism that may not represent selection in wild populations. In this st...
Population divergence in geographic isolation is due to a combination of factors. Natural and sexual selection may be important in shaping patterns of population differentiation, a pattern referred to as 'Isolation by Adaptation' (IBA). IBA can be complementary to the well-known pattern of 'Isolation by Distance' (IBD), in which the divergence of c...
Feathers are dead integumentary structures that are prone to damage and thus show gradual degradation over the course of a year. This loss of quality might have negative fitness consequences. Feather-degrading bacteria (FDB) are one of the most prevalent organisms that degrade feathers, yet the relationship between FDB load and flight feather quali...
Feathers are dead integumentary structures that are prone to damage and thus show gradual degradation over the course of a year. This loss of quality might have negative fitness consequences. Feather-degrading bacteria (FDB) are one of the most prevalent organisms that degrade feathers, yet the relationship between FDB load and flight feather quali...
Migratory flight performance has direct or carry-over effects on fitness. Therefore, selection is expected to act on minimizing the costs of migratory flight, which increases with the distance covered. Aerodynamic theory predicts how morphological adaptations improve flight performance. These predictions have rarely been tested in comparative analy...
The aim of this study was to evaluate the seroprevalence of West Nile and Newcastle Disease viruses in wild and domestic birds from Romania. During 2011–2014, 159 plasma samples from wild birds assigned to 11 orders, 27 families and 61 species and from 21 domestic birds (Gallus gallus domesticus; Anas platyrhynchos) were collected. The sera were as...
Long-distance migratory birds have relatively smaller brains than short-distance migrants or residents. Here, we test whether reduction in brain size with migration distance can be generalized across the different brain regions suggested to play key roles in orientation during migration. Based on 152 bird species, belonging to 61 avian families fro...
Human influences such as climate change, overhunting, land use change, habitat fragmentation and pollution threaten biodiversity. One way for species to respond to ongoing changes is adapting to new conditions. For successful adaptations, species need a high evolutionary adaptive potential, which is maximized by protecting intraspecific genetic var...
Temporal variation in oxidative physiology and its associated immune function may occur as a result of changes in parasite infection over the year. Evidence from field and laboratory studies suggests links between infection risk, oxidative stress, and the ability of animals to mount an immune response; however the importance of parasites in mediati...
Understanding why host species differ so much in symbiont loads and how this depends on ecological host and symbiont traits is a major issue in the ecology of symbiosis. A first step in this inquiry is to know whether observed differences among host species are species-specific traits or more related with host-symbiont environmental conditions. Her...
Innovative behaviors such as exploiting novel food sources can grant significant fitness benefits for animals, yet little is known about the mechanisms driving such phenomena, and the role of physiology is virtually unexplored in wild species. Two hypotheses predict opposing effects of physiological state on innovation success. On one hand, poor ph...
Climate change potentially has important effects on distribution, abundance, transmission and virulence of parasites in wild populations of animals.
Here we analyzed paired information on 89 parasite populations for 24 species of bird hosts some years ago and again in 2010 with an average interval of 10 years. The parasite taxa included protozoa, f...
Defence mechanisms against parasites and pathogens are some of the most elaborate biological systems in animals. The oily secretion of the avian uropygial gland has been suggested to serve as a chemical defence against feather and eggshell bacteria. Yet, the traits associated with uropygial gland oil production are not well understood. We conducted...
Flight initiation distance (FID) is the distance at which an individual animal takes flight when approached by a human. This behavioural measure of risk-taking reflects the risk of being captured by real predators, and it correlates with a range of life history traits, as expected if flight distance optimizes risk of predation. Given that FID provi...
Abstract Female biased sex ratio is a common phenomenon in parasites; however, the cause and consequence of the skewed sex ratio is less well known. Here, we studied the difference in sex ratio, a possible mechanism responsible for the development of unbalanced number of females and its consequences on sexual dimorphism, between 3 louse species par...
Parasites usurp indispensable resources for birds during a moult, and this is particularly relevant for those parasites residing in host intestines. This might compromise the nutritionally demanding moult and, thus, feather functionality. Although lower feather quality has profound and multifaceted adverse effects on residual fitness, surprisingly,...
The preen gland is a holocrine sebaceous gland of the avian integument which produces an oily secretion that is spread on the plumage during preening. It has been suggested that birds may defend themselves against feather-degrading bacteria (FDB) and other potential pathogens using preen gland secretions. However, besides some in vitro studies, the...
The trade-off between current and residual reproductive values is central to life history theory, although the possible mechanisms underlying this trade-off are largely unknown. The 'molt constraint' hypothesis suggests that molt and plumage functionality are compromised by the preceding breeding event, yet this candidate mechanism remains insuffic...
Feather mites are arthropods that live on or in the feathers on birds, and are among the commonest avian ectosymbionts. However, the nature of the ecological interaction between feather mites and birds remains unclear, some studies reporting negative effects of feather mites on their hosts and others reporting positive or no effects. Here we use a...
Sampling sites of house sparrows, geographic grouping, sample size, number of positives, overall prevalence of infection and number of mixed infections of haemosporidian lineages.
(RTF)
Lineage names, parasite genus (H = Haemoproteus, P = Plasmodium), GenBank accession numbers and number of infections per country; Italy (It), France (Fr), Spain (Sp), Bulgaria (Bu), Czech Republic (Cz), Romania (Ro), Russia (Ru), Lithuania (Lit), Norway (No), Sweden (Sw), Egypt (Eg), Israel (Is), Turkey (Tk), Mexico (Mx), USA (USA), Argentina (Ar),...
Invasive species can displace natives, and thus identifying the traits that make aliens successful is crucial for predicting and preventing biodiversity loss. Pathogens may play an important role in the invasive process, facilitating colonization of their hosts in new continents and islands. According to the Novel Weapon Hypothesis, colonizers may...
Feather molt is recognized as an energetically costly activity for birds, and parasite infestation during molt has the potential to reduce host fitness because parasites sequester essential nutrients and stimulate the immune system. We manipulated the coccidian parasite load of captive male House Sparrows (Passer domesticus) by suppressing the natu...
The most important function of moult in birds is the renewal of deteriorated feathers. Worn and holey remiges may incur fitness costs, yet little is known about the factors responsible for the degree of feather wear and sources of variation in feather hole incidence. Here, we report results on variation in feather
quality based on a study of three...
Health status has been hypothesized to be an important factor associated with individual reproductive performance in birds. Sex-specific health status of early- and late-breeding barn swallows (Hirundo rustica) was studied during the prelaying and brood-rearing periods to test the prediction that early-arriving birds are in better health status tha...
The Giurgeu Depression was identified to be an Important Bird Area (IBA), providing breeding and feeding ground for several bird species with European Union and global conservation concerns. In this study we present the list of bird species observed during a 64 years period, between 1946 and 2010. We found 173 species which were observed at least o...
