| environmental and parental influences on offspring health and growth in great tits (parus major). | sexual selection requires both that there is heritable variation in traits related to fitness, and that either some of this variation is linked to traits of the parents, and/or that there are direct benefits of choosing particular individuals as mates. this suggests that if direct benefits are important offspring performance should be predicted by traits of the rearing adults. but if indirect benefits are more significant offspring performance should be predicted by traits of the adults at the n ... | 2013 | 23936081 |
| genomic dissection of variation in clutch size and egg mass in a wild great tit (parus major) population. | clutch size and egg mass are life history traits that have been extensively studied in wild bird populations, as life history theory predicts a negative trade-off between them, either at the phenotypic or at the genetic level. here, we analyse the genomic architecture of these heritable traits in a wild great tit (parus major) population, using three marker-based approaches - chromosome partitioning, quantitative trait locus (qtl) mapping and a genome-wide association study (gwas). the variance ... | 2013 | 23889544 |
| density effect on great tit (parus major) clutch size intensifies in a polluted environment. | long-term data on a great tit (parus major) population breeding in a metal-polluted zone around a copper-nickel smelter indicate that, against expectations, the clutch size of this species is decreasing even though metal emissions in the area have decreased considerably over the past two decades. here, we document long-term population-level changes in the clutch size of p. major and explore if changes in population density, population numbers of competing species, timing of breeding, breeding ha ... | 2013 | 23881512 |
| quantitative assessment of the importance of phenotypic plasticity in adaptation to climate change in wild bird populations. | predictions about the fate of species or populations under climate change scenarios typically neglect adaptive evolution and phenotypic plasticity, the two major mechanisms by which organisms can adapt to changing local conditions. as a consequence, we have little understanding of the scope for organisms to track changing environments by in situ adaptation. here, we use a detailed individual-specific long-term population study of great tits (parus major) breeding in wytham woods, oxford, uk to p ... | 2013 | 23874152 |
| partitioning of genetic variation across the genome using multimarker methods in a wild bird population. | the underlying basis of genetic variation in quantitative traits, in terms of the number of causal variants and the size of their effects, is largely unknown in natural populations. the expectation is that complex quantitative trait variation is attributable to many, possibly interacting, causal variants, whose effects may depend upon the sex, age and the environment in which they are expressed. a recently developed methodology in animal breeding derives a value of relatedness among individuals ... | 2013 | 23848161 |
| genetic background, and not ontogenetic effects, affects avian seasonal timing of reproduction. | avian seasonal timing is a life-history trait with important fitness consequences and which is currently under directional selection due to climate change. to predict micro-evolution in this trait, it is crucial to properly estimate its heritability. heritabilities are often estimated from pedigreed wild populations. as these are observational data, it leaves the possibility that the resemblance between related individuals is not due to shared genes but to ontogenetic effects; when the environme ... | 2013 | 23837446 |
| initial reactivity and magnitude of the acute stress response associated with personality in wild great tits (parus major). | phenotypic correlations, such as those between functionally distinct behavioral traits, can emerge through the action of selection on individual traits, on trait combinations, and through pleiotropic mechanisms. steroid hormones are known to have pleiotropic effects on a suite of behavioral and physiological traits, including stable individual differences in coping with stress. characterizing the stress axis in relation to personality, however, has typically focused on estimating baseline and pe ... | 2013 | 23665102 |
| population growth in a wild bird is buffered against phenological mismatch. | broad-scale environmental changes are altering patterns of natural selection in the wild, but few empirical studies have quantified the demographic cost of sustained directional selection in response to these changes. we tested whether population growth in a wild bird is negatively affected by climate change-induced phenological mismatch, using almost four decades of individual-level life-history data from a great tit population. in this population, warmer springs have generated a mismatch betwe ... | 2013 | 23620055 |
| small increases in corticosterone before the breeding season increase parental investment but not fitness in a wild passerine bird. | correlative evidence from field studies has suggested that baseline concentrations of corticosterone, the main avian glucocorticoid hormone, affect reproductive strategies in vertebrate species. such a role is conceivable in light of corticosterone's function as a metabolic hormone in regulating glucose and fat metabolism. from such correlational studies, however, the question has remained open whether glucocorticoid concentrations change in advance of reproductive activities or whether corticos ... | 2013 | 23523741 |
| more ornamented females produce higher-quality offspring in a socially monogamous bird: an experimental study in the great tit (parus major). | animals are often conspicuously colored and explanations range from aposematism and mimicry to sexual selection. although sexual selection explains vivid coloration in males, functional significance of vivid coloration in females of socially monogamous species remains unclear. the hypothesis of mutual mate choice predicts that more ornamented females produce offspring of higher quality. we tested this prediction in the great tit (parus major), a small, insectivorous, socially monogamous passerin ... | 2013 | 23521836 |
| haplotype structure, adaptive history and associations with exploratory behaviour of the drd4 gene region in four great tit (parus major) populations. | the assessment of genetic architecture and selection history in genes for behavioural traits is fundamental to our understanding of how these traits evolve. the dopamine receptor d4 (drd4) gene is a prime candidate for explaining genetic variation in novelty seeking behaviour, a commonly assayed personality trait in animals. previously, we showed that a single nucleotide polymorphism in exon 3 of this gene is associated with exploratory behaviour in at least one of four western european great ti ... | 2013 | 23506506 |
| impact of pest control strategies on the arthropodofauna living in bird nests built in nestboxes in pear and apple orchards. | pesticide applications have a strong impact on biodiversity in agroecosystems. the present study aimed to assess the impact of pest control strategies on the arthropodofauna of parus major nests built within nestboxes installed in orchards. unlike many studied groups, these arthropod communities are not in direct contact with pesticide sprays (on account of their being sheltered by nestboxes) and are also unable to move away from the treated area. in this pilot study, we estimated the prevalence ... | 2013 | 23448302 |
| brood reduction via intra-clutch variation in testosterone--an experimental test in the great tit. | in birds, yolk androgen concentrations in eggs can increase or decrease over the laying sequence and common hypotheses hold that this serves to favour the competitive ability of either first- or last-hatched chicks depending on the prevailing conditions, and thus promote brood reduction or maintenance of original brood size respectively. intra-clutch variation of testosterone can shift relative competitive ability of siblings and hence competitive dynamics. in a natural population of great tits, ... | 2013 | 23437207 |
| [extrapair paternity in parus major]. | mating systems, as an evolutionary stable strategy, play an important role in animal reproductive process and result from an animal's adaption to their environment, including their inter-specific environment. in the 1980s, extrapair paternity (epp) was first noted in the eurychoric species, the great tit, parus major. as earlier studies indicated, morphology, physiology, behavior, ecological characteristics and mating systems of eurychoric species differ greatly between areas or populations. acc ... | 2013 | 23389978 |
| personality and information gathering in free-ranging great tits. | one aspect of animal personality that has been well described in captivity, but received only little attention in studies in the wild, is that personality types may vary in their behavioural flexibility towards environmental changes. a fundamental factor underlying such differences is believed to be the degree to which individual behavior is guided by environmental stimuli. we tested this hypothesis in the wild using free-ranging great tits. personality variation was quantified using exploratory ... | 2013 | 23383299 |
| avian haemosporidian persistence and co-infection in great tits at the individual level. | many studies have tracked the distribution and persistence of avian haemosporidian communities across space and time at the population level, but few studies have investigated these aspects of infection at the individual level over time. important aspects of parasite infection at the individual level can be missed if only trends at the population level are studied. this study aimed to determine how persistent haemosporida are in great tit individuals recaptured over several years, whether parasi ... | 2013 | 23360530 |
| why longer song elements are easier to detect: threshold level-duration functions in the great tit and comparison with human data. | our study estimates detection thresholds for tones of different durations and frequencies in great tits (parus major) with operant procedures. we employ signals covering the duration and frequency range of communication signals of this species (40-1,010 ms; 2, 4, 6.3 khz), and we measure threshold level-duration (tld) function (relating threshold level to signal duration) in silence as well as under behaviorally relevant environmental noise conditions (urban noise, woodland noise). detection thr ... | 2013 | 23338560 |
| independent sources of condition dependency and multiple pathways determine a composite trait: lessons from carotenoid-based plumage colouration. | many colour ornaments are composite traits consisting of at least four components, which themselves may be more complex, determined by independent evolutionary pathways, and potentially being under different environmental control. to date, little evidence exists that several different components of colour elaboration are condition dependent and no direct evidence exists that different ornamental components are affected by different sources of variation. for example, in carotenoid-based plumage c ... | 2013 | 23331336 |
| predicting demographically sustainable rates of adaptation: can great tit breeding time keep pace with climate change? | populations need to adapt to sustained climate change, which requires micro-evolutionary change in the long term. a key question is how the rate of this micro-evolutionary change compares with the rate of environmental change, given that theoretically there is a 'critical rate of environmental change' beyond which increased maladaptation leads to population extinction. here, we parametrize two closely related models to predict this critical rate using data from a long-term study of great tits (p ... | 2013 | 23209174 |
| pigments versus structure: examining the mechanism of age-dependent change in a carotenoid-based colour. | within-population colour variation is widespread in animals, yet the determinants of variable coloration have been relatively neglected by ecologists. age-dependent expression of conspicuous coloration is prevalent, particularly in birds. such patterns can be generated by multiple combinations of demographic heterogeneity or within-individual change; longitudinal analyses are necessary to establish the importance of these processes. further, although pigment-based colours are composite traits, p ... | 2013 | 23194384 |
| mhc-linked survival and lifetime reproductive success in a wild population of great tits. | major histocompatibility complex (mhc) genes are frequently used as a model for adaptive genetic diversity. although associations between mhc and disease resistance are frequently documented, little is known about the fitness consequences of mhc variation in wild populations. further, most work to date has involved testing associations between mhc genotypes and fitness components. however, the functional diversity of the mhc, and hence the mechanism by which selection on mhc acts, depends on how ... | 2013 | 23190387 |
| individual and population-level impacts of an emerging poxvirus disease in a wild population of great tits. | emerging infectious diseases of wildlife can have severe effects on host populations and constitute a pressing problem for biodiversity conservation. paridae pox is an unusually severe form of avipoxvirus infection that has recently been identified as an emerging infectious disease particularly affecting an abundant songbird, the great tit (parus major), in great britain. in this study, we study the invasion and establishment of paridae pox in a long-term monitored population of wild great tits ... | 2012 | 23185263 |
| emergence of a novel avian pox disease in british tit species. | avian pox is a viral disease with a wide host range. in great britain, avian pox in birds of the paridae family was first diagnosed in a great tit (parus major) from south-east england in 2006. an increasing number of avian pox incidents in paridae have been reported each year since, indicative of an emergent infection. here, we utilise a database of opportunistic reports of garden bird mortality and morbidity to analyse spatial and temporal patterns of suspected avian pox throughout great brita ... | 2012 | 23185231 |
| epidemiology of the emergent disease paridae pox in an intensively studied wild bird population. | paridae pox, a novel avipoxvirus infection, has recently been identified as an emerging infectious disease affecting wild tit species in great britain. the incursion of paridae pox to a long-term study site where populations of wild tits have been monitored in detail for several decades provided a unique opportunity to obtain information on the local-scale epidemiological characteristics of this novel infection during a disease outbreak. using captures of >8000 individual birds, we show that, wi ... | 2012 | 23185230 |
| preparing offspring for a dangerous world: potential costs of being wrong. | adaptive maternal responses to stressful environments before young are born can follow two non-exclusive pathways: either the mother reduces current investment in favor of future investment, or influences offspring growth and development in order to fit offspring phenotype to the stressful environment. inducing such developmental cues, however, may be risky if the environment changes meanwhile, resulting in maladapted offspring. here we test the effects of a predator-induced maternal effect in a ... | 2012 | 23144992 |
| experimental evidence for adaptive personalities in a wild passerine bird. | individuals of the same species differ consistently in risky actions. such 'animal personality' variation is intriguing because behavioural flexibility is often assumed to be the norm. recent theory predicts that between-individual differences in propensity to take risks should evolve if individuals differ in future fitness expectations: individuals with high long-term fitness expectations (i.e. that have much to lose) should behave consistently more cautious than individuals with lower expectat ... | 2012 | 23097506 |
| offspring social network structure predicts fitness in families. | social structures such as families emerge as outcomes of behavioural interactions among individuals, and can evolve over time if families with particular types of social structures tend to leave more individuals in subsequent generations. the social behaviour of interacting individuals is typically analysed as a series of multiple dyadic (pair-wise) interactions, rather than a network of interactions among multiple individuals. however, in species where parents feed dependant young, interactions ... | 2012 | 23097505 |
| nestling erythrocyte resistance to oxidative stress predicts fledging success but not local recruitment in a wild bird. | stressful conditions experienced by individuals during their early development have long-term consequences on various life-history traits such as survival until first reproduction. oxidative stress has been shown to affect various fitness-related traits and to influence key evolutionary trade-offs but whether an individual's ability to resist oxidative stress in early life affects its survival has rarely been tested. in the present study, we used four years of data obtained from a free-living gr ... | 2013 | 23097463 |
| assessing heavy metal pollution using great tits (parus major): feathers and excrements from nestlings and adults. | passerine species have been increasingly used as bioindicators of metal bioaccumulation especially by taking benefit of non-invasive procedures, such as collecting feathers and excrements. in 2009, metal (as, cd, cu, hg, ni, pb, se and zn) concentrations were determined in feathers and excrements of nestling and adult female great tits (parus major) in industrial (a paper mill) and rural sites in maritime pine forests on the west coast of portugal. the aim of this study was to compare the levels ... | 2013 | 23086543 |
| nocturnal loss of body reserves reveals high survival risk for subordinate great tits wintering at extremely low ambient temperatures. | winter acclimatization in birds is a complex of several strategies based on metabolic adjustment accompanied by long-term management of resources such as fattening. however, wintering birds often maintain fat reserves below their physiological capacity, suggesting a cost involved with excessive levels of reserves. we studied body reserves of roosting great tits in relation to their dominance status under two contrasting temperature regimes to see whether individuals are capable of optimizing the ... | 2013 | 23086507 |
| animal cognition: the trade-off to being smart. | great tits that learn to manipulate a device to obtain food in the laboratory go on to lay more eggs in the wild. however, the solver great tits are also more likely to desert their nest. | 2012 | 23058803 |
| environmental and genetic effects on pigment-based vs. structural component of yellow feather colouration. | carotenoid plumage is of widespread use in bird communication. carotenoid-based feather colouration has recently been shown to be dependent on both pigment concentration and feather structure. if these two components are determined differently, one plumage patch may potentially convey different aspects of individual quality. | 2012 | 22590581 |
| ectoparasite reproductive performance when host condition varies. | host condition can influence both the nutritive resources available to parasites and the strength of host defences. since these factors are likely to be correlated, it is unclear whether parasites would be more successful on hosts in good, intermediate or poor conditions. for more complex parasites, like fleas, where larvae depend on adults to extract and make available some essential host resources, host condition can act at two levels. first, it can affect the investment of females into eggs, ... | 2012 | 22614234 |
| inferring social network structure in ecological systems from spatio-temporal data streams. | we propose a methodology for extracting social network structure from spatio-temporal datasets that describe timestamped occurrences of individuals. our approach identifies temporal regions of dense agent activity and links are drawn between individuals based on their co-occurrences across these 'gathering events'. the statistical significance of these connections is then tested against an appropriate null model. such a framework allows us to exploit the wealth of analytical and computational to ... | 2012 | 22696481 |
| egg speckling patterns do not advertise offspring quality or influence male provisioning in great tits. | many passerine birds lay white eggs with reddish brown speckles produced by protoporphyrin pigment. however, the function of these spots is contested. recently, the sexually selected eggshell coloration (ssec) hypothesis proposed that eggshell color is a sexually selected signal through which a female advertises her quality (and hence the potential quality of her future young) to her male partner, thereby encouraging him to contribute more to breeding attempts. we performed a test of the ssec hy ... | 2012 | 22815730 |
| cognitive ability influences reproductive life history variation in the wild. | cognition has been studied intensively for several decades, but the evolutionary processes that shape individual variation in cognitive traits remain elusive [1-3]. for instance, the strength of selection on a cognitive trait has never been estimated in a natural population, and the possibility that positive links with life history variation [1-5] are mitigated by costs [6] or confounded by ecological factors remains unexplored in the wild. we assessed novel problem-solving performance in 468 wi ... | 2012 | 22940473 |
| trace elements in faeces of great tit nestlings in relation to breeding performance in coastal areas in central portugal. | this long-term study (2003-2010) compared the breeding parameters of great tits living in a paper-and-pulp-industry area to those of great tits living in a rural area on the west coast of portugal. we also measured the abundance of caterpillar biomass, an important food source and determinant of breeding success for tits. in 2009, we further analysed trace metal [arsenic (as), calcium (ca), cadmium, copper, mercury (hg), nickel, lead, selenium, and zinc] as well as ca concentrations in excrement ... | 2012 | 22945855 |
| deimatic display in the european swallowtail butterfly as a secondary defence against attacks from great tits. | many animals reduce the risk of being attacked by a predator through crypsis, masquerade or, alternatively, by advertising unprofitability by means of aposematic signalling. behavioural attributes in prey employed after discovery, however, signify the importance of also having an effective secondary defence if a predator uncovers, or is immune to, the prey's primary defence. in butterflies, as in most animals, secondary defence generally consists of escape flights. however, some butterfly specie ... | 2012 | 23056590 |
| activity patterns during food provisioning are affected by artificial light in free living great tits (parus major). | artificial light may have severe ecological consequences but there is limited experimental work to assess these consequences. we carried out an experimental study on a wild population of great tits (parus major) to assess the impact of light pollution on daily activity patterns during the chick provisioning period. pairs that were provided with a small light outside their nest box did not alter the onset, cessation or duration of their working day. there was however a clear effect of artificial ... | 2012 | 22624023 |
| timing in a fluctuating environment: environmental variability and asymmetric fitness curves can lead to adaptively mismatched avian reproduction. | adaptation in dynamic environments depends on the grain, magnitude and predictability of ecological fluctuations experienced within and across generations. phenotypic plasticity is a well-studied mechanism in this regard, yet the potentially complex effects of stochastic environmental variation on optimal mean trait values are often overlooked. using an optimality model inspired by timing of reproduction in great tits, we show that temporal variation affects not only optimal reaction norm slope, ... | 2012 | 22628472 |
| maternal steroids in egg yolk as a pathway to translate predation risk to offspring: experiments with great tits. | exposure of mothers to risk of predation can induce phenotypic changes in offspring as shown in several species. we previously found that cross-fostered great tit (parus major) chicks of females exposed to increased predation risk were smaller and lighter, but had faster wing growth than control cross-fostered chicks, possibly improving predator-escaping abilities. here we examined the possible role of maternal steroids deposited in eggs as an underlying mechanism. we collected eggs from female ... | 2012 | 22326354 |
| quantitative genetics of a carotenoid-based color: heritability and persistent natal environmental effects in the great tit. | the information content of signals such as animal coloration depends on the extent to which variation reflects underlying biological processes. although animal coloration has received considerable attention, little work has addressed the quantitative genetics of color variation in natural populations. we investigated the quantitative genetics of a carotenoid-based color patch, the ventral plumage of mature great tits (parus major), in a wild population. carotenoid-based colors are often suggeste ... | 2012 | 22173462 |
| metal pollution does not bias offspring sex ratio in great tit (parus major). | we measured offspring sex ratios in a resident insectivorous passerine bird, the great tit parus major, to find out whether metal pollution around a finnish copper smelter would bias sex ratios in this territorial forest bird species. besides a direct effect of pollutants, we were interested in possible indirect effects of pollution-related resource limitation, i.e., changes in food quality and quantity, on sex ratio. | 2011 | 22399144 |
| anticipating spring: wild populations of great tits (parus major) differ in expression of key genes for photoperiodic time measurement. | measuring day length is critical for timing annual changes in physiology and behavior in many species. recently, rapid changes in several photoperiodically-controlled genes following exposure to a single long day have been described. components of this 'first day release' model have so far only been tested in highly domesticated species: quail, sheep, goats and rodents. because artificial selection accompanying domestication acts on genes related to photoperiodicity, we must also study this phen ... | 2012 | 22539953 |
| a single long day triggers follicle growth in captive female great tits (parus major) in winter but does not affect laying dates in the wild in spring. | in many forest passerine bird species, rapid climate warming has led to a phenological mismatch between the period of maximum nestlings' food requirements and the period of maximum food availability (seasonal caterpillar biomass peak) due to an insufficient advancement of the birds' laying dates. the initiation of laying is preceded by the development of the gonads, which in birds are regressed outside the breeding season. increasing day length in late winter and early spring triggers a cascade ... | 2012 | 22545123 |
| characterization and 454 pyrosequencing of major histocompatibility complex class i genes in the great tit reveal complexity in a passerine system. | the critical role of major histocompatibility complex (mhc) genes in disease resistance and their highly polymorphic nature make them exceptional candidates for studies investigating genetic effects on survival, mate choice and conservation. species that harbor many mhc loci and high allelic diversity are particularly intriguing as they are potentially under strong selection and studies of such species provide valuable information as to the mechanisms maintaining mhc diversity. however comprehen ... | 2012 | 22587557 |
| a model approach to project the start of egg laying of great tit (parus major l.) in response to climate change. | the aim of this study was to select a phenological model that is able to calculate the beginning of egg laying of great tit (parus major) for both current and future climate conditions. four models (m1-m4) were optimised on long-term phenological observations from the ecological research centre schlüchtern (hessen/germany). model m1 was a common thermal time model that accumulates growing degree days (gdd) on an optimised starting date t (1). since egg laying of great tit is influenced not only ... | 2013 | 22588698 |
| prey community structure affects how predators select for mullerian mimicry. | müllerian mimicry describes the close resemblance between aposematic prey species; it is thought to be beneficial because sharing a warning signal decreases the mortality caused by sampling by inexperienced predators learning to avoid the signal. it has been hypothesized that selection for mimicry is strongest in multi-species prey communities where predators are more prone to misidentify the prey than in simple communities. in this study, wild great tits (parus major) foraged from either simple ... | 2012 | 22237908 |
| increasing temperature, not mean temperature, is a cue for avian timing of reproduction. | timing of reproduction in temperate-zone birds is strongly correlated with spring temperature, with an earlier onset of breeding in warmer years. females adjust their timing of egg laying between years to be synchronized with local food sources and thereby optimize reproductive output. however, climate change currently disrupts the link between predictive environmental cues and spring phenology. to investigate direct effects of temperature on the decision to lay and its genetic basis, we used pa ... | 2012 | 22218320 |
| clutch size and egg volume in great tits (parus major) increase under low intensity electromagnetic fields: a long-term field study. | exposure to electromagnetic fields (emfs) can affect a wide range of biological processes, including reproduction, growth and development. experiments aimed at investigating the biological effects of emfs, focused on potential harmful effects on humans, have been mostly carried out in vitro or with animal models in laboratory conditions. by contrast, studies performed on wild animals are scarce. the effects of emfs created by an electric power line on reproductive traits of a wild great tit (par ... | 2012 | 22863551 |
| effects of temperature on circadian clock and chronotype: an experimental study on a passerine bird. | daily schedules of many organisms, including birds, are thought to affect fitness. timing in birds is based on circadian clocks that have a heritable period length, but fitness consequences for individuals in natural environments depend on the scheduling of entrained clocks. this chronotype, i.e., timing of an individual relative to a zeitgeber, results from interactions between the endogenous circadian clock and environmental factors, including light conditions and ambient temperature. to under ... | 2012 | 22881370 |
| individual variation in avian reproductive physiology does not reliably predict variation in laying date. | most animals reproduce seasonally. they time their reproduction in response to environmental cues, like increasing photoperiod and temperature, which are predictive for the time of high food availability. although individuals of a population use the same cues, they vary in their onset of reproduction, with some animals reproducing consistently early or late. in avian research, timing of reproduction often refers to the laying date of the first egg, which is a key determinant of fitness. experime ... | 2012 | 22884573 |
| acute stress affects the corticosterone level in bird eggs: a case study with great tits (parus major). | in vertebrates, stress experienced by mothers during the early stages of reproduction is an important source of epigenetic modifications in their offspring. birds represent excellent models to test such effects as their maternal investment can be quantified in terms of egg quality. recently, it has been demonstrated that corticosterone (cort) can be transmitted from a female bird into its eggs. however, there is little published evidence about maternal effects that are mediated by acute stress. ... | 2012 | 22906482 |
| intraclutch variation in avian eggshell pigmentation: the anaemia hypothesis. | many passerine species lay eggs that are speckled with dark protoporphyrin pigmentation. because protoporphyrin is mainly derived from the blood, we here formulate and test a new hypothesis that links an increase in anaemia along the laying sequence to within-clutch variation in egg pigmentation. more intense pigmentation is expected if pigments accumulate during enhanced red blood cell production in response to anaemia. reduced pigmentation is expected if pigments are derived from the degradati ... | 2012 | 22434407 |
| manipulation of life-history decisions using leptin in a wild passerine. | seasonal timing of reproduction and the number of clutches produced per season are two key avian life-history traits with major fitness consequences. female condition may play an important role in these decisions. in mammals, body condition and leptin levels are correlated. in birds, the role of leptin remains unclear. we did two experiments where we implanted female great tits with a pellet releasing leptin evenly for 14 days, to manipulate their perceived body condition, or a placebo pellet. i ... | 2012 | 22448288 |
| regression with empirical variable selection: description of a new method and application to ecological datasets. | despite recent papers on problems associated with full-model and stepwise regression, their use is still common throughout ecological and environmental disciplines. alternative approaches, including generating multiple models and comparing them post-hoc using techniques such as akaike's information criterion (aic), are becoming more popular. however, these are problematic when there are numerous independent variables and interpretation is often difficult when competing models contain many differ ... | 2012 | 22479605 |
| the design and cross-population application of a genome-wide snp chip for the great tit parus major. | the vast amount of phenotypic information collected in some wild animal populations makes them extremely valuable for unravelling the genetics of ecologically important traits and understanding how populations adapt to changes in their environment. next generation sequencing has revolutionized the development of large marker panels in species previously lacking genomic resources. in this study, a unique genomics toolkit was developed for the great tit (parus major), a model species in ecology an ... | 2012 | 22487530 |
| worms under cover: relationships between performance in learning tasks and personality in great tits (parus major). | in animals, individual differences in learning ability are common and are in part explained by genetic differences, developmental conditions and by general experience. yet, not all variations in learning are well understood. individual differences in learning may be associated with elementary individual characteristics that are consistent across situations and over time, commonly referred to as personality or temperament. here, we tested whether or not male great tits (parus major) from two sele ... | 2012 | 22532072 |
| long-term familiarity promotes joining in neighbour nest defence. | familiarity plays an important role in the evolution of sociality and cooperation. familiar individuals may gain a reputation for participating in, or defecting from, cooperative tasks. previous research suggests that long-term familiarity with territorial neighbours benefits breeders. we tested the hypothesis that great tits (parus major) are more likely to join in neighbours' nest defence if those neighbours are familiar from the previous year. we show that neighbours that shared a territory b ... | 2012 | 22535641 |
| social environment affects juvenile dispersal in great tits (parus major). | 1. habitat selection can affect individual fitness, and therefore, individuals are expected to assess habitat quality of potential breeding sites before settlement. 2. we investigated the role of social environment on juvenile dispersal behaviour in the great tit (parus major). two main contradictory hypotheses can be formulated regarding social effects on juvenile dispersal as follows: (i) high fledgling density and sex ratio may enhance the intensity of local (kin) competition and, therefore, ... | 2012 | 22309249 |
| parasites as mediators of heterozygosity-fitness correlations in the great tit (parus major). | positive correlations between heterozygosity and fitness traits are frequently observed, and it has been hypothesized, but rarely tested experimentally, that parasites play a key role in mediating the heterozygosity-fitness association. we evaluated this hypothesis in a wild great tit (parus major) population by testing the prediction that the heterozygosity-fitness association would appear in broods experimentally infested with a common ectoparasite, but not in parasite-free broods. we simultan ... | 2012 | 22239550 |
| degradation of rural and urban great tit song: testing transmission efficiency. | acoustic signals play a fundamental role in avian territory defence and mate attraction. several studies have now shown that spectral properties of bird song differ between urban and rural environments. previously this has been attributed to competition for acoustic space as a result of low-frequency noise present in cities. however, the physical structure of urban areas may have a contributory effect. here we investigate the sound degradation properties of woodland and city environments using b ... | 2011 | 22174781 |
| the forms and fitness cost of senescence: age-specific recapture, survival, reproduction, and reproductive value in a wild bird population. | longitudinal studies of senescence accumulate rapidly from natural populations. however, it is largely unknown whether different fitness components senesce in parallel, how reproductive and survival senescence contribute to declines in reproductive value, and how large the fitness cost of senescence is (the difference between the observed reproductive value and the hypothetical reproductive value, if senescence would not occur). we analyzed age-specific survival in great tits parus major and com ... | 2012 | 22173469 |
| nestling development and the timing of tick attachments. | parasites exposed to fast-developing hosts experience a variety of conditions over a short time period. only few studies in vertebrate-ectoparasite systems have integrated the timing of ectoparasite infestations in the host's development into the search for factors explaining ectoparasite burden. in this study we examined the temporal pattern of attachment in a nidicolous tick (ixodes arboricola) throughout the development of a songbird (parus major). in the first experiment, we exposed bird clu ... | 2012 | 22216982 |
| corticosterone responses differ between lines of great tits (parus major) selected for divergent personalities. | animal 'personality' describes consistent individual differences in suites of behaviors, a phenomenon exhibited in diverse animal taxa and shown to be under natural and sexual selection. it has been suggested that variation in personality reflects underlying physiological variation; however there is limited empirical evidence to test this hypothesis in wild animals. the hypothalamic-pituitary-adrenal axis is hypothesized to play a central role in personality variation. here we tested whether in ... | 2012 | 22202603 |
| personality predicts individual responsiveness to the risks of starvation and predation. | theory suggests that individual personality is tightly linked to individual life histories and to environmental variation. the reactive-proactive axis, for example, is thought to reflect whether individuals prioritize productivity or survival, mutually exclusive options that can be caused by conflicts between foraging and anti-predation behaviour. evidence for this trade-off hypothesis, however, is limited. here, we tested experimentally whether exploration behaviour (eb), an assay of proactivit ... | 2012 | 22179807 |
| melatonin delays clutch initiation in a wild songbird. | the hormone melatonin is known to play an important role in regulating many seasonal changes in physiology, morphology and behaviour. in birds, unlike in mammals, melatonin has thus far been thought to play little role in timing seasonal reproductive processes. this view is mainly derived from laboratory experiments on male birds. this study tests whether melatonin is capable of influencing the timing of clutch initiation in wild female songbirds. free-living female great tits (parus major) trea ... | 2012 | 22171024 |
| promiscuity, paternity and personality in the great tit. | understanding causes of variation in promiscuity within populations remain a major challenge. while most studies have focused on quantifying fitness costs and benefits of promiscuous behaviour, an alternative possibility--that variation in promiscuity within populations is maintained because of linkage with other traits-has received little attention. here, we examine whether promiscuity in male and female great tits (parus major)--quantified as extra-pair paternity (epp) within and between nests ... | 2012 | 22130602 |
| exploration behaviour is not associated with chick provisioning in great tits. | in biparental systems, members of the same pair can vary substantially in the amount of parental care they provide to offspring. the extent of this asymmetry should depend on the relative costs and benefits of care. individual variation in personality is likely to influence this trade-off, and hence is a promising candidate to explain differences in care. in addition, plasticity in parental care may also be associated with personality differences. using exploration behaviour (eb) as a measure of ... | 2011 | 22028867 |
| sex-specific effects of the local social environment on juvenile post-fledging dispersal in great tits. | an individual's decision to disperse from the natal habitat can affect its future fitness prospects. especially in species with sex-biased dispersal, we expect the cost-benefit balance for dispersal to vary according to the social environment (e.g., local sex ratio and density). however, little is known about the social factors affecting dispersal decisions and about the temporal and spatial patterns of the dispersal process. in our study, we investigated experimentally the effects of the social ... | 2011 | 21957327 |
| interpopulation variation in contour feather structure is environmentally determined in great tits. | the plumage of birds is important for flying, insulation and social communication. contour feathers cover most of the avian body and among other functions they provide a critical insulation layer against heat loss. feather structure and composition are known to vary among individuals, which in turn determines variation in the insulation properties of the feather. however, the extent and the proximate mechanisms underlying this variation remain unexplored. | 2011 | 21949798 |
| low-frequency songs lose their potency in noisy urban conditions. | many animal species communicate with their mates through acoustic signals, but this communication seems to become a struggle in urbanized areas because of increasing anthropogenic noise levels. several bird species have been reported to increase song frequency by which they reduce the masking impact of spectrally overlapping noise. however, it remains unclear whether such behavioral flexibility provides a sufficient solution to noisy urban conditions or whether there are hidden costs. species ma ... | 2011 | 21876157 |
| within seasons and among years: when are corticosterone levels repeatable? | hormones play a central role in integrating internal and external cues to help mediate life-history decisions as well as changes in behavior and physiology of individuals. describing the consistency of endocrine traits within and among individuals is an important step for understanding whether hormonal traits are dependable predictors of phenotypes that selection could act upon. however, few long-term field studies have investigated the individual consistency of hormonal traits. glucocorticoid h ... | 2011 | 21872600 |
| immune activation reduces sperm quality in the great tit. | mounting an immune response against pathogens incurs costs to organisms by its effects on important life-history traits, such as reproductive investment and survival. as shown recently, immune activation produces large amounts of reactive species and is suggested to induce oxidative stress. sperm are highly susceptible to oxidative stress, which can negatively impact sperm function and ultimately male fertilizing efficiency. here we address the question as to whether mounting an immune response ... | 2011 | 21765955 |
| heterozygosity is unrelated to adult fitness measures in a large, noninbred population of great tits (parus major). | the extent to which heterozygosity-fitness correlations (hfcs) are expected in wild populations is an important and unresolved question in evolutionary biology, because it relates to our understanding of the genetic architecture of fitness. here, we report a study of hfcs in a wild, noninbred population of great tits (parus major), based on a sample comprising 281 individuals typed at 26 markers, resulting in a data set comprising over 5600 genotypes. we regressed pedigree-derived f-score and mu ... | 2011 | 21635602 |
| local sex ratio affects the cost of reproduction. | 1. costs and benefits of reproduction are central to life-history theory, and the outcome of reproductive trade-offs may depend greatly on the ecological conditions in which they are estimated. in this study, we propose that costs and benefits of reproduction are modulated by social effects, and consequently that selection on reproductive rates depends on the social environment. 2. we tested this hypothesis in a great tit parus major population. over 3 years, we altered parental reproductive eff ... | 2012 | 22112192 |
| adaptive timing of detachment in a tick parasitizing hole-nesting birds. | in non-permanent parasites with low intrinsic mobility such as ticks, dispersal is highly dependent on host movements as well as the timing of separation from the hosts. optimal detachment behaviour is all the more crucial in nidicolous ticks as the risk of detaching in non-suitable habitat is high. in this study, we experimentally investigated the detachment behaviour of ixodes arboricola, a nidicolous tick that primarily infests birds roosting in tree-holes. we infested great tits with i. arbo ... | 2012 | 22067275 |
| evidence for the higher importance of signal size over body size in aposematic signaling in insects. | to understand the evolution of warning coloration, it is important to distinguish between different aspects of conspicuous color patterns. as an example, both pattern element size and body size of prey have been shown to enhance the effectiveness of warning signals. however, it is unclear whether the effect of body size is merely a side effect of proportionally increasing pattern elements, or if there is an effect of body size per se. these possibilities were evaluated by offering different size ... | 2011 | 21521142 |
| personality and problem-solving performance explain competitive ability in the wild. | competitive ability is a major determinant of fitness, but why individuals vary so much in their competitiveness remains only partially understood. one increasingly prevalent view is that realized competitive ability varies because it represents alternative strategies that arise because of the costs associated with competitiveness. here we use a population of great tits (parus major) to explore whether individual differences in competitive ability when foraging can be explained by two traits tha ... | 2012 | 21937498 |
| energy expenditure during egg laying is equal for early and late breeding free-living female great tits. | in many bird populations, variation in the timing of reproduction exists but it is not obvious how this variation is maintained as timing has substantial fitness consequences. daily energy expenditure (dee) during the egg laying period increases with decreasing temperatures and thus perhaps only females that can produce eggs at low energetic cost will lay early in the season, at low temperatures. we tested whether late laying females have a higher daily energy expenditure during egg laying than ... | 2012 | 21935666 |
| rearing conditions have long-term consequences for stress responsiveness in free-living great tits. | in captivity, the adrenocortical stress response can be permanently altered by events that occur during early life. free-living animals have rarely been examined in this regard. to examine whether early-life events impact the hypothalamo-pituitary-adrenal (hpa) axis in the natural setting, we evaluated the stress response of free-living interspecifically cross-fostered great tits (parus major). cross-fostered birds may show a long-term potentiation of the adrenocortical stress response because s ... | 2011 | 21925180 |
| twofold cost of reproduction: an increase in parental effort leads to higher malarial parasitaemia and to a decrease in resistance to oxidative stress. | parental effort is usually associated with high metabolism that could lead to an increase in the production of reactive oxidative species giving rise to oxidative stress. since many antioxidants involved in the resistance to oxidative stress can also enhance immune function, an increase in parental effort may diminish the level of antioxidants otherwise involved in parasite resistance. in the present study, we performed brood size manipulation in a population of great tits (parus major) to creat ... | 2012 | 21920974 |
| higher in vitro resistance to oxidative stress in extra-pair offspring. | oxidative stress is considered to act as a universal physiological constraint in life-history evolution of animals. this should be of interest for extra-pair paternity behaviour, and we tested here the prediction that offspring arising from extra-pair matings of female great tits show higher resistance to oxidative stress than within-pair offspring. resistance to oxidative stress, measured as the whole blood resistance to a controlled free-radical attack, was significantly higher for extra-pair ... | 2011 | 21899636 |
| individual benefits of nestling begging: experimental evidence for an immediate effect, but no evidence for a delayed effect. | the evolutionary stability of honest signalling by offspring is thought to require that begging displays be costly, so the costs and benefits of begging--and whether they are experienced individually or by the whole brood--are crucial to understanding the evolution of begging behaviour. begging is known to have immediate individual benefits (parents distribute more food to intensely begging individuals) and delayed brood benefits (parents increase provisioning rate to the brood), but the possibi ... | 2011 | 21123250 |
| songs differing in consistency elicit differential aggressive response in territorial birds. | acoustic signals during intrasexual interactions may help receivers to establish the cost and benefits of engaging in a confrontation versus avoiding the cost of escalation. although birdsong repertoires have been previously suggested as providing information during agonistic encounters, the cost (time/neural resources) of assessing large repertoires may decrease the efficiency of the signal for mutual assessment. acoustic-structural features may, therefore, be used to enable a fast and accurate ... | 2011 | 21123249 |
| testing mechanisms of bergmann's rule: phenotypic decline but no genetic change in body size in three passerine bird populations. | bergmann's rule predicts a decrease in body size with increasing temperature and has much empirical support. surprisingly, we know very little about whether "bergmann size clines" are due to a genetic response or are a consequence of phenotypic plasticity. here, we use data on body size (mass and tarsus length) from three long-term (1979-2008) study populations of great tits (parus major) that experienced a temperature increase to examine mechanisms behind bergmann's rule. we show that adult bod ... | 2011 | 21750384 |
| variation in personality and behavioural plasticity across four populations of the great tit parus major. | 1. interest in the evolutionary origin and maintenance of individual behavioural variation and behavioural plasticity has increased in recent years. 2. consistent individual behavioural differences imply limited behavioural plasticity, but the proximate causes and wider consequences of this potential constraint remain poorly understood. to date, few attempts have been made to explore whether individual variation in behavioural plasticity exists, either within or between populations. 3. we assaye ... | 2012 | 21692798 |
| mimicry between unequally defended prey can be parasitic: evidence for quasi-batesian mimicry. | the nature of signal mimicry between defended prey (known as müllerian mimicry) is controversial. some authors assert that it is always mutualistic and beneficial, whilst others speculate that less well defended prey may be parasitic and degrade the protection of their better defended co-mimics (quasi-batesian mimicry). using great tits (parus major) as predators of artificial prey, we show that mimicry between unequally defended co-mimics is not mutualistic, and can be parasitic and quasi-bates ... | 2010 | 20955507 |
| sometimes slower is better: slow-exploring birds are more sensitive to changes in a vocal discrimination task. | animal personality, defined as consistent individual differences across context and time, has attracted much recent research interest in the study of animal behaviour. more recently, this field has begun to examine how such variation arose and is maintained within populations. the habitat-dependent selection hypothesis, which posits that animals with differing personality types may fare better (i.e. have a fitness advantage) in different habitats, suggests one possible mechanism. in the current ... | 2011 | 20843853 |
| scale and state dependence of the relationship between personality and dispersal in a great tit population. | 1. dispersal is a key process in population biology and ecology. although the general ecological conditions that lead to dispersal have been well studied, the causes of individual variation in dispersal are less well understood. a number of recent studies suggest that heritable temperament - or personality - traits are correlated with dispersal in the wild but the extent to which these 'personality-dispersal syndromes' are general, how they depend on an individual's state and on spatial scale an ... | 2011 | 21488872 |
| effects of social conditions during early development on stress response and personality traits in great tits (parus major). | environmental conditions during early development play a crucial role in shaping an organism's phenotype. to test how social group size affects stress response and behavioral characteristics, we used great tits (parus major) from selection lines for exploratory behavior, a proxy for an avian personality trait, and birds from the wild in a brood size manipulation experiment. nestlings were tested for stress response using an established stress test and after independence subjects were tested for ... | 2011 | 21365640 |
| the use of passerine feathers to evaluate heavy metal pollution in central portugal. | in 2003, two sampling strategies were applied in order to evaluate metal contamination in passerine bird feathers. one strategy included the use of nest boxes and nestling great tits in a forest habitat (mu). the other strategy focused on the use of mist nets to capture adult blackbirds, robins and blackcaps in a fragmented non-forested habitat (est). there was a significantly higher concentration of mercury in great tits (1.09 ± 0.40) sampled in mu and also in robins (3.44 ± 0.91) and blackcaps ... | 2011 | 21312030 |
| the carotenoid conundrum: improved nutrition boosts plasma carotenoid levels but not immune benefits of carotenoid supplementation. | carotenoids are widely heralded as central to honest signaling due to their dual roles as pigments and antioxidants/immunostimulants. the aim of this study is to test if diet quality and carotenoids alone or in an interaction influence condition, carotenoid availability in plasma and immune responsiveness. therefore, a diet experiment during the moult of great tits, parus major, was performed. in a two-way design, we manipulated general quality (digestibility, protein and vitamin content) as wel ... | 2011 | 21301878 |
| difficulties when assessing birdsong learning programmes under field conditions: a re-evaluation of song repertoire flexibility in the great tit. | there is a remarkable diversity of song-learning strategies in songbirds. establishing whether a species is closed- or open-ended is important to be able to interpret functional and evolutionary consequences of variation in repertoire size. most of our knowledge regarding the timing of vocal learning is based on laboratory studies, despite the fact that these may not always replicate the complex ecological and social interactions experienced by birds in the wild. given that field studies cannot ... | 2011 | 21264212 |
| plumage bacterial assemblages in a breeding wild passerine: relationships with ecological factors and body condition. | microorganisms have been shown to play an important role in shaping the life histories of animals, and it has recently been suggested that feather-degrading bacteria influence the trade-off between parental effort and self-preening behavior in birds. we studied a wild breeding population of great tits (parus major) to explore habitat-, seasonal-, and sex-related variation in feather-degrading and free-living bacteria inhabiting the birds' yellow ventral feathers and to investigate associations w ... | 2011 | 21234753 |
| birds and anthropogenic noise: are urban songs adaptive? | in cities with intense low-frequency traffic noise, birds have been observed to sing louder and at a higher pitch. several studies argue that higher song pitch is an adaptation to reduce masking from noise, and it has even been suggested that the song divergence between urban and nonurban songs might lead to reproductive isolation. here we present models of signal transmission to compare the benefits of raised song amplitude and song pitch in terms of sound transmission. we chose two bird specie ... | 2010 | 20712517 |
| antioxidant protection, immune function and growth of nestling great tits parus major in relation to within-brood hierarchy. | differences in competitive abilities of siblings in birds can be caused by a combination of hatching asynchrony and intra-clutch variation in egg quality. however, very little is known how within-brood hierarchies affect the allocation of resources between different functions of the body. we examined the effects of within-brood hierarchy on growth of morphological parameters, blood plasma antioxidant protection and immune function of free-living great tit parus major nestlings. to assure that co ... | 2010 | 20647049 |
| individual variation in rates of senescence: natal origin effects and disposable soma in a wild bird population. | 1. longitudinal studies of various vertebrate populations have recently demonstrated senescent declines in reproductive performance and/or survival probability with age to be almost ubiquitous in nature. little is known, however, about the extent to which rates of senescence vary between individuals, and about causes or consequences of such variation. quantifying these links in natural populations is important for understanding the constraints and adaptive processes underlying the evolution of s ... | 2010 | 20646122 |
| effects of personality on territory defence in communication networks: a playback experiment with radio-tagged great tits. | individuals often differ consistently in behaviour across time and contexts, and such consistent behavioural differences are commonly described as personality. personality can play a central role in social behaviour both in dyadic interactions and in social networks. we investigated whether explorative behaviour, as proxy of personality of territorial male great tits (parus major), predicts their own and their neighbours' territorial responses towards simulated intruders. several weeks prior to ... | 2010 | 20591859 |
| genome-wide snp detection in the great tit parus major using high throughput sequencing. | identifying genes that underlie ecological traits will open exiting possibilities to study gene-environment interactions in shaping phenotypes and in measuring natural selection on genes. evolutionary ecology has been pursuing these objectives for decades, but they come into reach now that next generation sequencing technologies have dramatically lowered the costs to obtain the genomic sequence information that is currently lacking for most ecologically important species. here we describe how we ... | 2010 | 20331773 |