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International audience; Artificial light at night disturbs the daily rhythms of many organisms. To what extent this disturbance depends on the intensity and spectral composition of light remain obscure. Here, we measured daily activity patterns of captive blue tits (Cyanistes caeruleus) exposed to similar intensities of green, red, or white light at night. Birds advanced their onset of activity in the morning under all light colors but more under red and white light than under green light. Offset of activity was slightly delayed in all light colors. The total activity over a 24-h period did not change but birds moved a part of their daily activity into the night. Since the effect of red and white lights are comparable, we tested the influence of light intensity in a follow-up experiment, where we compared the activity of the birds under different intensities of green and white light only. While in the higher range of intensities, the effects of white and green light were comparable; at lower intensities, green light had a less disturbing effect as compared with white light on daily rhythms in blue tits. Our results show that the extent of this disturbance can be mitigated by modulating the spectral characteristics and intensity of outdoor lighting, which is now feasible through the use of LED lighting.

Global warming has substantially changed the environment, but the mechanisms to cope with these changes in animals, including the role of maternal effects, are poorly understood. Maternal effects via hormones deposited in eggs, have important environment-dependent effects on offspring development and fitness: thus females are expected to adjust these hormones to the environment, such as the ambient temperature. Longer-term temperature variation could function as a cue, predicting chick rearing conditions to which yolk hormone levels are adjusted, while short-term temperature variation during egg formation may causally affect hormone transfer to eggs. We studied the effects of ambient temperature on yolk androgens (testosterone and androstenedione) and thyroid hormones (thyroxine and triiodothyronine) in great tits (Parus major) using data from unmanipulated clutches from a wild population and from aviary birds (ad libitum food) exposed to different experimental temperature treatments during five years. Both in the wild and in captivity, longer-term pre-laying ambient temperature was not associated with clutch mean yolk hormone levels, while the way androstenedione and thyroxine levels varied across the laying sequence did associate with pre-laying temperature in the wild. Yolk testosterone levels were positively correlated with short-term temperature (during yolk formation) changes within clutches in both wild and captivity. We also report, for the first time in a wild bird, that yolk thyroxine levels correlated with a key environmental factor: thyroxine levels were negatively correlated with ambient temperature during egg formation. Thus, yolk hormone levels, especially testosterone, seem to be causally affected by ambient temperature. These short-term effects might reflect physiological changes in females with changes in ambient temperature. The adaptive value of the variation with ambient temperatures pre-laying or during egg formation should be studied with hormone manipulations in different thermal environments. (C) 2016 Published by Elsevier Inc.

Maternal reproductive investment can critically influence offspring phenotype, and thus these maternal effects are expected to be under strong natural selection. Knowledge on the extent of heritable variation in the physiological mechanisms underlying maternal effects is however limited. In birds, resource allocation to eggs is a key mechanism for mothers to affect their offspring and different components of the egg may or may not be independently adjusted. We studied the heritability of egg components and their genetic and phenotypic covariation in great tits (Parus major), using captive-bred full siblings of wild origin. Egg mass, testosterone (T) and androstenedione (A4) hormone concentrations showed moderate heritability, in agreement with earlier findings. Interestingly, yolk triiodothyronine hormone (T3), but not its precursor, thyroxine hormone (T4), concentration was heritable. An immune factor, albumen lysozyme, showed moderate heritability, but yolk immunoglobulins (IgY) did not. The genetic correlation estimates were moderate but statistically nonsignificant; a trend for a positive genetic correlation was found between A4 and egg mass, T and lysozyme and IgY and lysozyme, respectively. Interestingly, phenotypic correlations were found only between A4 and T, and T4 and T3, respectively. Given that these egg components are associated with fitness-related traits in the offspring (and mother), and that we show that some components are heritable, it opens the possibility that natural selection may shape the rate and direction of phenotypic change via egg composition.Heredity advance online publication, 6 July 2016; doi:10.1038/hdy.2016.49.

© 2018 Amo et al., Small birds use cavities for roosting to decrease the thermoregulatory costs during the winter nights. The ability of birds to detect and escape from an approaching predator is impaired during roosting and thus the selection of such cavities should take into account the risk that a predator will find the cavity. Previous evidence suggested that birds in captivity are able to detect predator scent and avoid roosting in nest-boxes containing such predator chemical cues. Here, we tested whether birds also show this avoidance response under natural conditions. We performed three studies in three populations of blue and great tits. We added predator scent, a pungency scent or an odourless control to nest-boxes and compared the use of these nest-boxes for roosting. We found no differences between the scent treatments in the use of nest-boxes. Therefore, chemical cues indicating the potential presence of a predator are not enough for birds to avoid roosting in nest-boxes under natural conditions., L.A. and G.T. were supported by the postdoctoral JAE-CSIC, the postdoctoral MEC and by the Ramon y Cajal program. IRG was supported by the predoctoral FPI program. The study was funded by the MINECO project CGL2014-58890-P to L.A. and G.T.

In migratory bird species, juveniles normally have shorter and more rounded wings than adults. The causes of this age-specific difference in wing morphology, however, are largely unknown. Here, we used longitudinal data collected over 3years from a Pied Flycatcher Ficedula hypoleuca population to assess whether age-related differences in wing morphology are a consequence of ontogenetic changes or of selection favouring birds with longer and more pointed wings. Our study provides evidence of ontogenetic changes in wing length and shape, whereby birds grow longer and more pointed wings as they grow older. Age-dependent variation is likely to be adaptive and may partly explain age differences in spring migration phenology and breeding success.

Under changing climatic conditions, species need to adapt to their new environment. Genetic adaptation is crucial to prevent population extinction(1) but examples where climate change leads to genetic changes in wild populations have been few(2,3). The synchronization between the timing of egg hatching of a herbivorous insect, the winter moth (Operophtera brumata), and the seasonal bud burst of its food plant, oak (Quercus robur), has been disrupted by climate change(4) and a quantitative genetic model predicts that selection will delay the egg hatching date(5). Here we show, using both long-term observational data and experiments, that the egg hatching date has changed genetically, resulting in closer synchrony with oak bud burst. The observed rate of change matches the predicted rate of change of one day per year. Hence, altered selection pressures, caused by environmental change, result in a rapid adaptive response in insect phenology. These genetic changes in a key life-history trait in this herbivorous insect therefore seem to be fast enough to match the climate-change-induced advancement of their host phenology.

Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous insects such as lepidopteran larvae. Here, we show that great tits (Parus major) discriminate between caterpillar-infested and uninfested trees. Birds were attracted to infested trees, even when they could not see the larvae or their feeding damage. We furthermore show that infested and uninfested trees differ in volatile emissions and visual characteristics. Finally, we show, for the first time, that birds smell which tree is infested with their prey based on differences in volatile profiles emitted by infested and uninfested trees. Volatiles emitted by plants in response to herbivory by lepidopteran larvae thus not only attract predatory insects but also vertebrate predators.

The expression and impact of maternal effects may vary greatly between populations and environments. However, little is known about large-scale geographical patterns of variation in maternal deposition to eggs. In birds, as in other oviparous animals, the outermost maternal component of an egg is the shell, which protects the embryo, provides essential mineral resources and allows its interaction with the environment in the form of gas exchange. In this study, we explored variation of eggshell traits (mass, thickness, pore density and pigmentation) across 15 pied flycatcher populations at a large geographic scale. We found significant between-population variation in all eggshell traits, except in pore density, suggesting spatial variation in their adaptive benefits or in the females' physiological limitations during egg laying. Between- population variation in shell structure was not due to geographic location (latitude and longitude) or habitat type. However, eggshells were thicker in populations that experienced higher ambient temperature during egg laying. This could be a result of maternal resource allocation to the shell being constrained under low temperatures or of an adaptation to reduce egg water loss under high temperatures. We also found that eggshell colour intensity was positively associated with biliverdin pigment concentration, shell thickness and pore density. To conclude, our findings reveal large- scale between-population variation of eggshell traits, although we found little environmental dependency in their expression. Our findings call for further studies that explore other environmental factors (e.g. calcium availability and pollution levels) and social factors like sexual selection intensity that may account for differences in shell structure between populations., This study was financially supported by the former Spanish Ministerio de Innovación y Ciencia (projects CGL2007-61251/BOS and CGL2010-19233-C03-02 to JM, and contract ‘Junta para la Ampliación de Estudios’ to JM, funded by the Spanish Research Council-CSIC and the European Social Fund), Emil AaltonenFoundation in Finland (grant to TL), Finnish Cultural Foundation (grant to SR), Academy of Finland (project 8119367 to TE). EB was financed by a grant for Scientific Schools (NSh-5325.2012.4). Data collection in Moscow region was supported by Russian Fund of Basic Researches (RFBR) and Russian Ministry of Education. RM and VT were supported by the Estonian Ministry of Education and Science (project 0180004s09) and the European Regional Development Fund (Center of Excellence FIBIR).

In birds, the allocation of resources to plumage production may have important fitness consequences. However, we have only a limited understanding of how plumage traits respond to natural selection, making it difficult to predict how variation in plumage traits may contribute to the adaptation of birds to environmental change. In this study, we collected plumage-related data in a pedigreed population of a long-distance migratory bird (the Pied Flycatcher Ficedula hypoleuca) to estimate the heritability of two plumage traits: feather mass (as a proxy of feather quality) and the extent of winter moult. We further explored whether these plumage features were associated with some fitness-related traits. Variation in plumage characteristics could be explained by differences in sex, age and year, which indicates a high degree of plasticity in these traits. After controlling for these effects, however, feather mass and winter moult extent were highly repeatable (r = 0.58–0.82) and heritable (h2 = 0.59–0.65), suggesting that additive genetic variation accounts for a significant proportion of the residual phenotypic variation of plumage traits in this population. Although the studied characteristics showed evolutionary potential, we did not find any relationship between plumage features and fitness-related traits like spring arrival date, egg-laying date, mating success or mating-time. We conclude that current selection on feather mass and moult extent, if existing, is weak, and that these moult-related traits are currently of minor importance for the adaptation of our study population to global warming.

Parental investment and sexually-selected signals can be intimately related, either because the signals indicate the amount of investment that an individual is prepared to make, and hence its value as a mate (the ‘good parent process’), or because individuals are selected to vary their own investment in relation to their mate’s signals (‘differential allocation’ or ‘reproductive compensation’). Correlations between parental investment and the sexually selected signals of both an individual and its mate are therefore of central interest in sexual selection. Blue tits Cyanistes caeruleus are an ideal study species to investigate such correlations because they provide substantial amounts of biparental care and possess sexually-selected structural UV coloration that seems to signal attractiveness in both sexes. We investigated whether feeding rates of male and female blue tits were correlated with either their own or their mate’s UV coloration, and whether any such correlation was affected by the sex ratio of the brood. We also investigated whether any such correlations were reflected in offspring phenotype. Feeding rates were not correlated with either sex of parent’s own UV coloration. However, they were correlated with the mate’s UV coloration, but in opposite directions in males and females: females had higher feeding rates when mated to bright UV males, implying differential allocation, while males had lower feeding rates when mated to bright UV females, implying reproductive compensation. These relationships were unaffected by the sex ratio of the brood. In addition, fledgling tarsus length, but not mass, was related to male UV coloration, and to female UV coloration in interaction with male age. These results suggest that both male and female attractiveness influence parental investment of the mate, and that this in turn affects offspring phenotype. We found no evidence for differential sex allocation.

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 great tits Parus major variation in personality traits is related to plasma concentrations of corticosterone (CORT). Using a capture-restraint protocol we examined baseline and stress-induced CORT levels in two captive experimental groups: (1) birds selected for divergent personalities (‘fast-bold’ and ‘slow-shy’ explorers); and (2) non-selected offspring of wild parents. We first tested for differences in CORT between selection lines, and second examined the relationship between responses in a canonical personality test and CORT concentrations in non-selected birds. We found support for our prediction that the slow-shy line would exhibit a higher acute stress response than the fast-bold line, indicating a genetic correlation between exploratory behavior and stress physiology. We did not, however, find that continuous variation in exploratory behavior co-varies with CORT concentrations in non-selected birds. While our results provide support for the idea that personality emerges as a result of correlated selection on behavior and underlying physiological mechanisms, they also indicate that this link may be particularly evident when composite personality traits are the target of selection.

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 early laying females in 43 great tits (Parus major), by comparing on the same day the DEE of early females late in their laying sequence with DEE of late females early in their egg laying sequence. We also validated the assumption that there are no within female differences in DEE within the egg laying sequence. We found a negative effect of temperature and a positive effect of female body mass on DEE but no evidence for differences in DEE between early and late laying females. However, costs incurred during egg laying may have carry-over effects later in the breeding cycle and if such carry-over effects differ for early and late laying females this could contribute to the maintenance of phenotypic variation in laying dates.

Individuals within species differ in their behavioural reactions to the environment. Consistent individual differences in these behaviours (personality traits) are often correlated and known to be under natural selection. These differences are frequently associated with variation in physiological traits, such as endocrine profiles. For example, variation in circulating testosterone levels is associated with variation in several personality traits and has been hypothesized to be a marker for personality in humans and rodents. The importance of testosterone in controlling both behavioural strategies and individual physiological differences suggests that direct selection on personality traits might cause pleiotropic selection on the physiological mechanisms underlying these traits. To test this hypothesis, we quantified levels of plasma testosterone levels and measured phytohaemagglutinin (PHA)-induced immune responses of male great tits, Parus major, in lines artificially selected for diverging levels of avian personality (‘fast’ and ‘slow’ exploratory behaviour). We found that testosterone levels were highly repeatable within individuals and fluctuated predictably over the season. Contrary to our expectations, ‘slow’ explorers had consistently higher levels of baseline testosterone and higher immune responses than ‘fast’ explorers. These results show that phenotypic selection for variation in personality traits corresponds to consistent differences in hormone profile and immune function, but that higher aggression levels do not need to be associated with higher baseline testosterone levels. Our results confirm that personality traits have evolved as a result of selection on both the underlying controlling physiological mechanisms and the phenotypic traits.

Female birds might be able to manipulate the parental effort of their male partner through elevated transfer of hormones to the eggs, since these hormones affect many chick traits that males might use as cues for adjusting the level of their investment. We experimentally studied whether female pied flycatchers Ficedula hypoleuca could manipulate male investment via yolk androgens. There is much more variation in yolk androgen levels between females than within clutches, and in order to change the androgen levels of the eggs, we swapped whole clutches between nests. To estimate the androgen levels of the clutch, we measured the androgen content of a single egg per clutch. Females did not succeed in manipulating male effort using yolk androgens, since there was no relationship between the division of parental care within a pair and either original or foster egg androgen levels. One of these relationships should have occurred if females were manipulating males. The proportion of feeding visits by the male was higher when the male was old (55%) than when he was young (45%) and females laid eggs with higher androgen levels when mated with a young male. Young males did not exhibit any responses to yolk androgen levels either, which indicates that females cannot exploit their effort more than that of old males. We suggest that females may allocate yolk androgens to adjust the growth trajectories of the chicks to poor growing conditions when mated with young males that are poor providers or occupying a poor territory.

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 body mass decreased over the study period in all populations and that tarsus length increased in one population. Both body mass and tarsus length were heritable and under weak positive directional selection, predicting an increase, rather than a decrease, in body mass. There was no support for microevolutionary change, and thus the observed declines in body mass were likely a result of phenotypic plasticity. Interestingly, this plasticity was not in direct response to temperature changes but seemed to be due to changes in prey dynamics. Our results caution against interpreting recent phenotypic body size declines as adaptive evolutionary responses to temperature changes and highlight the importance of considering alternative environmental factors when testing size clines.

The role of olfaction for predation risk assessment remains barely explored in birds, although predator chemical cues could be useful in predator detection under low visibility conditions for many bird species. We examine whether Great Tits Parus major are able to use the odour of mustelids to assess predation risk when selecting cavities for roosting. We analysed whether the response to predator chemical cues is innate and assessed whether the antipredatory response is associated with exploratory behaviour, a proxy for the personality of birds. In a choice experiment in aviaries, we offered naive adult Great Tits of known personality two nest-boxes, one control and one experimental. The experimental nest-box had the odour of a mustelid predator or a strong new odour without biological significance, the control nest-box contained no odour. When one of the cavities contained the odour of a predator, birds avoided the use of either of the two offered nest-boxes, whereas there was no avoidance of boxes when one of the nest-boxes contained a control odour. There was no relationship with exploratory behaviour. We show that the ability to use the chemical cues of predators is innate in birds, but individual differences in the response to predator chemical cues cannot be explained by the personality of the bird.

Forest type and habitat structure can have profound effects on different aspects of avian life histories. These effects may, however, strongly differ across and within forests that vary in vegetation composition and structure, especially when an ancient forest has been replaced by a new forest. To test for these differences in effect, we studied Great Tit Parus major life-history traits (280 first clutches) in two Mediterranean evergreen forests during 2005–07: an ancient Holm Oak Quercus ilex and a reforested pine forest. A comparison between forests revealed that females breeding in the Holm Oak forest started laying one week later, and produced larger clutches and broods both at hatching and at fledging. Chicks raised in the Holm Oak forest also fledged in better condition. Within forests, however, the reproductive success was not higher for pairs breeding in nestboxes surrounded by oaks within the pine forest, and also reproductive success was not lower in nestboxes surrounded by pines within oak forest. Instead, vegetation maturity around nestboxes, rather than tree species composition, affected hatching success. Surprisingly, hatching success was higher in nestboxes surrounded by immature vegetation. We suggest that this may be due to a lower nest predation rate in nestboxes surrounded by immature vegetation, compared to nestboxes surrounded by mature vegetation. We suggest that different factors appear to affect variation in breeding success in Mediterranean Great Tits comparing across forests (e.g. food availability) vs. within a forest (e.g. nest predation).

Global climate change has led to warmer winters in NW Europe, shortening the distance between suitable overwintering areas and the breeding areas of many bird species. Here we show that winter recovery distances have decreased over the past seven decades, for birds ringed during the breeding season in the Netherlands between 1932 and 2004. Of the 24 species included in the analysis, we found in 12 a significant decrease of the distance to the wintering site. Species from dry, open areas shortened their distance the most, species from wet, open areas the least, while woodland species fall in between the other two habitats. The decline in migration distance is likely due to climate change, as migration distances are negatively correlated with the Dutch temperatures in the winter of recovery. With a shorter migration distance, species should be better able to predict the onset of spring at their breeding sites and this could explain the stronger advancement of arrival date found in several short distance species relative to long-distance migrants.

Personality in animal behaviour describes the observation that behavioural differences between individuals are consistent over time and context. Studies of group-living animals show that movement order among individuals is also consistent over time and context, suggesting that some individuals lead and others follow. However, the relationship between leadership and personality traits is poorly studied. We measured several personality traits and leadership of individual barnacle geese, Branta leucopsis. We measured body size and scored the dominance of individuals living in a stable group situation before subjecting them to an open-field test, an activity test, a novel-object test, and a leadership test in which the order of the movement of individuals in pairs towards a feeding patch was scored. We found high repeatability for activity and novel-object scores over time. Leadership was strongly correlated with novel-object score but not with dominance rank, activity or exploration in an open field. These results provide evidence that leadership is closely related to some aspects of personality. Interestingly, an individual’s arrival at the food patch was affected not only by the novel-object score of the focal individual, but also by the novel-object score of the companion individual, indicating that movement patterns of individuals living in groups are affected by the personality traits of other group members and suggesting that movement patterns of a group may be shaped by the mix of personality types present in the group. Crown Copyright 2009 Published on behalf of The Association for the Study of Animal Behaviour by Elsevier Ltd. All rights reserved.

In resource defence mating systems, males monopolize a resource that is of primary importance for breeding females. For secondary cavity nesters, the availability of suitable nesting sites is important in determining the strength of intrasexual competition, whereby phenotypic and behavioural traits will be favoured that enable individuals to gain access to these sites. The traits that are important in male competition may additionally affect mate choice decisions and a female's investment in the current brood. In a field study on blue tits, Cyanistes caeruleus, we increased intrasexual competition by experimentally limiting nest sites in experimental plots and compared these plots to control plots. Birds breeding in experimental plots did not differ phenotypically from birds in control plots. However, females that bred in the nest site-limited plots fed their offspring at a higher rate than control females. This result indicates that increased competition for limited resources led to more investment in current reproduction, either because successful females were of higher intrinsic quality or because they adjusted their investment in relation to superior territory or male characteristics.

Many bird species reproduce earlier in years with high spring temperatures, but little is known about the causal effect of temperature. Temperature may have a direct effect on timing of reproduction but the correlation may also be indirect, for instance via food phenology. As climate change has led to substantial shifts in timing, it is essential to understand this causal relationship to predict future impacts of climate change. We tested the direct effect of temperature on laying dates in great tits ( Parus major ) using climatized aviaries in a 6-year experiment. We mimicked the temperature patterns from two specific years in which our wild population laid either early (‘warm’ treatment) or late (‘cold’ treatment). Laying dates were affected by temperature directly. As the relevant temperature period started three weeks prior to the mean laying date, with a range of just 4°C between the warm and the cold treatments, and as the birds were fed ad libitum, it is likely that temperature acted as a cue rather than lifting an energetic constraint on the onset of egg production. We furthermore show a high correlation between the laying dates of individuals reproducing both in aviaries and in the wild, validating investigations of reproduction of wild birds in captivity. Our results demonstrate that temperature has a direct effect on timing of breeding, an important step towards assessing the implication of climate change on seasonal timing.

Provisioning visits by helpers are normally assumed to confer positive fitness effects on nestlings, but few studies have actually examined the nutritional value of items helpers fed to offspring. In the cooperatively breeding bell miner, Manorina melanophrys, helpers deliver large proportions of 'lerp', a sugary secretion of psyllids (Hemiptera; Psyllidae). Although lerp is a major food type of adults, its nutritional value is uncertain, especially since nestlings in other nectarivorous species are usually fed only protein-rich arthropods. Helpers in this system are predominantly male and are often unrelated to broods they aid, suggesting helping might be a sexual display, with any nutritional benefits to nestlings being of secondary importance. Detailed observations revealed that the proportion of lerp delivered increased with nestling age, but that it did not differ between helpers and parents, or between related and unrelated helpers. Variation in delivered biomass (lerp+arthropods) had a positive effect on nestling condition, but variation in the proportion of prey constituted by lerp had no measurable effect on nestling mass or condition. Finally, the total amount of food, nestling body mass and condition were all positively related to the number of helpers provisioning broods. These results are consistent with helping in bell miners operating as cooperative investment in brood fitness. Given that lerp was as effective as invertebrate prey in promoting growth, these results also suggest a valid nutritional role for this easily procured food, presumably facilitated by the unusually early development of nestling digestive tracts to utilize these simple sugars. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

1. The aim of the present study is to model the stochastic variation in the size of five populations of great tit Parus major in the Netherlands, using a combination of individual-based demographic data and time series of population fluctuations. We will examine relative contribution of density-dependent effects, and variation in climate and winter food on local dynamics as well as on number of immigrants. 2. Annual changes in population size were strongly affected by temporal variation in number of recruits produced locally as well as by the number of immigrants. The number of individuals recruited from one breeding season to the next was mainly determined by the population size in year t, the beech crop index (BCI) in year t and the temperature during March-April in year t. The number of immigrating females in year t + 1 was also explained by the number of females present in the population in year t, the BCI in autumn year t and the temperature during April-May in year t. 3. By comparing predictions of the population model with the recorded number of females, the simultaneous modelling of local recruitment and immigration explained a large proportion of the annual variation in recorded population growth rates. 4. Environmental stochasticity especially caused by spring temperature and BCI did in general contribute more to annual fluctuations in population size than density-dependent effects. Similar effects of climate on local recruitment and immigration also caused covariation in temporal fluctuations of immigration and local production of recruits. 5. The effects of various variables in explaining fluctuations in population size were not independent, and the combined effect of the variables were generally non-additive. Thus, the effects of variables causing fluctuations in population size should not be considered separately because the total effect will be influenced by covariances among the explanatory variables. 6. Our results show that fluctuations in the environment affect local recruitment as well as annual fluctuations in the number of immigrants. This effect of environment on the interchange of individuals among populations is important for predicting effects of global climate change on the pattern of population fluctuations.

For multiple-brooded species, the number of reproductive events per year is a major determinant of an individual's fitness. Where multiple brooding is facultative, its occurrence is likely to change with environmental conditions, and, as a consequence, the current rates of environmental change could have substantial impacts on breeding patterns. Here we examine temporal population-level trends in the proportion of female great tits ( Parus major ) producing two clutches per year (‘double brooding’) in four long-term study populations in The Netherlands, and show that the proportion of females that double brood has declined in all populations, with the strongest decline taking place in the last 30 years of the study. For one of the populations, for which we have data on caterpillar abundance, we show that the probability that a female produces a second clutch was related to the timing of her first clutch relative to the peak in caterpillar abundance, and that the probability of double brooding declined over the study period. We further show that the number of recruits from the second clutch decreased significantly over the period 1973–2004 in all populations. Our results indicate that adjustment to changing climatic conditions may involve shifts in life-history traits other than simply the timing of breeding.

Interest in personality is growing in a wide range of disciplines, but only in a few systems it is possible to assess the survival value of personality. Field studies looking at the relationship between personality and survival value early in life are greatly hampered by the fact that personality can at present only be assessed after individuals become independent from their parents. In passerines, for example, this is often after a period of intensive selection for the survival on fledglings. The main aim of this study is therefore to develop a method to measure personality before this period of selection. For this purpose, we developed the handling stress (HS) test. We measured HS in 14-d-old great tit nestlings by counting the number of breast movements (breath rate) in four subsequent 15-s bouts for 1 min; before and after they were socially isolated from their siblings for 15 min. To calculate the repeatability of HS, we repeated the test 6 mo later. To assess the relat! ionship between HS and exploratory behaviour, we correlated the outcome of both tests. We ran tests both on birds of lines selected for extreme personality and on wild birds from a natural population. We found that birds selected for fast exploration reacted more to HS compared with birds selected for slow exploration and that HS was repeatable in different life phases. We confirmed this by finding an increase in the HS with increasing exploratory scores in wild birds. These results show that we can use the HS test as a measurement of personality, making it a potential tool for studying the relationship between personality and survival value early in life.

Climate change has been shown to affect the phenology of many organisms, but interestingly these shifts are often unequal across trophic levels, causing a mismatch between the phenology of organisms and their food.We consider two alternative hypotheses: consumers are constrained to adjust sufficiently to the lower trophic level, or prey species react more strongly than their predators to reduce predation. We discuss both hypotheses with our analyses of changes in phenology across four trophic levels: tree budburst, peak biomass of herbivorous caterpillars, breeding phenology of four insectivorous bird species and an avian predator.In our long-term study, we show that between 1988 and 2005, budburst advanced (not significantly) with 0.17 d yr(-1), while between 1985 and 2005 both caterpillars (0.75 d year(-1)) and the hatching date of the passerine species (range for four species: 0.36-0.50 d year(-1)) have advanced, whereas raptor hatching dates showed no trend.The caterpillar peak date was closely correlated with budburst date, as were the passerine hatching dates with the peak caterpillar biomass date. In all these cases, however, the slopes were significantly less than unity, showing that the response of the consumers is weaker than that of their food. This was also true for the avian predator, for which hatching dates were not correlated with the peak availability of fledgling passerines. As a result, the match between food demand and availability deteriorated over time for both the passerines and the avian predators.These results could equally well be explained by consumers' insufficient responses as a consequence of constraints in adapting to climate change, or by them trying to escape predation from a higher trophic level, or both. Selection on phenology could thus be both from matches of phenology with higher and lower levels, and quantifying these can shed new light on why some organisms do adjust their phenology to climate change, while others do not.

International audience; 1. Several studies have shown that above- and belowground insects can interact by influencing each others growth, development, and survival when they feed on the same host-plant. In natural systems, however, insects can make choices on which plants to oviposit and feed. A field experiment was carried out to determine if root-feeding insects can influence feeding and oviposition preferences and decisions of naturally colonising foliar-feeding insects. 2. Using the wild cruciferous plant Brassica nigra and larvae of the cabbage root fly Delia radicum as the belowground root-feeding insect, naturally colonising populations of foliar-feeding insects were monitored over the course of a summer season. 3. Groups of root-infested and root-uninfested B. nigra plants were placed in a meadow during June, July, and August of 2006 for periods of 3 days. The root-infested and the root-uninfested plants were either dispersed evenly or placed in clusters. Once daily, all leaves of each plant were carefully inspected and insects were removed and collected for identification. 4. The flea beetles Phyllotreta spp. and the aphid Brevicoryne brassicae were significantly more abundant on root-uninfested (control) than on root-infested plants. However, for B. brassicae this was only apparent when the plants were placed in clusters. Host-plant selection by the generalist aphid M. persicae and oviposition preference by the specialist butterfly P. rapae, however, were not significantly influenced by root herbivory. 5. The results of this study show that the presence of root-feeding insects can affect feeding and oviposition preferences of foliar-feeding insects, even under natural conditions where many other interactions occur simultaneously. The results suggest that root-feeding insects play a role in the structuring of aboveground communities of insects, but these effects depend on the insect species as well as on the spatial distribution of the root-feeding insects.

Prey size was evaluated for seven passerine trans-Saharan migrant species at two spring stopover sites in Sardinia, Italy. The species considered were Pied Flycatcher Ficedula hypoleuca, Spotted Flycatcher Muscicapa striata, Redstart Phoenicurus phoenicurus, Garden Warbler Sylvia borin, Whitethroat Sylvia communis, Willow Warbler Phylloscopus trochilus and Wood Warbler Phylloscopus sibilatrix. The analysis was made for three prominent prey types: beetles (Coleoptera), ants (Hymenoptera: Formicidae) and "flying prey" (wasps and bees [Hymenoptera, excluding ants] and flies, Diptera, pooled), The prey size distribution in the diets of some species was very similar to that caught in our insect traps, showing that our estimates of availability are, at least partially, relevant, On the whole, diets deviated from food available in a species consistent way, The size distributions of "flying prey" differed between the two sites but were almost constant in the birds' diets, In contrast, size distributions of available beetles and ants at the sites were similar but were different in the birds' diets. Different feeding behaviour of the birds, in terms of physiological constraints during migratory stopovers, is discussed. Paired species comparisons show that the diets of most species differ significantly in the distribution of the size classes of at least some prey types, The conclusions drawn from the comparisons of the size distributions of all prey items collected from a bird species in one season are very similar to the conclusions drawn from comparisons based on the presence/absence of a size class per faecal sample. We compared the similarities of diet with and without using information on prey size, With the exception of the Pied Flycatcher and the Redstart at one of the study sites, size information did not add to diet segregation. Certain size classes within prey types tended to be common in the diet of these migrant passerines. However, specialization on certain size classes within broad taxonomic categories was not evident. [KEYWORDS: Trans-saharan migrants; habitat selection; competition; warblers; behavior; birds]

Nesting birds use several behavioural or physiological defence mechanisms against parasites. On Corsica, female blue tits Cyanistes caeruleus incorporate fresh fragments of a limited number of aromatic plants in the nest cup, from the end of nest construction until fledging. Some of these plants negatively affect bacterial growth and host location by blood-sucking mosquitoes in laboratory conditions. In natural populations, Corsican blue tit chicks are exposed to the highest levels of blood-sucking ectoparasitic blow flies Protocalliphora spp. reported in Europe. These ectoparasites can have severe negative effects on chick development and survival probabilities, especially when food constraints are elevated. Here we investigated in several natural Corsican blue tit populations the hypothesis that aromatic plants brought to the nest have anti-blow fly effects during the chick-rearing stage. We predicted that: 1) the amount of aromatic plants should be negatively related to blow fly infestation intensity across nests, 2) experimental addition of aromatic plants in nests should reduce blow fly infestation intensity, and 3) nestlings should be in better physical condition in nests where aromatic plants were experimentally added. No significant relation was found between amount of aromatic plants in nests and blow fly infestation intensity. Experimental addition of aromatic plants did not reduce blow fly infestation intensity and did not affect the chick phenotypic parameters we measured. We conclude that aromatic plants in blue tit nests are not used as a defence against ectoparasitic Protocalliphora blow flies in our study population.

Traits used in mate choice are often costly to produce or maintain, and thus can reflect an individual’s current condition. Mate choice, however, might not only be influenced by the current condition of a potential partner, but also by the condition it had experienced during its early development which can have strong and long-lasting effects on various traits. Here we studied the effects of different early developmental conditions, imposed by brood size manipulations (small, medium and large broods), on male attractiveness as measured by female choice experiments in zebra finches (Taeniopygia guttata). In three different experiments, we allowed females to choose between males that had been raised in different experimental brood sizes. In none of the experiments, females showed a significant preference for males which had experienced better developmental conditions, i.e. were raised in the relatively smaller experimental broods. Song rate was higher in males coming from small than large broods, but females did not prefer males that sang more. These results suggest that sexual attractiveness either was not affected by our experimental treatment or that males subsequently had compensated in their overall attractiveness for negative effects of early developmental conditions.

[KEYWORDS: birds; biting midges; blackflies; blood parasite-insect vector-vertebrate host relationships; Ceratopogonidae; Culicoides; distance to water sources; insecticide treatment; sampling methods; Simuliidae]

1. Although the ability to detect chemical cues is widespread in many organisms, it is surprising how little is known about the role of chemical communication in avian life histories. Nowadays, growing evidence suggests that birds can use olfaction in several contexts. However, we still do not know the role of bird olfaction in one of the most important determinants of survival, predator detection. 2. Blue tits, Cyanistes caeruleus L., were exposed to chemical cues of: (i) mustelid (predator), (ii) quail (odorous control); or (iii) water (odourless control) inside the nest-box where they were provisioning 8-day-old nestlings. 3. We show that blue tits were able to detect the chemical cues and showed antipredatory behaviours to cope with the risk of predation. Birds delayed their entry to the nest-box, and they perched on the hole of the nest-box and refused to enter more times when they found predator scent than control scents inside the nest-box. In addition, birds decreased the time spent inside the predator-scented nest-box when feeding nestlings. 4. The discovery of the ability of birds to use chemical cues of predators to accurately assess predation may help to understand many aspects of bird life histories that have been neglected until now.

The pivotal question in the debate on the ecological effects of climate change is whether species will be able to adapt fast enough to keep up with their changing environment. If we establish the maximal rate of adaptation, this will set an upper limit to the rate at which temperatures can increase without loss of biodiversity. The rate of adaptation will primarily be set by the rate of microevolution since (i) phenotypic plasticity alone is not sufficient as reaction norms will no longer be adaptive and hence microevolution on the reaction norm is needed, (ii) learning will be favourable to the individual but cannot be passed on to the next generations, (iii) maternal effects may play a role but, as with other forms of phenotypic plasticity, the response of offspring to the maternal cues will no longer be adaptive in a changing environment, and (iv) adaptation via immigration of individuals with genotypes adapted to warmer environments also involves microevolution as these genotypes are better adapted in terms of temperature, but not in terms of, for instance, photoperiod. Long-term studies on wild populations with individually known animals play an essential role in detecting and understanding the temporal trends in life-history traits, and to estimate the heritability of, and selection pressures on, life-history traits. However, additional measurements on other trophic levels and on the mechanisms underlying phenotypic plasticity are needed to predict the rate of microevolution, especially under changing conditions. Using this knowledge on heritability of, and selection on, life-history traits, in combination with climate scenarios, we will be able to predict the rate of adaptation for different climate scenarios. The final step is to use ecoevolutionary dynamical models to make the link to population viability and from there to biodiversity loss for those scenarios where the rate of adaptation is insufficient.

Despite the fact that in many bird species offspring are provisioned by two parents, few studies to date have examined the implications of biparental care for offspring solicitation behaviour. Male and female parents can differ in their potential value to individual offspring if they follow different allocation rules and/or have different provisioning rates. If such differences occur, offspring should use different rules when soliciting to the male and female parent. This study looked at how the begging behaviour of nestling blue tits, Cyanistes caeruleus, is influenced by their hunger, size and by the sex of the provisioning adult. Nestling hunger was manipulated across size ranks, using periods of hand feeding or food deprivation. While nestling hunger influenced all aspects of nestling begging behaviour, nestling size and the sex of the provisioning adult only affected the position of nestlings in the nest cup. When hungry, nestlings moved closer to the male parent and the largest nestlings in a brood primarily obtained the closest positions. This may be the result of offspring responding to a difference between the sexes in parental food allocation rules.

The ecology of a species and its communication system require mutual adaptations. Specifically, information transfer between individuals needs to be adapted to the social and ecological requirements and constraints. As a consequence, constraints on signal transmission are likely to play a role in the evolution of spatiotemporal behavior and settlement and vice versa. In long-distance signaling, such as in bird song, adaptations can be reflected in specific signal structures that transmit to a socially relevant distance without degradation masking the coded information. Here, we studied sound transmission properties of 2 different song components in male nightingale (Luscinia megarhynchos) territorial song, i.e., transmission of whistle songs and songs with rapid broadband trills. We also determined spacing of nocturnal song posts using a global positioning system. The results revealed highly significant differences in transmission of the 2 functionally different song traits, with information in whistles traveling well beyond the typical spacing between neighboring individuals. Information coded in trills bandwidth did not even travel the average distance toward the nearest neighbor, showing that information coded in trill bandwidth is not available for receivers at typical spacing distances. The results emphasize that for a better understanding of evolutionary processes in communication, ecological components such as spatial distance as well as signal structure and signal degradation have to be taken into account. Copyright 2008, Oxford University Press.

Almost all life histories are phenotypically plastic: that is, life-history traits such as timing of breeding, family size or the investment in individual offspring vary with some aspect of the environment, such as temperature or food availability. One approach to understanding this phenotypic plasticity from an evolutionary point of view is to extend the optimality approach to the range of environments experienced by the organism. This approach attempts to understand the value of particular traits in terms of the selection pressures that act on them either directly or owing to trade-offs due to resource allocation and other factors such as predation risk. Because these selection pressures will between environments, the predicted optimal phenotype will too. The relationship expressing the optimal phenotype for different environments is the optimal reaction norm and describes the optimal phenotypic plasticity. However, this view of phenotypic plasticity ignores the fact that the reaction norm must be underlain by some sort of control system: cues about the environment must be collected by sense organs, integrated into a decision about the appropriate life history, and a message sent to the relevant organs to implement that decision. In multicellular animals, this control mechanism is the neuroendocrine system. The central question that this paper addresses is whether the control system affects the reaction norm that evolves. This might happen in two different ways: first, the control system will create constraints on the evolution of reaction norms if it cannot be configured to produce the optimal reaction norm and second, the control system will create additional selection pressures on reaction norms if the neuroendocrine system is costly. If either of these happens, a full understanding of the way in which selection shapes reaction norms must include details of the neuroendocrine control system. This paper presents the conceptual framework needed to explain what is meant by a constraint or cost being created by the neuroendocrine system and discusses the extent to which this occurs and some possible examples. The purpose of doing this is to encourage endocrinologists to take a fresh look at neuroendocrine mechanisms and help identify the properties of the system and situations in which these generate constraints and costs that impinge on the evolution of phenotypic plasticity.

The loss and fragmentation of forest habitats have been considered to pose a worldwide threat to the viability of forest-dwelling animals, especially to species that occupy old forests. We investigated whether the annual survival of sedentary male Tengmalm's owls Aegolius funereus was associated with the cover of old coniferous forests in Finland. Survival and recapture probabilities varied annually with density changes in populations of the main prey (Microtus voles). When this variation was controlled for, and relationships between survival and proportions of the three different forest age classes (old-growth, middle-aged, and young) were modeled separately, the old-growth model was the most parsimonious. Survival increased with the cover of old forest, although the extent of old forest within owl territories was relatively small (mean approximately 12%, range 2-37%). This association, however, varied among years and appeared especially in years of increasing vole abundance. At such times, old forests may sustain high populations of bank voles Clethrionomys glareolus, shrews and small passerines. In addition, old forests may serve as refuges against large avian predator species, such as Ural owls Strix uralensis and goshawks Accipiter gentilis. Our results suggest that changes in habitat quality created by agriculture and forestry may have the potential to reduce adult survival, an essential component of fitness and population viability.

Multiple advertising sexual traits may either advertise different characteristics of male condition or be redundant to reinforce reliability of signals. Research has focused on multiple visual traits. However, in animals that use different multiple additional sensory systems, such as chemoreception, different types of traits might have evolved to signal similar characteristics of a male quality using different sensory channels. We examined whether ventral coloration and chemicals in femoral gland secretions of male common wall lizards, Podarcis muralis, are affected by their health state (blood-parasite load and cell-mediated immune response). Our results indicated that less parasitized lizards had brighter and more yellowish ventral colorations and also femoral secretions with higher proportions of two esters of octadecenoic acid. In addition, lizards with a greater immune response had more saturated coloration and secretions with higher proportions of octadecenoic acid methyl ester. We suggest that these signals would be reliable because only healthier males seemed able to allocate more carotenoids to coloration and presumably costly chemicals to secretions. The use of multiple sensory channels may provide more opportunities to signal a male quality under different circumstances, but also may reinforce the reliability of the signal when both types of traits may be perceived simultaneously.

We applied a phenotypic QST (PST) vs. FST approach to study spatial variation in selection among great snipe (Gallinago media) populations in two regions of northern Europe. Morphological divergence between regions was high despite low differentiation in selectively neutral genetic markers, whereas populations within regions showed very little neutral divergence and trait differentiation. QST > FST was robust against altering assumptions about the additive genetic proportions of variance components. The homogenizing effect of gene flow (or a short time available for neutral divergence) has apparently been effectively counterbalanced by differential natural selection, although one trait showed some evidence of being under uniform stabilizing selection. Neutral markers can hence be misleading for identifying evolutionary significant units, and adopting the PST–FST approach might therefore be valuable when common garden experiments is not an option. We discuss the statistical difficulties of documenting uniform selection as opposed to divergent selection, and the need for estimating measurement error. Instead of only comparing overall QST and FST values, we advocate the use of partial matrix permutation tests to analyse pairwise QST differences among populations, while statistically controlling for neutral differentiation.

Deforestation may increase predation risk for prey because it may make prey more conspicuous and limit the number of refuges suitable to avoid predators. Therefore, prey may need to increase the magnitude of escape responses. However, excessive antipredatory effort might lead to a loss of body mass and a decrease in defense against parasites, with important consequences for short- and long-term fitness. We analyzed whether Psammodromus algirus (L., 1758) lizards that inhabit patches with different levels of deterioration of the vegetation within the same oak forest differed in relative abundance numbers, microhabitat use, antipredatory strategies, and health state. Results showed lizards selected similar microhabitats regardless of the level of deterioration of the vegetation and relative abundance of lizards was similar in both areas. However, habitat deterioration seemed to increase predation risk, at least for females, because they were detected at longer distances in deteriorated areas. Females seemed to adjust their antipredatory behavior accordingly to high risk of predation by increasing approach distances allowed to predators. The costs associated with frequent antipredatory displays might explain why females in deteriorated habitats had lower body condition and greater blood parasite loads than females in natural areas. This loss of body condition and increased parasitemia might have deleterious consequences for female fitness and therefore affect the maintenance of lizard populations in the long-term.

The exciting discovery by Hubert Schwabl (Washington State University) in the early nineties that the yolk of bird eggs contains hormones originating from the mother opened up an extremely successful research area for endocrinologists and behavioral ecologists. Since then, knowledge of both the factors that influence the amount of hormones deposited in yolk by the female, and the consequences of exposure to these maternal hormones on offspring growth, physiology, and behaviour has accumulated rapidly. The field has been dominated by the idea that mothers use yolk hormones to adaptively adjust offspring development in their interest. However, this idea neglects that the (evolutionary) interests of mother and offspring may differ. Each offspring will try to maximize its share of parental investment while the mother wants to distribute her investment among all her offspring. When there is such parent-offspring conflict the offspring are selected to respond to the yolk hormones in a way that is b Parent-offspring conflict is not the only intra-familial strife that may shape the evolution of yolk hormone deposition. Parents disagree (evolutionarily) over the amount of care each of them is willing to provide to their young. Since yolk hormones affect offspring begging behavior, females may be able to use yolk hormone deposition to modify begging traits in a way that increases the amount of parental care provided by the male. The existence of sex differences in response to offspring begging The authors therefore suggest that for a full understanding of the evolution of hormone-mediated maternal effects it is essential to study both fitness consequences, and physiological mechanisms and constraints, from the perspective of all family members. Furthermore, the authors believe that the integration of evolutionary biology and endocrinology will lead to the most rapid advance in this field - from both an evolutionary and endocrinological point of view. It may therefore not be coincidenc

1. During the last centuries, the breeding range of the great snipe Gallinago media has declined dramatically in the western part of its distribution. To examine present population dynamics in the Scandinavian mountains, we collected and analysed a 19-year time series of counts of great snipe males at leks in central Norway, 1987-2005.2. The population showed large annual fluctuations in the number of males displaying at lek sites (range 45-90 males at the peak of the mating season), but no overall trend.3. We detected presence of direct density-dependent mechanisms regulating this population. Inclusion of the density-dependent term in a Ricker-type model significantly improved the fit with observed data (evaluated with Parametric Bootstrap Likelihood Ratio tests and Akaike's Information Criterion for small sample size).4. An analysis of (a number of a priori likely) environmental covariates suggests that the population dynamics were affected by conditions influencing reproduction and survival of offspring during the summer, but not by conditions influencing survival at the wintering grounds in Africa. This is in contrast to many altricial birds breeding in the northern hemisphere, and supports the idea that population dynamics of migratory nidifugous birds are more influenced by conditions during reproduction.5. Inclusion of these external factors into our model improved the detectability of density dependence. This illustrates that allowing for external effects may increase statistical power of density dependence tests and thus be of particular importance in relatively short time series.6. In our best model of the population dynamics, two likely density-independent offspring survival covariates explained 47.3% of the variance in great snipe numbers (predation pressure estimated by willow grouse reproductive success and food availability estimated by the amount of precipitation in June), whereas density dependence explained 35.5%. Demographic stochasticity and unidentified environmental stochasticity may account for the remaining 17.2%. published

Polymorphisms in several neurotransmitter-associated genes have been associated with variation in human personality traits. Among the more promising of such associations is that between the human dopamine receptor D4 gene ( Drd4 ) variants and novelty-seeking behaviour. However, genetic epistasis, genotype–environment interactions and confounding environmental factors all act to obscure genotype–personality relationships. Such problems can be addressed by measuring personality under standardized conditions and by selection experiments, with both approaches only feasible with non-human animals. Looking for similar Drd4 genotype–personality associations in a free-living bird, the great tit ( Parus major ), we detected 73 polymorphisms (66 SNPs, 7 indels) in the P. major Drd4 orthologue. Two of the P. major Drd4 gene polymorphisms were investigated for evidence of association with novelty-seeking behaviour: a coding region synonymous single nucleotide polymorphism (SNP830) and a 15 bp indel (ID15) located 5′ to the putative transcription initiation site. Frequencies of the three Drd4 SNP830 genotypes, but not the ID15 genotypes, differed significantly between two P. major lines selected over four generations for divergent levels of ‘early exploratory behaviour’ (EEB). Strong corroborating evidence for the significance of this finding comes from the analysis of free-living, unselected birds where we found a significant association between SNP830 genotypes and differing mean EEB levels. These findings suggest that an association between Drd4 gene polymorphisms and animal personality variation predates the divergence of the avian and mammalian lineages. Furthermore, this work heralds the possibility of following microevolutionary changes in frequencies of behaviourally relevant Drd4 polymorphisms within populations where natural selection acts differentially on different personality types.

Global climate change is having a major impact on the viability of species. Whether a particular population will survive or go extinct will depend on its potential to adapt to new environmental conditions. In migratory birds, the timing of spring migration is one of the major determinants of the timing of reproduction and as spring temperatures increase, we expect birds to return earlier to their breeding grounds. In accord with this expectation, the timing of spring arrival has advanced in many bird populations within the last 30 years. Yet, despite the presence of genetic variation in the timing of migration and fitness advantages in birds arriving early we still lack conclusive evidence for evolutionary change. One reason for this may be that weather conditions en route, particular the direction and speed of winds, have an important influence on individual migration speed. Moreover, there is strong evidence that physical condition may modify the timing of departure from the wintering grounds, migration speed and ultimately the timing of arrival and breeding. We also expect nestling condition and maternal effects to influence spring migration timing. Long-term population studies monitoring individual arrival in combination with experimental approaches will be needed to tease apart genetic and different environmental effects on the traits determining migration timing. This knowledge will be crucial for predicting adaptive responses of the timing of spring arrival in the future.

For many leaf-feeding herbivores, synchrony in phenology with their host plant is crucial as development outside a narrow phenological time window has severe fitness consequences. In this review, we link mechanisms, adaptation, and population dynamics within a single conceptual framework, needed for a full understanding of the causes and consequences of this synchrony. The physiological mechanisms underlying herbivore and plant phenology are affected by environmental cues, such as photoperiod and temperature, although not necessarily in the same way. That these different mechanisms lead to synchrony, even if there is spatial and temporal variation in plant phenology, is a result of the strong natural selection acting on the mechanism underlying herbivore phenology. Synchrony has a major impact on the population densities of leaf-feeding Lepidoptera, and years with a high synchrony may lead to outbreaks. Global climate change leads to a disruption of the synchrony between herbivores and their host plants, which may have major impacts for population viability if natural selection is insufficient to restore synchrony.

Evolutionary conflicts of interest between family members are expected to influence patterns of parental investment. In altricial birds, despite providing the same kind of parental care, patterns of investment in different offspring can differ between parents, a situation termed parentally biased favoritism. Previous explanations for parentally biased favoritism have received mixed theoretical and empirical support. Here, we test the prediction that in blue tits, Cyanistes caeruleus, females bias their food allocation rules to favor the smallest offspring during the nestling stage. By doing so, females could increase the subsequent amount of paternal care supplied by their partner during the fledging period, as a previous study showed that males feed the largest fledglings. When size differences within the brood are less pronounced, all offspring will require similar amounts of postfledging care, and thus, the male parent will lose the advantage of caring for the largest offspring that are closest to independence. In this study, we controlled the hunger of the smallest and largest nestlings in the brood and compared the food allocation rules of the 2 parents. We found that the male parent had a stronger preference than the female to feed the closest nestlings and made no distinction between nestlings based on size, whereas the female provisioned small hungry nestlings more when they were at intermediate distances from her. These differences in parental food allocation rules are consistent with predictions based on sexual conflict over postfledging parental investment. Copyright 2007, Oxford University Press.

There is burgeoning interest in the costs of mating and in how this leads to sex differences in the optimal mating rate. Here, we attempt to look beyond an exclusive focus on matings to examine the fundamental conflicts that arise out of the fact that sexual reproduction involves investment in offspring by typically unrelated individuals. Conflicts between mates stem from the ever present potential for individuals to reduce their investment relative to that of their sexual partner in order to seek alternative reproductive opportunities elsewhere. All aspects of life histories, the partitioning of time and energy into growth, survival and reproduction, are inextricably caught up in, and moulded by these conflicts of interest, the most profound expression of which is the differentiation between male and female types. This differentiation creates a new set of conflicts because alleles with positive effects on fitness when expressed in one sex may have negative fitness effects in the other. This type of conflict may influence the evolution of separate juvenile and adult life stages as in metamorphosis, although a major outstanding question is why sex limitation does not evolve more rapidly. We review the impact of conflicts of interest between males and females on all aspects of life history, revealing at least as much evidence for sexual conflict over life history traits such as investment in gametes and parental care as there is for conflicts over matings.

Evolutionary change results from selection acting on genetic variation. For migration to be successful, many different aspects of an animal’s physiology and behaviour need to function in a co-coordinated way. Changes in one migratory trait are therefore likely to be accompanied by changes in other migratory and life-history traits. At present, we have some knowledge of the pressures that operate at the various stages of migration, but we know very little about the extent of genetic variation in various aspects of the migratory syndrome. As a consequence, our ability to predict which species is capable of what kind of evolutionary change, and at which rate, is limited. Here, we review how our evolutionary understanding of migration may benefit from taking a quantitative-genetic approach and present a framework for studying the causes of phenotypic variation. We review past research, that has mainly studied single migratory traits in captive birds, and discuss how this work could be extended to study genetic variation in the wild and to account for genetic correlations and correlated selection. In the future, reaction-norm approaches may become very important, as they allow the study of genetic and environmental effects on phenotypic expression within a single framework, as well as of their interactions. We advocate making more use of repeated measurements on single individuals to study the causes of among-individual variation in the wild, as they are easier to obtain than data on relatives and can provide valuable information for identifying and selecting traits. This approach will be particularly informative if it involves systematic testing of individuals under different environmental conditions. We propose extending this research agenda by using optimality models to predict levels of variation and covariation among traits and constraints. This may help us to select traits in which we might expect genetic variation, and to identify the most informative environmental axes. We also recommend an expansion of the passerine model, as this model does not apply to birds, like geese, where cultural transmission of spatio-temporal information is an important determinant of migration patterns and their variation. [KEYWORDS: Individual variation ; Migration ; Migratory syndrome ; Migratory traits ; Quantitative genetics]

The ability to predict individual breeding values in natural populations with known pedigrees has provided a powerful tool to separate phenotypic values into their genetic and environmental components in a nonexperimental setting. This has allowed sophisticated analyses of selection, as well as powerful tests of evolutionary change and differentiation. To date, there has, however, been no evaluation of the reliability or potential limitations of the approach. In this article, I address these gaps. In particular, I emphasize the differences between true and predicted breeding values (PBVs), which as yet have largely been ignored. These differences do, however, have important implications for the interpretation of, firstly, the relationship between PBVs and fitness, and secondly, patterns in PBVs over time. I subsequently present guidelines I believe to be essential in the formulation of the questions addressed in studies using PBVs, and I discuss possibilities for future research. [KEYWORDS: accuracy ; animal model ; BLUP ; heritability ; natural population ; natural selection ; pedigree ; reliability ; selection differential ; selection gradient]

1. In birds, early breeding individuals generally reproduce more successfully than late breeding individuals. The lack of response to this selection could be explained by resource constraints during the egg production period. 2. Parus species can learn from the mismatch experienced between breeding time and nestling food availability and subsequently adjust their breeding time accordingly. In two Great Tit populations, breeding time was manipulated by creating an artificial food peak. This allowed us to study fitness consequences of manipulated breeding time in the following year without the confounding effects of food supplementation. 3. In one population, manipulated females advanced their laying dates in response to the artificial food peak. However, sample sizes were too low to quantify fitness consequences. In the other population, no response to the treatment was found. This difference could be caused by differences in resource availability in early spring between the two habitats. Low resource availability in early spring could also explain the lack of response to selection observed in one population [KEYWORDS: Climate change ; food supplementation ; Parus major ; resource constraints ; selection on breeding time]