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Joost M Tinbergen - One of the best experts on this subject based on the ideXlab platform.
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biased estimates of fitness consequences of Brood Size manipulation through correlated effects on natal dispersal
Journal of Animal Ecology, 2005Co-Authors: Joost M TinbergenAbstract:Summary 1. Dispersal of parents and offspring in relation to manipulated Brood Size were analysed in the great tit Parus major (L.) to study the potential confusion between dispersal and survival. The study area consisted of eight woodlots interspersed with nonbreeding habitat. The maximum distance between nestboxes was 10 km. 2. The Brood Size of pairs with similar clutch Size and laying date was manipulated in 3 years when chicks were 2 days old (1995, 1997 and 1998). Three nestlings were removed from one and added to another Brood while a third was kept as a control. Offspring were measured, weighed and marked and breeding birds were captured and marked to allow dispersal estimates. 3. For the offspring, dispersal was estimated as the distance between the natal nestbox and the nestbox of first breeding (natal dispersal distance) and, for the parents, as the distance between breeding boxes in two subsequent seasons (breeding dispersal distance). 4. Natal dispersal distance was positively affected by Brood Size manipulation. This effect was more pronounced in males than in females. Breeding dispersal distance was not affected by manipulation. 5. The practical consequence of this finding is that fitness estimates used to measure selection on Brood Size did depend on the spatial scale of the study area. For the Lauwersmeer population measured selection pressure changed from positive to stabilizing when I restricted the spatial scale of recovery. Other Brood Size manipulation experiments may suffer from similar biases in their fitness estimates. 6. The biological consequence of this finding is that, if clutch Size has a heritable component, local adaptation of clutch Size will depend on the spatial heterogeneity of the habitat.
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strong evidence for selection for larger Brood Size in a great tit population
Behavioral Ecology, 2004Co-Authors: Joost M Tinbergen, Juan Jose SanzAbstract:We measured the selection pressure on Brood Size in a recently established population of great tits (Parus major L.) in the northern Netherlands by manipulating Brood Size in three years (1995: n e 51, 1997: n e 66, 1998: n e 51), and we estimated fitness consequences in terms of local survival of both offspring and parents. Enlarged Broods had highest fitness; the offspring fitness component was positively affected by manipulation and the parental fitness component was unaffected. Parental survival and the probability that parents produced a second clutch were not affected by the treatment. However, parents that had raised enlarged Broods produced their second clutch later in the season. Clutch Size, Brood Size, and laying date of birds recaptured in the next breeding season were largely independent of the treatment. We conclude that there is strong evidence for selection for larger Brood Size and reject the individual optimization hypothesis for this population because the number of young in the nest predicts fitness independently of the manipulation history. Copyright 2004.
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energy expenditure nestling age and Brood Size an experimental study of parental behavior in the great tit parus major
Behavioral Ecology, 1999Co-Authors: Juan Jose Sanz, Joost M TinbergenAbstract:A Brood manipulation experiment on great tits Parus major was performed to study the effects of nestling age and Brood Size on parental care and offspring survival. Daily energy expenditure (DEE) of females feeding nestlings of 6 and 12 days of age was measured using the doubly-labeled water technique. Females adjusted their Brooding behavior to the age of the young. The data are consistent with the idea that Brooding behavior was determined primarily by the thermoregulatory requirements of the Brood. Female DEE did not differ with nestling age; when differences in body mass were controlled for, it was lower during the Brooding period than later. In enlarged Broods, both parents showed significantly higher rates of food provisioning to the Brood. Female DEE was affected by Brood Size manipulation, and it did not level off with Brood Size. There was no significant effect of nestling age on the relation between DEE and manipulation. Birds were able to raise a larger Brood than the natural Brood Size, although larger Broods suffered from increased nestling mortality rates during the peak demand period of the nestlings. Offspring condition at fledging was negatively affected by Brood Size manipulation, but recruitment rate per Brood was positively related to Brood Size, suggesting that the optimal Brood Size exceeds the natural Brood Size in this population. Key words: Brood Size manipulation, doubly-labeled water technique, energy expenditure, great tits, parental care, Parus major. [Behav Ecol 10:598‐606 (1999)]
Heinz Richner - One of the best experts on this subject based on the ideXlab platform.
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physiological responses to increased Brood Size and ectoparasite infestation adult great tits favour self maintenance
Physiology & Behavior, 2015Co-Authors: Michele Wegmann, Beatrice Voegeli, Heinz RichnerAbstract:Abstract Different types of stressors trigger responses of different physiological systems, and these responses may contribute differentially to the maintenance of homeostasis, to trade-offs and the evolution of life-history traits. To manipulate two common stressors during reproduction, we infested half of the nests in a naturally breeding great tit population with ectoparasites and simultaneously manipulated Brood Size, using a 2 × 2 experimental design. Parents in this model species commonly compensate for ectoparasites by an increase in food provisioning. We assessed parental responses to these concurrent stressors by measuring several physiological stress parameters such as changes in metabolic rate, oxidative stress and expression of heat-shock proteins (Hsp), and explored how these stressors affect the trade-off between self-maintenance and reproduction. Neither flea infestation nor Brood Size manipulation affected adult metabolic rate, oxidative damage or Hsp levels. Furthermore, we found no interactive effect of the two treatments on adults. However, nestlings in infested nests had lower body mass and lower survival. Nestlings in enlarged Broods were lighter and had lower survival, although parents of enlarged Broods increased food provisioning rate. The findings suggest that adults favour maintenance of cellular homeostasis, and physiological equilibrium over current reproduction, and that the costs induced by both stressors, flea infestation and increased Brood Size, are carried by the offspring. It emphaSizes the importance of self-maintenance over reproduction in life-history decisions, and more generally the need of including physiological traits for understanding the evolution of life-histories.
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Brood Size sibling competition and the cost of begging in great tits parus major
Behavioral Ecology, 2003Co-Authors: Samuel Neuenschwander, Martin W G Brinkhof, Mathias Kolliker, Heinz RichnerAbstract:Evolutionary theory of parent-offspring conflict explains begging displays of nestling birds as selfish attempts to influence parental food allocation. Models predict that this conflict may be resolved by honest signaling of offspring need to parents, or by competition among nestmates, leading to escalated begging scrambles. Although the former type of models has been qualitatively supported by experimental studies, the potential for a begging component driven by scramble competition cannot be excluded by the evidence. In a Brood-Size manipulation experiment with great tits, Parus major, we explored the scramble component in the begging activity of great tit nestlings by investigating the mechanisms of sibling competition in relation to Brood Size. While under full parental compensation, the feeding rate per nestling will remain constant over all Brood Sizes for both types of models; the scramble begging models alone predict an increase in begging intensity with Brood Size, if begging costs do not arise exclusively through predation. Great tit parents adjusted feeding rates to Brood Size and fed nestlings at similar rates and with similar prey Sizes in all three Brood-Size categories. Despite full parental compensation, the begging and food solicitation activities increased with experimental Brood Size, whereas nestling body condition deteriorated. These findings support a scramble component in begging and suggest that the competition-induced costs of food solicitation behavior play an important role in the evolution of parent-offspring communication. Copyright 2003.
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are clutch and Brood Size patterns in birds shaped by ectoparasites
Oikos, 1995Co-Authors: Heinz Richner, Philipp HeebAbstract:Ectoparasites may influence the optimum values of important life history traits such as clutch Size and Brood Size by having different fitness effects for large and for small trait values. We propose here that the life-cycle length of the common ectoparasite species of a host determines whether it is more profitable for the host to raise a large or a small Brood. The hypothesis rests on the following argument: (1) the length of an ectoparasite's life-cycle relative to the timespan that the host nestlings are available as a resource determines the total parasite load per nest during the nestlings' growth phase, and therefore (2) also the parasite load per nestling, which in turn (3) determines the parasite impact on the nestlings. Populations of long-cycled ectoparasites (i.e. the life-cycle length of the ectoparasite is similar to the length of time that nestlings take from hatching to fledging) do not build up considerably during the nestling phase and, consequently, parasites become increasingly diluted with an increase in Brood Size. This predicts no correlation between parasite load and Brood Size, but a negative correlation between parasite load per nestling and Brood Size. Larger Broods will be favoured and Brood Size should be reduced only when feeding conditions become increasingly inadequate. In contrast, populations of short-cycled ectoparasites (i.e. the life-cycle length of the ectoparasite is much shorter than the length of time that nestlings take from hatching to fledging) can build up quickly and may reach the carrying capacity given by the number of host nestlings. This predicts a positive correlation between parasite load and Brood Size, but no correlation between parasite load per nestling and Brood Size. Smaller Broods may then be at an advantage because they can be more adequately provisioned with food. Whether females should adjust clutch Size will largely depend on whether they can, when laying their clutch, predict the parasite load after hatching. When future infestation can be predicted, females of species that are commonly infested with short-cycled ectoparasites should lay a smaller clutch, but females commonly infested with long-cycled parasites should lay a larger clutch. When future infestation cannot be predicted at laying, with shortcycled ectoparasites, females should lay a normal clutch and reduce it when the nest becomes infested, but with longcycled ectoparasites, females should lay a larger clutch and maintain Brood Size as long as feeding conditions are adequate. If parasite pressure is constant over many breeding season, we may expect selection for smaller or larger clutches depending on the cycle length of the common ectoparasite. If parasite pressure fluctuates stochastically, a behavioural response will be more appropriate. Patterns from intraand interspecific studies are in agreement with most predictions outlined above. Clutch Size in birds varies widely both among and within species and much of this variation has been attributed proximately to variance in phenotypic quality of the parents, variance in food abundance, nest predation, nestling competition, nest parasitism by other birds, phylogenetic inertia, physiological constraints, and ectoparasites (for recent reviews see e.g. Murphy and Haukioja 1986, Godfray et al. 1991, Poiani 1993a, b). Ultimately much of this variation can be understood in terms of variation in reproductive trade-offs, such as clutch Size with offspring or adult survival and fecundity (for reviews see Linden and M0ller 1989, Dijkstra et al. 1990, Stearns 1992). Ectoparasites can strongly reduce reproductive success (Moss and Camin 1970, M0ller et al. 1990, M0ller 1993, Richner et al. 1993, Clayton and Tompkins 1994) of their hosts, and are therefore most likely to affect reproductive trade-offs. This life-history point of view predicts that hosts may reduce the impact of parasites by altering their own reproductive effort (Forbes 1993, Poulin et al. 1994). In this note we address the question of how ectoparasites are expected to influence Brood Size by considering (1) the relationship between life-cycle length of ectoparasites, host Brood Size and parasite load, (2) the expected relationship between life-cycle length of ectoparasites and the effect of ectoparasites on nestlings of small and large Broods, (3) the expected host response in terms of a change in clutch Size and Brood Size. Empirical evidence supporting the predictions are presented.
Ch Dekogel - One of the best experts on this subject based on the ideXlab platform.
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long term effects of Brood Size manipulation on morphological development and sex specific mortality of offspring
Journal of Animal Ecology, 1997Co-Authors: Ch DekogelAbstract:1. Little is known about long-term effects of Brood Size on fitness components of offspring. This is unfortunate because such information is needed to predict optimal Brood Size. Furthermore, ontogenetic circumstances are potentially important in explaining the large individual differences in lifetime reproductive success documented in many species. 2. In a laboratory study the long-term effect of Brood Size manipulation on mortality and morphological development of offspring was investigated. Young zebra finches Taeniopygia guttata were reared in small or large Broods. Young were exchanged in such a way that natural siblings from different rearing conditions could be compared. 3. Manipulated Brood Size affected offspring morphology permanently (measurements were taken up to the age of 12 months). Individuals reared in small Broods were heavier, had longer tarsi and wings, higher beaks, were in better condition, and males had redder beaks. The experiment did not affect beak length or female beak redness. Individuals from large Broods had caught up on wing length and males from large Broods on beak redness by 6 months of age, which may reflect priority of investment in traits important to fitness. 4. Mortality of offspring raised in large Broods was higher both before and after independence. After independence the effect of manipulated Brood Size on mortality was sex specific; females were most likely to die. This suggests that the optimal sex ratio of offspring may depend on Brood Size. 5. The effect of Brood Size on mortality after independence was probably partly mediated by Size and condition during the nestling phase and possibly by peer aggression among adult offspring. Sex-linked mortality could not be explained by a sex difference in morphological development. Why females are more vulnerable remains to be discovered.
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Costs of reproduction in the Zebra Finch Taeniopygia guttata : Manipulation of Brood Size in the laboratory
Journal of Avian Biology, 1996Co-Authors: Ch Dekogel, Gerard OverkampAbstract:Brood Size of Zebra Finches Taeniopygia guttata was manipulated in an attempt to identify a trade-off between current and subsequent reproduction in a laboratory situation with ad libitum food availability. The birds were able to raise a larger Brood than the most frequent Brood Size under the same conditions. Initiation of the subsequent clutch was advanced after raising a small Brood, and delayed after raising a large Brood. The Size of the subsequent clutch was not affected by the previous, experimental Brood Size. Thus, a cost of reproduction was observed in modification of the reproductive interval. Brood Size also affected the prospects of the current, experimental Brood. Both nestling survival and nestling weight at independence decreased with Brood Size. It has often been suggested that food availability limits reproduction in the field. This study shows that under unrestricted access to food, other factors restrain reproduction. Time allocation, energy expenditure and nutrient reserves of the parents are discussed as potential alternative constraints.
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effects of Brood Size manipulations on sexual attractiveness of offspring in the zebra finch
Animal Behaviour, 1996Co-Authors: Ch Dekogel, H J PrijsAbstract:Abstract In a laboratory study the effect of Brood Size manipulations on the sexual attractiveness of offspring was investigated. Zebra finches,Taeniopygia guttata, were reared in small or large Broods. Young were exchanged so that natural siblings from different rearing conditions could be compared. Birds of both sexes reared in small Broods were larger and heavier as adults; furthermore, they developed the adult bill colour sooner than birds reared in large Broods. Males reared in small Broods had a redder beak as adults. Males but not females reared in small Broods were more attractive to opposite sex individuals, as measured in choice tests. Males with redder beaks were more attractive to females. No relation was found in females between attractiveness and measured traits. Sexual attractiveness may thus be a potentially important mechanism by which Brood Size affects fitness.
Jonathan Wright - One of the best experts on this subject based on the ideXlab platform.
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provisioning tactics of great tits parus major in response to long term Brood Size manipulations differ across years
Behavioral Ecology, 2017Co-Authors: Kimberley J Mathot, Jonathan Wright, Annelise Olsen, Ariane Mutzel, Yimen Gerardo Arayaajoy, Marion Nicolaus, David F Westneat, Bart Kempenaers, Niels J DingemanseAbstract:Parents provisioning their offspring can adopt different tactics to meet increases in offspring demand. In this study, we experimentally manipulated Brood demand in free living great tits (Parus major) via Brood Size manipulations and compared the tactics adopted by parents in 2 successive years (2010 and 2011) with very different ecological conditions. In 2011, temperatures were warmer, there were fewer days with precipitation, and caterpillars (the preferred prey of great tits) made up a significantly larger proportion of the diet. In this "good" year, parents responded to experimental increases in Brood demand by decreasing mean inter-visit intervals (IVIs) and reducing prey selectivity, which produced equal average long-term delivery of food to nestlings across the Brood Size treatments. In 2010, there was no evidence for effects of Brood Size manipulations on mean IVIs or prey selectivity. Consequently, nestlings from enlarged Broods experienced significantly lower long-term average delivery rates compared with nestlings from reduced Broods. In this "bad" year, parents also exhibited changes in the variance in inter-visit intervals (IVIs) as a function of treatment that were consistent with variance-sensitive foraging theory: variance in IVIs tended to be lowest for reduced Broods and highest for enlarged Broods. Importantly, this pattern differed significantly from that observed in the "good" year. We therefore found some support for variance-sensitive provisioning in the year with more challenging ecological conditions. Taken together, our results show that variation in Brood demand can result in markedly different parental foraging tactics depending on ecological conditions.
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biparental care short term manipulation of partner contribution and Brood Size in the starling sturnus vulgaris
Behavioral Ecology, 1990Co-Authors: Jonathan Wright, Innes C CuthillAbstract:© 1990 International Society for Behavioral Ecology In species with biparental care, the evolutionarily stable investment strategy depends, among other factors, on the reproductive value of the Brood and on the contribution of one's partner. A shortfall in work rate by one parent should be partially compensated for by its partner, while both parents should invest more effort when there are more young. We simultaneously tested these predictions by attaching weights to one member of pairs of European starlings (Sturnus vulgaris), thus reducing one partner's nest visitation rate, and by daily manipulation of Brood Sizes (between three and seven chicks). Both sexes compensated to an equivalent degree for their partner's lower work rate, while at the same time adjusting flexibly to the daily Brood Size changes by increasing visit rates to larger Broods. However, this ability to compensate was limited in the larger Brood Sizes, perhaps due to an upper limit on provisioning rate. Weighted birds and their partners showed differences in prey types delivered, relative to controls, taking a lower proportion of leatherjackets. With regard to the proximate cues affecting parental provisioning rate, begging noise levels (automatically recorded by computer from microphones in the nest-box) increased with Brood Size, but average length of begging bout did not. As expected, visit rates per chick decreased as Brood Size increased, and this was reflected in lower weight gains per day by chicks in larger Broods. These results agree in general with games theory models but reveal important departures from our previous work with respect to (1) parents reaching an apparent ceiling to nest visitation rate at high Brood Sizes and (2) the ability to track these Brood demands with short-term adjustments. [Behav Ecol 1990; 1:116-124]
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manipulation of sex differences in parental care the effect of Brood Size
Animal Behaviour, 1990Co-Authors: Jonathan Wright, Innes C CuthillAbstract:Abstract In species with biparental care, the evolutionarily stable strategy for investment in the Brood depends on the value of the Brood to the parents and on each partner's contribution. Any shortfall by one parent should be partially compensated for by the other parent, with the magnitude of this ’response’ depending on the value of the Brood. Small weights were attached to one member of European starling, Sturnus vulgaris, pairs, to introduce biases in the division of labour whilst retaining a biparental system. Manipulation of both Brood Size and a partner's work rate demonstrated that: (1) each sex compensated for a partner's experimentally reduced work rate; (2) the magnitude of response depended on the manipulated Brood Size; (3) weighted birds and their partners delivered more small invertebrates than did controls; and (4) male and female effort was asymmetric with respect to Brood Size. These results accord with several general predictions of game theoretical models, but specific departures from expectation are discussed.
Juan Jose Sanz - One of the best experts on this subject based on the ideXlab platform.
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flexibility in the foraging behavior of blue tits in response to short term manipulations of Brood Size
Ethology, 2010Co-Authors: Vicente Garcianavas, Juan Jose SanzAbstract:Previous work suggests that short-term changes in feeding rate are usually produced by the parent-offspring interaction. However, few studies have properly tested this assumption. In this study, we attempt to explore the short-term consequences of daily (within-pair) Brood Size manipulations (reduced, original, and enlarged) on feeding behavior (provisioning rates, prey Size, and prey type) of Mediterranean blue tits Cyanistes caeruleus. Total provisioning rates were lowest when Broods were reduced in Size and greatest when Broods were enlarged. Mean prey Size was also affected by the Brood Size changes: parents tended to bring larger prey when confronted with low Brood demand reinforcing the view that a trade-off exists between minimizing foraging time and maximizing food quantity. Such differences in feeding frequencies and the load Sizes delivered may be explained by changes in the parents’ foraging tactic. Increase of Brood Size compelled parents to work harder and be less selective in prey choice; we found that stressed birds with a high level of feeding responsibility (hungry nestlings) opted to concentrate on more readily available food items (Tortricids). On the other hand, their immediate reaction when faced with a low level of feeding responsibility was to decrease this prey type in the diet, so that the percentage of other preys (Noctuids) in the diet increased. There was no intersexual difference in the way in which parents responded to the manipulation. In sum, our results revealed a flexibility in foraging strategies of blue tits to cope with changing scenarios, which supports the idea that provisioning behavior is largely governed by nestling demand.
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strong evidence for selection for larger Brood Size in a great tit population
Behavioral Ecology, 2004Co-Authors: Joost M Tinbergen, Juan Jose SanzAbstract:We measured the selection pressure on Brood Size in a recently established population of great tits (Parus major L.) in the northern Netherlands by manipulating Brood Size in three years (1995: n e 51, 1997: n e 66, 1998: n e 51), and we estimated fitness consequences in terms of local survival of both offspring and parents. Enlarged Broods had highest fitness; the offspring fitness component was positively affected by manipulation and the parental fitness component was unaffected. Parental survival and the probability that parents produced a second clutch were not affected by the treatment. However, parents that had raised enlarged Broods produced their second clutch later in the season. Clutch Size, Brood Size, and laying date of birds recaptured in the next breeding season were largely independent of the treatment. We conclude that there is strong evidence for selection for larger Brood Size and reject the individual optimization hypothesis for this population because the number of young in the nest predicts fitness independently of the manipulation history. Copyright 2004.
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energy expenditure nestling age and Brood Size an experimental study of parental behavior in the great tit parus major
Behavioral Ecology, 1999Co-Authors: Juan Jose Sanz, Joost M TinbergenAbstract:A Brood manipulation experiment on great tits Parus major was performed to study the effects of nestling age and Brood Size on parental care and offspring survival. Daily energy expenditure (DEE) of females feeding nestlings of 6 and 12 days of age was measured using the doubly-labeled water technique. Females adjusted their Brooding behavior to the age of the young. The data are consistent with the idea that Brooding behavior was determined primarily by the thermoregulatory requirements of the Brood. Female DEE did not differ with nestling age; when differences in body mass were controlled for, it was lower during the Brooding period than later. In enlarged Broods, both parents showed significantly higher rates of food provisioning to the Brood. Female DEE was affected by Brood Size manipulation, and it did not level off with Brood Size. There was no significant effect of nestling age on the relation between DEE and manipulation. Birds were able to raise a larger Brood than the natural Brood Size, although larger Broods suffered from increased nestling mortality rates during the peak demand period of the nestlings. Offspring condition at fledging was negatively affected by Brood Size manipulation, but recruitment rate per Brood was positively related to Brood Size, suggesting that the optimal Brood Size exceeds the natural Brood Size in this population. Key words: Brood Size manipulation, doubly-labeled water technique, energy expenditure, great tits, parental care, Parus major. [Behav Ecol 10:598‐606 (1999)]
