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1.

001-es BibID:BIBFORM022957
Első szerző:Barta Zoltán (biológus, zoológus)
Cím:Sexual Conflict about Parental Care : the Role of Reserves / Zoltán Barta, Alasdair I. Houston, John M. McNamara, Tamás Székely
Dátum:2002
Megjegyzések:Parental care often increases the survival of offspring, but it is costly to parents. Because of this trade-off, a sexual conflict over care arises. The solution to this conflict depends on the interactions between the male and female parents, the behavior of other animals in the population, and the individual differences within a sex. We take an integrated approach and develop a state-dependent dynamic game model of parental care. The model investigates a single breeding season in which the animals can breed several times. Each parent's decision about whether to care for the brood or desert depends on its own energy reserves, its mate's reserves, and the time in the season. We develop a fully consistent solution in which the behavior of an animal is the best given the behavior of its mate and of all other animals in the population. The model predicts that females may strategically reduce their own reserves so as to "force" their mate to provide care. We investigate how the energy costs of caring and searching for a mate, values of care (how the probability of offspring survival depends on the pattern of care), and population sex ratio influence the pattern of care over the breeding season.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
sexual conflict
parental care
offspring desertion
dynamic game
reserves
body mass regulation
Megjelenés:American Naturalist. - 159 : 6 (2002), p. 687-705. -
További szerzők:Houston, Alasdair I. McNamara, John M. Székely Tamás (1959-) (biológus)
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2.

001-es BibID:BIBFORM021579
Első szerző:Barta Zoltán (biológus, zoológus)
Cím:Annual routines of non-migratory birds : optimal moult strategies / Zoltán Barta, Alasdair I. Houston, John M. McNamara, Robert K. Welham, Anders Hedenström, Thomas P. Weber, Orsolya Feró
Dátum:2006
ISSN:0030-1299
Megjegyzések:In a periodically changing environment it is important for animals to properly time the major events of their life in order to maximise their lifetime fitness. For a non-migratory bird the timing of breeding and moult are thought to be the most crucial. We develop a state-dependent optimal annual routine model that incorporates explicit density dependence in the food supply. In the model the birds' decisions depend on the time of year, their energy reserves, breeding status, experience, and the quality of two types of feathers (outer and inner primaries). Our model predicts that, under a seasonal environment, feathers with large effects on flight ability, higher abrasion rate and lower energetic cost of moult should be moulted closer to the winter (i.e. later) than those with the opposite attributes. Therefore, we argue that the sequence of moult may be an adaptive response to the problem of optimal timing of moult of differing feathers within the same feather tract. The model also predicts that environmental seasonality greatly affects optimal annual routines. Under high seasonality birds breed first then immediately moult, whereas under low seasonality an alternation occurs between breeding and moulting some of the feathers in one year and having a complete moult but no breeding in the other year. Increasing food abundance has a similar effect.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
Megjelenés:Oikos. - 112 (2006), p. 580-593. -
További szerzők:Houston, Alasdair I. McNamara, John M. Welham, Robert K. Hedenström, Anders Weber, Thomas P. Feró Orsolya
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3.

001-es BibID:BIBFORM018796
Első szerző:Barta Zoltán (biológus, zoológus)
Cím:Optimal moult strategies in migratory birds / Zoltán Barta, John M. McNamara, Alasdair I. Houston, Thomas P. Weber, Anders Hedenström, Orsolya Feró
Dátum:2008
Megjegyzések:Avian migration, which involves billions of birds flying vast distances, is known to influence all aspects of avian life. Here we investigate how birds fit moult into an annual cycle determined by the need to migrate. Large variation exists in moulting patterns in relation to migration: for instance, moult can occur after breeding in the summer or after arrival in the wintering quarters. Here we use an optimal annual routine model to investigate why this variation exists. The modelled bird's decisions depend on the time of year, its energy reserves, breeding status, experience, flight feather quality and location. Our results suggest that the temporal and spatial variations in food are an important influence on a migratory bird's annual cycle. Summer moult occurs when food has a high peak on the breeding site in the summer, but it is less seasonal elsewhere. Winter moult occurs if there is a short period of high food availability in summer and a strong winter peak at different locations (i.e. the food is very seasonal but in opposite phase on these areas). This finding might explain why only long-distance migrants have a winter moult.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
optimal annual routines
moult
migration
birds
state-dependent dynamic models
dynamic programming
Megjelenés:Philosophical Transactions Of The Royal Society of London, Series B. - 363 : 1490 (2008), p. 211-230. -
További szerzők:McNamara, John M. Houston, Alasdair I. Weber, Thomas P. Hedenström, Anders Feró Orsolya
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4.

001-es BibID:BIBFORM018795
Első szerző:Feró Orsolya
Cím:Optimal annual routines : New tools for conservation biology / Orsolya Feró, Philip A. Stephens, Zoltán Barta, John M. McNamara, Alasdair I. Houston
Dátum:2008
Megjegyzések:Many applied problems in ecology and conservation require prediction, and population models are important tools for that purpose. Formerly, the majority of predictive population models were based on matrix models. As the limitations of classical matrix models have become clearer, the use of individual-based models has increased. These models use behavioral rules imposed at the level of the individual to establish the emergent consequences of those rules at the population level. Individual behaviors in such models use an array of different rule types, from empirically derived probabilities to long-term fitness considerations. There has been surprisingly little discussion of the strengths and weaknesses of these different rule types. Here, we consider different strategies for modeling individual behaviors, together with some problems associated with individual-based models. We propose a novel approach based on modeling optimal annual routines. Annual routines allow individual behaviors to be predicted over a whole annual cycle within the context of long-term fitness considerations. Temporal trade-offs between different behaviors are automatically included in annual routine models, overcoming some of the primary limitations of other individual-based models. Furthermore, as well as population predictions, individual behaviors and indices of condition are emergent features of annual routine models. We show that these can be more sensitive to environmental change than population size, offering alternative, repeatable metrics for monitoring population status. Annual routine models provide no panacea for the problems of data limitations in predictive population modeling. However, as a result of their ability to deal with life-history trade-offs, as well as their potential for relatively rapid and accurate validation and parameterization, we suggest that annual routine models have strong potential for predictive population modeling in applied conservation settings.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
environmental change
habitat degradation
individual-based models
migration
molt
optimality
population dynamics
Megjelenés:Ecological Applications. - 18 : 6 (2008), p. 1563-1577. -
További szerzők:Stephens, Philip A. Barta Zoltán (1967-) (biológus, zoológus) McNamara, John M. Houston, Alasdair I.
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5.

001-es BibID:BIBFORM022923
Első szerző:Houston, Alasdair I.
Cím:The effect of foraging parameters on the probability that a dive is successful / Alasdair I. Houston, John M. McNamara, Jon E. Heron, Zoltán Barta
Dátum:2003
ISSN:0962-8452
Megjegyzések:In this paper, we investigate the foraging decisions of an animal that dives to obtain its food. It might seem reasonable to use the probability that the diver is successful in any dive as an indicator of habitat quality. We use a dynamic model of optimal prey choice to show that this interpretation of diving success is not generally valid. In particular, we show that diving success is not directly proportional to the overall rate of gain that can be achieved in an environment. Furthermore, some environmental factors can have a non-monotonic effect on the probability of success. For example, as the travel time to the foraging area increases, the probability of success may first increase and then decrease. We point out that the same conclusions are likely to apply in the context of mate choice, i.e. the probability of getting a mate may not be an indicator of the quality of the environment in terms of reproductive success
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
diving
optimal choice
probability of success
indicator
Megjelenés:Proceedings of the Royal Society. Series B. Biological sciences. - 270 : 1532 (2003), p. 2451-2455. -
További szerzők:McNamara, John M. Heron, Jon E. Barta Zoltán (1967-) (biológus, zoológus)
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6.

001-es BibID:BIBFORM018805
Első szerző:Houston, Alasdair I.
Cím:The effect of energy reserves and food availability on optimal immune defence / Alasdair I. Houston, John M. McNamara, Zoltán Barta, Kirk C. Klasing
Dátum:2007
ISSN:0962-8452
Megjegyzések:In order to avoid both starvation and disease, animals must allocate resources between energy reserves and immune defence. We investigate the optimal allocation. We find that animals with low reserves choose to allocate less to defence than animals with higher reserves because when reserves are low it is more important to increase reserves to reduce the risk of starvation in the future. In general, investment in immune defence increases monotonically with energy reserves. An exception is when the animal can reduce its probability of death from disease by reducing its foraging rate. In this case, allocation to immune defence can peak at intermediate reserves. When food changes over time, the optimal response depends on the frequency of changes. If the environment is relatively stable, animals forage most intensively when the food is scarce and invest more in immune defence when the food is abundant than when it is scarce. If the environment changes quickly, animals forage at low intensity when the food is scarce, but at high intensity when the food is abundant. As the rate of environmental change increases, immune defence becomes less dependent on food availability. We show that the strength of selection on reserve-dependent immune defence depends on how foraging intensity and immune defence determine the probability of death from disease.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
immunity; state-dependence; dynamic programming; energy reserves
Megjelenés:Proceedings of the Royal Society. Series B. Biological sciences. - 274 : 1627 (2007), p. 2835-2842. -
További szerzők:McNamara, John M. Klasing, Kirk C. Barta Zoltán (1967-) (biológus, zoológus)
Pályázati támogatás:OTKA
NF 61143
OTKA
T046661
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7.

001-es BibID:BIBFORM022924
Első szerző:McNamara, John M.
Cím:Should young ever be better off with one parent than with two? / John M. McNamara, Alasdair I. Houston, Zoltán Barta, José-Luis Osorno
Dátum:2003
Megjegyzések:We analyze models of parental care, providing the first systematic comparison of the care given to young by one parent versus by two parents. In the Houston-Davies model of care, young always do better with two parents rather than with one parent. When one parent decides about its level of care before the other, then the young may do better with one parent when the costs of care for the parents are asymmetric. When the level of parental effort is reached by negotiation, there are cases in which young do better with one parent, even when costs are symmetric. The analysis suggests empirical ways to differentiate between different response rules
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
game theory
mate removal
negotiation
parental effort
Megjelenés:Behavioral Ecology. - 14 : 3 (2003), p. 301-310. -
További szerzők:Houston, Alasdair I. Barta Zoltán (1967-) (biológus, zoológus) Osorno, José-Luis
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8.

001-es BibID:BIBFORM022869
Első szerző:McNamara, John M.
Cím:Variation in behaviour promotes cooperation in the Prisoner's Dilemma game / John M. McNamara, Zoltan Barta, Alasdair I. Houston
Dátum:2004
ISSN:0028-0836
Tárgyszavak:Természettudományok Biológiai tudományok levél
Megjelenés:Nature. - 428 : 6984 (2004), p. 745-748. -
További szerzők:Barta Zoltán (1967-) (biológus, zoológus) Houston, Alasdair I.
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9.

001-es BibID:BIBFORM022834
Első szerző:McNamara, John M.
Cím:A theoretical investigation of the effect of predators on foraging behaviour and energy reserves / John M. McNamara, Zoltan Barta, Alasdair I. Houston, Philip Race
Dátum:2005
Megjegyzések:Data show that when small birds are exposed to a model of a predator, their body mass may either increase or decrease. Although attempts have been made to explain the data using previous models, these models are based on a constant level of predation and hence are not appropriate for making predictions about the response of a bird to the sight of a predator. We have developed a novel model that includes encounters between a bird and potential predators. We show that, depending on the biology of the predator, optimal body mass may either increase or decrease. The model also makes predictions about the foraging behaviour of the bird after it has seen a predator.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
energy reserves
starvation
predation
foraging
minimising mortality
Megjelenés:Proceedings of the Royal Society. Series B. Biological sciences. - 272 : 1566 (2005), p. 929-934. -
További szerzők:Barta Zoltán (1967-) (biológus, zoológus) Houston, Alasdair I. Race, Philip
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10.

001-es BibID:BIBFORM018788
Első szerző:McNamara, John M.
Cím:The optimal coyness game / John M. McNamara, Lutz Fromhage, Zoltan Barta, Alasdair I. Houston
Dátum:2009
ISSN:0962-8452
Megjegyzések:In many animal species, females will benefit if they can secure their mate's help in raising their young. It has been suggested that they can achieve this by being coy (i.e. reluctant to mate) when courted, because this gives them time to assess a prospective mate's helpfulness and hence allows them to reject non-helpful males. According to this view, coyness should (i) reflect a trade-off between information gain and time lost on the part of the female, and (ii) be subject to an evolutionary feedback between optimal female coyness and male helping behaviour. Previous theory has considered each of these aspects in isolation. By contrast, here we present a comprehensive game theory model of this situation, leading to qualitatively new insights. We predict that a high degree of coyness should be associated with a high encounter rate during mate search, with an intermediate rate of information gain during mate inspection and with an intermediate dependence of reproduction on male help. Strongly biased sex ratios, however, preclude coyness. Due to the mutual feedback between coyness and helpfulness in our model, alternatively stable evolutionary outcomes (with or without coyness) are possible under broad conditions. We also discuss alternative interpretations of coyness.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
'battle of the sexes'
mate choice
courtship
sexual selection
parental care
game theory
Megjelenés:Proceedings of the Royal Society. Series B. Biological sciences. - 276 : 1658 (2009), p. 953-960. -
További szerzők:Fromhage, Lutz Barta Zoltán (1967-) (biológus, zoológus) Houston, Alasdair I.
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11.

001-es BibID:BIBFORM018790
Első szerző:McNamara, John M.
Cím:A Theoretical Investigation of the Effect of Latitude on Avian Life Histories / John M. McNamara, Zoltán Barta, Martin Wikelski, Alasdair I. Houston
Dátum:2008
Megjegyzések:Tropical birds lay smaller clutches than birds breeding in temperate regions and care for their young for longer. We develop a model in which birds choose when and how often to breed and their clutch size, depending on their foraging ability and the food availability. The food supply is density dependent. Seasonal environments necessarily have a high food peak in summer; in winter, food levels drop below those characteristic of constant environments. A bird that cannot balance its energy needs during a week dies of starvation. If adult predation is negligible, birds in low seasonal environments are constrained by low food during breeding seasons, whereas birds in high seasonal environments die during the winter. Low food seasonality selects for small clutch sizes, long parental care times, greater age at first breeding, and high juvenile survival. The inclusion of adult predation has no major effect on any life-history variables. However, increased nest predation reduces clutch size. The same trends with seasonality are also found in a version of the model that includes a condition variable. Our results show that seasonal changes in food supply are sufficient to explain the observed trends in clutch size, care times, and age at first breeding.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
annual routine, clutch size, energy balance, parental care.
Megjelenés:The American Naturalist. - 172 : 3 (2008), p. 331-345. -
További szerzők:Barta Zoltán (1967-) (biológus, zoológus) Wikelski, Martin Houston, Alasdair I.
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12.

001-es BibID:BIBFORM018772
Első szerző:McNamara, John M.
Cím:Deterioration, death and the evolution of reproductive restraint in late life / John M. McNamara, Alasdair I. Houston, Zoltan Barta, Alexander Scheuerlein, Lutz Fromhage
Dátum:2009
ISSN:0962-8452
Megjegyzések:Explaining why organisms schedule reproduction over their lifetimes in the various ways that they do is an enduring challenge in biology. An influential theoretical prediction states that organisms should increasingly invest in reproduction as they approach the end of their life. An apparent mismatch of empirical data with this prediction has been attributed to age-related constraints on the ability to reproduce. Here we present a general framework for the evolution of age-related reproductive trajectories. Instead of characterizing an organism by its age, we characterize it by its physiological condition. We develop a common currency that if maximized at each time guarantees the whole life history is optimal. This currency integrates reproduction, mortality and changes in condition. We predict that under broad conditions it will be optimal for organisms to invest less in reproduction as they age, thus challenging traditional interpretations of age-related traits and renewing debate about the extent to which observed life histories are shaped by constraint versus adaptation. Our analysis gives a striking illustration of the differences between an age-based and a condition-based approach to life-history theory. It also provides a unified account of not only standard life-history models but of related models involving the allocation of limited resources.
Tárgyszavak:Természettudományok Biológiai tudományok idegen nyelvű folyóiratközlemény külföldi lapban
life history
reproduction
terminal investment
ageing
senescence
Megjelenés:Proceedings of the Royal Society. Series B. Biological sciences. - 276 : 1675 (2009), p. 4061-4066. -
További szerzők:Houston, Alasdair I. Barta Zoltán (1967-) (biológus, zoológus) Scheuerlein, Alexander Fromhage, Lutz
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