Dr. Bán Miklós
MTA-DE "Lendület" Viselkedésökológiai Csoport
Debreceni Egyetem, Evolúciós Állattani Tsz.
4010, Debrecen Egyetem tér1.
Tel: +36 52 512-900 / 62356
Kakukk - gazda koevolúció, evolúciós versenyfutás
Fészkelő madarak zavart környezetben - Almáskert projekt
Ökológiai adatbázisok és térképi megjelenítés OpenBioMaps
- Foreign egg retention by avian hosts in repeated brood parasitism: why do rejecters accept? (2014)
Csaba Moskát & Márk E. Hauber & Zoltán Elek & Moniek Gommers & Miklós Bán & Frank Groenewoud &
Tom S. L. Versluijs & Christiaan W. A. Hoetz & Jan Komdeur
Behavioral Ecology and Sociobiology
Foreign egg retention by avian hosts in repeated brood parasitism: why do rejecters accept?
Great reed warblers (Acrocephalus arundinaceus) are frequently parasitized by egg-mimetic common cuckoos (Cuculus canorus) in Hungary, and these hosts reject about a third of parasitic eggs. The timing of parasitism is important, in that the probability of rejection decreases with advancing breeding stages in this host. Also, egg rejection is more common when a clutch is parasitized by a single foreign egg, compared to parasitism by multiple eggs. We repeatedly parasitized great reed warbler clutches with moderately mimetic foreign eggs, either with (1) one foreign egg (single parasitism) and, after 3 days, by all foreign eggs (multiple parasitism), or (2) all foreign eggs and, 3 days later, by only one foreign egg. Hosts ejected 26–53 % of the experimental parasitic eggs in the first stage of the repeated parasitism, but
almost all eggs were accepted in the second stage, irrespective of whether the clutch was singly or multiply parasitized. Video-taping of the behavioural responses of hosts to experimental parasitism revealed no evidence for sensory constraints on foreign-egg recognition, because hosts recognized
and pecked the parasitic eggs as frequently in the second stage of repeated parasitism, as they did in the first stage. We suggest that the relative timing of parasitism (laying vs. incubation stage), rather than learning to accept earlier-laid foreign eggs, results in higher acceptance rates of cuckoo eggs in
repeated parasitism, because there is decreasing natural cuckoo parasitism on this host species and, hence, less need for antiparasitic defences, with the advancing stages of breeding.
Behavioral Ecology and Sociobiology 2014: Letöltés
- How to Spot a Stranger’s Egg? A Mimicry-Specific Discordancy Effect in the Recognition of Parasitic Eggs (2014)
Moskát C, Zöllei A, Bán M, Elek Z, Tong L, Geltsch N, Hauber M
How to Spot a Stranger’s Egg? A Mimicry-Specific Discordancy Effect in the Recognition of Parasitic Eggs
Egg discrimination by hosts is an antiparasitic defence to reject foreign eggs from the nest. Even when mimetic, the presence of brood parasitic egg(s) typically alters the overall similarity of all eggs in a clutch, producing a discordant clutch compared to more homogenous clutches of composed only
of hosts’ own eggs. In multiple parasitism, the more foreign eggs are laid in the nest, the more heterogeneous the overall clutch appears. Perceptual filters and recognition templates cannot explain the known pattern of lower rejection rates of foreign eggs in multiple vs. single parasitism. We
therefore assessed the role of clutch homogeneity and manipulated the colour of one or more eggs in the clutches of great reed warbler (Acrocephalus arundinaceus) hosts of common cuckoos (Cuculus canorus). Varying the colours of both the majority and the minority eggs caused predictable shifts in the rejection of the focal egg(s), and ejection rates of the minority egg colour consistently increased but only when it belonged to a more mimetic egg colour, relative to the less mimetic colour of majority eggs.
The results imply that in addition to sensory filters, and template-based cognitive decision rules, discordancy-based rejection is affected by the overall clutch appearance and interacts with specific colours varying in the extent of mimicry, to contribute to the recognition decisions of hosts to reject parasitic eggs.
Ethology 2014: Letöltés
- Simultaneous viewing of own and parasitic eggs is not required for egg rejection by a cuckoo host (2013)
Miklós Bán, Csaba Moskát, Zoltán Barta, and Márk E. Hauber
Simultaneous viewing of own and parasitic eggs is not required for egg rejection by a cuckoo host
Many hosts have evolved diverse cognitive mechanisms to recognize and reduce the cost of social parasitism. For example, great reed warblers Acrocephalus arundinaceus can accurately reject closely mimetic eggs of brood parasitic common cuckoos Cuculus canorus. Yet, these same hosts are less effective at identifying and rejecting parasitism when the clutch is parasitized by multiple cuckoo eggs, suggesting a role for discordancy (the rejection of the egg type in the minority of the clutch) and/or online self-referent phenotype matching (the simultaneous viewing of cuckoo and own eggs in the nest) to reject foreign eggs. We tested whether the presence of host’s own eggs is required for the discrimination of foreign eggs by dyeing hosts’ own eggs with one of several colors so that clutches contained (a) 1 dyed and 4 unmanipulated eggs, (b) 3 dyed and 2 unmanipulated eggs, or 5 eggs dyed either (c1) differently or (c2) similarly. Rejection rates of dyed eggs varied widely between different colors and were highest in treatment (a), with 1 dyed egg, compared with treatments with the majority (b) or all (c1 and c2) dyed eggs. However, relative rejection rates of dyed eggs were also consistent among specific colors across treatments, including (c1) and (c2), where no unmanipulated own eggs were available for viewing and irrespective of whether eggs were dyed all different colors (c1) or the same colors (c2). We conclude that these hosts can rely on comparisons of foreign egg colors against an internal recognition template of acceptable (own) egg phenotypes.
Behavioral Ecology 2013: Letöltés
- Competition with a host nestling for parental provisioning imposes recoverable costs on parasitic cuckoo chick’s growth (2012)
Nikoletta Geltsch, Márk E. Hauber, Michael G. Anderson, Miklós Bán, Csaba Moskát
Competition with a host nestling for parental provisioning imposes recoverable costs on parasitic cuckoo chick’s growth
Chicks of the brood parasitic common cuckoo (Cuculus canorus) typically monopolize host parental care by evicting all eggs and nestmates from the nest. To assess the benefits of parasitic eviction behaviour throughout the full nestling period, we generated mixed broods of one cuckoo and one great reed war- bler (Acrocephalus arundinaceus) to study how hosts divide care between own and parasitic young. We also recorded parental provisioning behaviour at nests of singleton host nestlings or singleton cuckoo chicks. Host parents fed the three types of broods with similar-sized food items. The mass of the cuckoo chicks was significantly reduced in mixed broods relative to singleton cuckoos. Yet, after the host chick fledged from mixed broods, at about 10–12 days, cuckoo chicks in mixed broods grew faster and appeared to have compensated for the growth costs of prior cohabitation by fledging at similar weights and ages compared to singleton cuckoo chicks. These results are contrary to suggestions that chick competition in mixed broods of cuckoos and hosts causes an irrecoverable cost for the develop- ing brood parasite. Flexibility in cuckoo’ growth dynamics may provide a general benefit to ecological uncertainty regarding the realized successes, failures, and costs of nestmate eviction strategies of brood parasites.
Behavioural Processes 2012: Letöltés
- Cuckoo parasitism on two closely-related Acrocephalus warblers in distant areas: a case of parallel coevolution? (2012)
Csaba Moskát, Fugo Takasu, A. Roman Muñoz, Hiroshi Nakamura, Miklós Bán, Zoltán Barta
Cuckoo parasitism on two closely-related Acrocephalus warblers in distant areas: a case of parallel coevolution?
Common Cuckoos (Cuculus canorus) parasitize nests of small passerines. The Cuckoo chicks cause the death of their nest-mates when evicting eggs or nestlings from the nests; consequently, hosts suffer from a high loss of reproduction. Host adaptations against parasitism, e.g., by egg discrimination behavior, and cuckoo counter-adaptations to hosts, e.g., by mimetic eggs, are often regarded as a result of the arms race between the two interacting species. In Hungary Great Reed Warblers (Acrocephalus arundinaceus) are the main hosts of cuckoos, suffering from heavy parasitism (ca. 40–65%). The Oriental Reed Warbler (A. orientalis), formerly a subspecies of the Great Reed Warbler (A. a. orientalis), is also a highly parasitized host in Japan (25–40%). We compared main characteristics of Cuckoo parasitism in these two distant areas from the Western and Eastern Palearctic by comparing cuckoo egg mimicry. We measured color characteristics of host and parasitic eggs by spectrophotometer. Visual modeling revealed lower chromatic distances between Cuckoo and host eggs in Hungary than in Japan, but high variation both in host and Cuckoo eggs may cause matching problems in Hungary. Achromatic (brightness) difference between host and Cuckoo eggs were lower in Japan than in Hungary, and it proved to be the most important factor affecting egg rejection. Hosts rejected Cuckoo eggs at similar frequencies (37% and 35% in Hungary and Japan, respectively). Host adaptation, i.e., egg rejection behavior, seems to be preceding Cuckoo counteradaptations to hosts in Japan. We suggest that the Cuckoo-Great/Oriental Reed Warbler relationships developed in alternative ways in Japan and Hungary, and they represent different stages of their arms race.
Chienese Birds 2012: Letöltés
- Variation in plasma oxidative status and testosterone level in relation to egg-eviction effort and age of brood-parasitic common cuckoo nestlings (2012)
Rita Hargitai, David Costantini, Csaba Moskát, Miklós Bán, Jaime Muriel, and Mark E. Hauber
Variation in plasma oxidative status and testosterone level in relation to egg-eviction effort and age of brood-parasitic common cuckoo nestlings
To avoid competition for parental care, brood-parasitic Common Cuckoo (Cuculus canorus)
nestlings evict all of the host’s eggs and nestlings within a few days after hatching. Little is known about the
physiological effects of eviction behavior on the cuckoo nestling’s oxidative balance or about age-related varia-
tion in plasma oxidative status and testosterone level of developing birds. We examined whether the cuckoo
nestling’s plasma oxidative status was related to prior effort in eviction and quantified variation in the level of
reactive oxygen metabolites, of nonenzymatic antioxidant capacity, and of testosterone concentration in plasma
at various phases of the cuckoo’s development. Levels of both reactive oxygen metabolites and antioxidant
capacity were greater in older than in younger nestlings, suggesting that younger nestlings effectively counter-
balance their increased production of free radicals, whereas, near fledging, levels of reactive oxygen metabo-
lites increase despite improved antioxidant capacity. Possibly, overall energy expenditure increases with age
and elevates the production of reactive oxygen species to a rate higher than what the antioxidant system could
eliminate. Plasma testosterone level was the highest at nestlings’ intermediate phase of growth. High levels of
testosterone may be required during the period of fastest growth, and when the growth rate levels off near fledg-
ing, testosterone levels may also decline. Cuckoo chicks that evicted more host eggs from steeper nests had
higher plasma levels of reactive oxygen metabolites shortly after the eviction period, suggesting that eviction is
costly in terms of an increased level of oxidative stress.
The Condor 2012: Letöltés
- The analysis of common cuckoo’s egg shape in relation to its hosts’ in two geographically distant areas (2011)
M. Bán, Z. Barta, A. R. Munoz, F. Takasu, H. Nakamura & C. Moskát
Journal of Zoology
The analysis of common cuckoo’s egg shape in relation to its hosts’ in two geographically distant areas
Evolutionary adaptations are required by common cuckoos Cuculus canorus to match host eggs. Hosts may discriminate against alien eggs; hence, accurate matching of the parasite egg to the hosts’ is essential. Egg shape is the least-studied component of egg mimicry, and it may also have other functions: an optimal egg shape is necessary for effective incubation. For this reason, cuckoo eggs may show a wide range of variations in shape to a set of host species. Here, we compare cuckoo and host eggs by using egg shape parameters in two distant areas: from the nests of great reed warblers Acrocephalus arundinaceus, robins Erithacus rubecula and marsh warblers Acrocephalus palustris in Hungary, and oriental reed warblers Acrocephalus orientalis, bull-headed shrikes Lanius bucephalus and black-faced buntings Emberiza spodocephala from Japan. Our results suggest the lack of evolutionary adaptation of different cuckoo gentes to their corresponding hosts in terms of egg shape. However, our analyses revealed that cuckoo eggs showed a geographical difference in egg shape.
Journal of Zoology 2011: Letöltés
- Post-ejection nest-desertion of common cuckoo hosts: a second defense mechanism or avoiding reduced reproductive success? (2010)
Csaba Moskát, Erik C. Rosendaal, Myra Boers, Anikó Zölei, Miklós Bán, Jan Komdeur
Behavioral Ecology and Sociobiology
Post-ejection nest-desertion of common cuckoo hosts: a second defense mechanism or avoiding reduced reproductive success?
Hosts of the common cuckoo (Cuculus canorus), an avian brood parasite, develop antiparasite defense mechanisms to increase their reproductive success. Ejection of the parasite egg and desertion of the parasitized nest are the most typical adaptations in response to brood parasit- ism, but nest desertion may also occur in response to partial clutch reduction, independently from parasitism. Some great reed warblers (Acrocephalus arundinaceus) showed both mechanisms in the same incidence of cuckoo parasitism: in 18% of successful ejections of the parasite eggs, they deserted their nests. We studied if such cases of post-ejection nest-desertion are caused by brood parasitism or reduced clutch value. We experimentally parasitized clutches consisting of five or three host eggs with two painted conspecific eggs to mimic parasitic eggs, as multiple parasitism is frequent in the area. Although hosts ejected these parasitic eggs in both clutch categories (100% and 67% for the larger and smaller inital clutch sizes, respectively), we found that after manipulation, post- ejection nest-desertion frequently occurred at small (3-egg) clutches (40%), but rarely at large (5-egg) clutches (17%). The same phenomenon also occurred when unparasitized 3-egg clutches were reduced by two eggs, but not when 5-egg clutches were reduced in the same way. A logistic regression model revealed that only initial clutch size affected nest desertion of parasitized nests in our experiments. Therefore, we conclude that post-ejection nest-desertion is not a second antiparasite mechanism, which might serve as a redundant antiparasite defense, but a reaction to typically small and further decreased clutch size.
Behavioral Ecology and Sociobiology 2010: Letöltés
- Eggshell characteristics and yolk composition in the common cuckoo Cuculus canorus: are they adapted to brood parasitism? (2010)
Rita Hargitai, Csaba Moskát, Miklós Bán, Diego Gil, Isabel Lopez-Rull and Emese Solymos
Journal of Avian Biology
Eggshell characteristics and yolk composition in the common cuckoo Cuculus canorus: are they adapted to brood parasitism?
The developmental rate of cuckoo embryos and their hatching size is greater than that of host species, which may require more nutrient resources in the egg and more intensive gas exchange during development. In the present study, we compared various egg characteristics of a brood parasite, the common cuckoo Cuculus canorus, and its frequent host, the great reed warbler Acrocephalus arundinaceus. As maternally-derived testosterone is known to enhance growth rate of embryos and hatchlings, cuckoo eggs are expected to contain higher concentration of testosterone than host eggs. In addition, we expected higher concentration of antioxidants in cuckoo eggs to protect embryos from oxidative stress associated with accelerated growth. Our results showed that cuckoo eggs had thicker shells and higher pore density than great reed warbler eggs. Yolk was significantly heavier in cuckoo eggs and contained higher concentrations of carotenoids and vitamin E, however, yolk androgen and immunoglobulin concentrations were lower in cuckoo eggs as compared to great reed warbler eggs. We also examined whether eggshell colour was associated to egg quality, and detected a positive association between blue-green chroma and yolk antioxidant concentration in both species, suggesting that eggshell colour reflects the antioxidant investment of the female into the eggs. Our results suggest that cuckoo females increase the size, growth rate and competitive ability of their young by providing them with more nutrients and more dietary antioxidants for embryonic development, and not through elevated yolk testosterone or antibody levels. In addition, increased porosity of cuckoo eggshells may allow embryos to develop more rapidly because of a greater capacity of gas exchange.
Journal of Avian Biology 2010: Letöltés
- Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites (2010)
Csaba Moskát, Miklós Bán, Tamás Székely, Jan Komdeur, Rim W. G. Lucassen, Lotte A. van Boheemen and Márk E. Hauber
Journal of Experimental Biology
Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites
Many avian hosts have evolved antiparasite defence mechanisms, including egg rejection, to reduce the costs of brood parasitism. The two main alternative cognitive mechanisms of egg discrimination are thought to be based on the perceived discordancy of eggs in a clutch or the use of recognition templates by hosts. Our experiments reveal that the great reed warbler (Acrocephalus arundinaceus), a host of the common cuckoo (Cuculus canorus), relies on both mechanisms. In support of the discordancy mechanism, hosts rejected their own eggs (13%) and manipulated (‘parasitic’) eggs (27%) above control levels in experiments when manipulated eggs were in the majority but when clutches also included a minority of own eggs. Hosts that had the chance to observe the manipulated eggs daily just after laying did not show stronger rejection of manipulated eggs than when the eggs were manipulated at clutch completion. When clutches contained only manipulated eggs, in 33% of the nests hosts showed rejection, also supporting a mechanism of template-based egg discrimination. Rejection using a recognition template might be more advantageous because discordancy-based egg discrimination is increasingly error prone with higher rates of multiple parasitism.
Journal of Experimental Biology 2010: Letöltés
- Internal incubation and early hatching in brood parasitic birds (2010)
T. R. Birkhead, N. Hemmings, C. N. Spottiswoode, O. Mikulica, C. Moskát, M. Bán and K. Schulze-Hagen
Proceedings of the Royal Society, Biological Sciences
Internal incubation and early hatching in brood parasitic birds
The offspring of brood parasitic birds benefit from hatching earlier than host young. A proposed but little- known strategy to achieve this is ‘internal incubation’, by retaining the egg in the oviduct for an additional 24 h. To test this, we quantified the stage of embryo development at laying in four brood parasitic birds (European cuckoo, Cuculus canorus
; African cuckoo, Cuculus gularis
; greater honeyguide, Indicator indicator
; and the cuckoo finch, Anomalospiza imberbis
). For the two cuckoos and the honeyguide, all of which lay at 48 h intervals, embryos were at a relatively advanced stage at laying; but for the cuckoo finch (laying interval: 24 h) embryo stage was similar to all other passerines laying at 24 h intervals. The stage of embryo development in the two cuckoos and honeyguide was similar to that of a non-parasitic species that lay at an interval of 44 – 46 h, but also to the eggs of the zebra finch Taeniopygia guttata
incubated artificially at body temperature immediately after laying, for a further 24 h. Comparison with the zebra finch shows that internal incubation in the two cuckoos and honeyguide advances hatching by 31 h, a figure consistent with the difference between the expected and the observed duration of incubation in the European cuckoo predicted from egg mass. Rather than being a specific adaptation to brood parasitism, internal incubation is a direct consequence of a protracted interval between ovulation (and fertilization) and laying, but because it results in early hatching may have predisposed certain species to become brood parasitic.
Proceedings of the Royal Society, Biological Sciences 2010: Letöltés
- Increased host tolerance of multiple cuckoo eggs leads to higher fledging success of the brood parasite (2009)
Csaba Moskát, Mark E. Hauber, Jesus M. Aviles, Miklós Bán, Rita Hargitai, Marcel Honza
Increased host tolerance of multiple cuckoo eggs leads to higher fledging success of the brood parasite
In birds, multiple parasitism is the laying of two or more eggs by one or more parasitic females in a single host nest. Several cognitive mechanisms may explain how multiple parasitism could affect parasite egg discrimination by hosts. Rejection based on discordance predicts that multiple parasitism provides a perceptually more error-prone way for hosts to reject parasitism because more foreign eggs decrease the chance that any one egg is perceived as most dissimilar and recognized as foreign, unless parasite eggs are all similarly highly nonmimetic. In contrast, rejection based on clutch uniformity predicts that in multiple parasitism egg rejection is more error-proof if mimicry by parasite eggs is variable, because increased variation in egg appearance makes for easier egg rejection for hosts. Finally, true egg recog- nition, that is, rejection based on memory of the host's own eggs, predicts no differences in rejection rates from nests with single or multiple parasitism. We studied common cuckoos, Cuculus canorus, parasitizing a population of great reed warblers, Acrocephalus arundinaceus, in Hungary where multiple parasitism was frequent. Hosts rejected parasite eggs less often in nests with multiple parasitism than in nests with single parasitism. These observations were confirmed by experimental parasitism and support the rejection based on discordance hypothesis. As hosts were more likely to tolerate cuckoo eggs in nests with multiple parasitism, we found that multiple parasitism more than doubled cuckoos' reproductive output per host nest compared to single parasitism.
Animal Behaviour 2009: Letöltés
- Egg Eviction Imposes a Recoverable Cost of Virulence in Chicks of a Brood Parasite (2009)
Michael G. Anderson, Csaba Moskát, Miklós Bán, Tomas Grim, Phillip Cassey, Mark E. Hauber
Egg Eviction Imposes a Recoverable Cost of Virulence in Chicks of a Brood Parasite
Background: Chicks of virulent brood parasitic birds eliminate their nestmates and avoid costly competition for foster parental care. Yet, efforts to evict nest contents by the blind and naked common cuckoo Cuculus canorus hatchling are counterintuitive as both adult parasites and large older cuckoo chicks appear to be better suited to tossing the eggs and young of the foster parents. Methodology/Principal Findings: Here we show experimentally that egg tossing imposed a recoverable growth cost of mass gain in common cuckoo chicks during the nestling period in nests of great reed warbler Acrocephalus arundinaceus hosts. Growth rates of skeletal traits and morphological variables involved in the solicitation of foster parental care remained similar between evictor and non-evictor chicks throughout development. We also detected no increase in predation rates for evicting nests, suggesting that egg tossing behavior by common cuckoo hatchlings does not increase the conspicuousness of nests. Conclusion: The temporary growth cost of egg eviction by common cuckoo hatchlings is the result of constraints imposed by rejecter host adults and competitive nestmates on the timing and mechanism of parasite virulence.
Plos One 2009: Letöltés
- Common Cuckoos (Cuculus Canorus) do not rely on indicators of parental abilities when searching for host nests: the importance of host defenses (2009)
Jesús M. Avilés, Csaba Moskát, Miklós Bán, Rita Hargitai and Deseada Parejo
Common Cuckoos (Cuculus Canorus) do not rely on indicators of parental abilities when searching for host nests: the importance of host defenses
There is widespread evidence that individuals within and among host populations are not evenly parasitized by Common Cuckoos (Cuculus canorus). We first investigated whether the song and nest size of a host species, the Great Reed Warbler (Acrocephalus arundinaceus), reveal information on parental abilities and level of defense against Common Cuckoos. Second, we analyzed whether female Common Cuckoos' preference for host nests is predicted by the degree of song expression and the nest size of the host. Earlier-breeding hosts built bigger nests, were more active singers, and had less rich syllable repertoires than late breeders. Host nestlings raised in a big nest received more feedings than those raised in a small nest. Host males that were active singers were paired with females that built bigger nests. All host pairs rejected nonmimetic artificial eggs, but those with a big nest were more prone to reject natural Common Cuckoo eggs. Thus, Great Reed Warbler pairs with a big nest were more willing to feed nestlings, but also had higher discriminatory abilities against Common Cuckoo eggs, than those with a small nest. These findings, and female Common Cuckoos' inability to capture the information provided by Great Reed Warblers' sexual signals, may explain why the females followed a simple rule of selecting the more visible host nests in the population.
The AUK 2009: Letöltés
- Experimental support for the use of egg uniformity in parasite egg discrimination by cuckoo hosts (2008)
Csaba Moskát & Jesús M. Avilés & Miklós Bán & Rita Hargitai & Anikó Zölei
Behavioral Ecology and Sociobiology
Experimental support for the use of egg uniformity in parasite egg discrimination by cuckoo hosts
Common cuckoo (Cuculus canorus) parasitism drastically reduces the reproductive success of their hosts and selects for host discrimination of cuckoo eggs. In a second stage of anti-parasite adaptation, once cuckoos can lay eggs that mimic those of their hosts, a high uniformity of host egg appearance within a clutch may favour cuckoo egg discrimination. Comparative evidence provides indirect support for this hypothesis although experimental support is currently lacking. Here, we studied the effect of experimentally decreased uniformity of host egg appearance on cuckoo egg discrimination by great reed warbler (Acrocephalus arundinaceus) hosts in a population in which long-term cuckoo parasitism has led to high levels of cuckooÂhost egg mimesis. We manipulated host clutch uniformity by adding extra spots to fresh host eggs just after they were laid. Rejection of non-mimetic experimental eggs added to these nests was compared with those in control nests in which uniformity was not altered. Previously, by over-painting real spots in a control group of nests, we showed a negligible effect of our paints on hosts' perception of their eggs. We show that for the great reed warbler, non-mimetic experimental eggs were relatively more tolerated in experimental nests, i.e. with lower unifor- mity (40%) than in control nests (5%). This is the first experimental study, to our knowledge, which demonstrates a reduced discrimination of foreign eggs as a consequence of an increase of egg phenotypes variation perception in a cuckoo host.
Behavioral Ecology and Sociobiology 2008: Letöltés
- Experimental shift in hosts' acceptance threshold of inaccurate-mimic brood parasite eggs (2006)
Márk E. Hauber, Csaba Moskát and Miklós Bán
Experimental shift in hosts' acceptance threshold of inaccurate-mimic brood parasite eggs
Hosts are expected to evolve resistance stra- tegies that efficiently detect and resist exposure to virulent parasites and pathogens. When rec- ognition is not error-proof, the acceptance threshold used by hosts to recognize parasites should be context dependent and become more restrictive with increasing predictability of parasitism. Here, we demonstrate that decisions of great reed warblers Acrocephalus arundinaceus to reject parasitism by the com- mon cuckoo Cuculus canorus vary adaptively within a single egg-laying bout. Hosts typically accept one of their own eggs with experimen- tally added spots and the background colour left visible. In contrast, hosts reject such spotted eggs when individuals had been previously exposed to and rejected one of their own eggs whose background colour had been entirely masked. These results support patterns of adaptive modulation of antiparasitic strategies through shifts in the acceptance threshold of hosts and suggest a critical role for experience in the discrimination decisions between inac- curate-mimic parasite eggs and hosts' own eggs.
Biology Letters 2006: Letöltés