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Mark E. Hauber - One of the best experts on this subject based on the ideXlab platform.
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aggressive responses of eastern phoebes sayornis phoebe and american robins turdus migratorius toward Brood Parasites and nest predators a model presentation experiment
The Wilson Journal of Ornithology, 2021Co-Authors: Janice K Enos, Julia Hyland Bruno, Mark E. HauberAbstract:Brood Parasites reduce the reproductive success of many bird species by laying eggs in their nests. Hosts that reject parasitic eggs (“rejecters”) avoid most costs of Brood parasitism altogether by physically ejecting eggs from nests or abandoning parasitized nesting attempts. Species that accept parasitic eggs once these are laid (“accepters”) may reduce or eliminate costs by aggressively responding to Brood Parasites at their nests to prevent parasitism from taking place. Accordingly, accepters should recognize Brood Parasites and nest predators as different nest threats with different levels of aggression, whereas rejecters may not. We exposed active Eastern Phoebe (Sayornis phoebe, an accepter host) and American Robin (Turdus migratorius, a rejecter host) nests to models of a female Brood parasitic Brown-headed Cowbird (Molothrus ater), an eastern chipmunk (Tamias striatus, nest predator), and a European Starling (Sturnus vulgaris, nonthreatening control) during the incubation stage. Phoebes alarm-called equally toward the nest predator and Brood Parasite models, but attacked the nest predator model more than the Brood Parasite model. Robins, in contrast, alarm-called toward and attacked all 3 models equally. Interpreting these results is challenging due to experimental design elements, specifically small sample sizes and restricting the experiment to the incubation stage. Nonetheless, our experiment contributes to the paucity of comparative studies on accepter versus rejecter nest defense behavior in response to both nest Parasites versus predators, and adds a new tested accepter species to the literature.
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physiological responses of host parents to rearing an avian Brood Parasite an experimental study
Hormones and Behavior, 2020Co-Authors: Nicholas D Antonson, Mark E. Hauber, Brett C Mommer, Jeffrey P Hoover, Wendy M SchelskyAbstract:Abstract Raising an obligate avian Brood Parasite is costly for host parents because it redirects valuable parental resources from one's own offspring to genetically unrelated young. The costs of raising a Brood Parasite may be mediated by physiological stressors for foster parents if it requires greater or biased parental effort compared to raising non-parasitized Broods. For example, upregulating glucocorticoid hormones or reducing immune responses may mediate a trade-off between resource allocation to a current Brood versus future reproductive opportunities, but published data on parasitized hosts' physiology are scarce. Here we used an experimental approach to test if host parents respond to the presence of Brood parasitic young through dynamic changes in their own physiology. We conducted our experiments with parasitic brown-headed cowbirds (Molothrus ater) fostered into nests of host prothonotary warblers (Protonotaria citrea). Relative to parents caring for non-parasitized control Broods, parasitism increased baseline corticosterone levels and reduced body mass in adult male, but not in female, hosts. Immune responses to a novel antigen were depressed in both parents of parasitized Broods compared to parents of non-parasitized Broods. Additionally, we found that immune function increased along the breeding season regardless of treatment. These experiments also confirmed prior observational data that parasitized adult males have reduced return rates to breeding sites in years subsequent to raising cowbirds. The findings demonstrate diverse physiological effects of parasitism on the foster parents in our particular host-Brood Parasite system, yet we found no evidence of individual trade-offs between endocrine and immune responses of adult hosts.
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endocrine regulation of egg rejection in an avian Brood Parasite host
Biology Letters, 2020Co-Authors: Mikus Abolinsabols, Mark E. HauberAbstract:Parasite–host coevolution can lead to novel behavioural adaptations in hosts to resist parasitism. In avian obligate Brood Parasite and host systems, many host species have evolved diverse cognitiv...
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When are egg-rejection cues perceived? A test using thermochromic eggs in an avian Brood Parasite host
Animal Cognition, 2019Co-Authors: Mark E. Hauber, Miri Dainson, Alec Luro, Amber A. Louder, Daniel HanleyAbstract:At the core of recognition systems research are questions regarding how and when fitness-relevant decisions made. Studying egg-rejection behavior by hosts to reduce the costs of avian Brood parasitism has become a productive model to assess cognitive algorithms underlying fitness-relevant decisions. Most of these studies focus on how cues and contexts affect hosts’ behavioral responses to foreign eggs; however, the timing of when the cues are perceived for egg-rejection decisions is less understood. Here, we focused the responses of American robins Turdus migratorius to model eggs painted with a thermochromic paint. This technique modified an egg’s color with predictably varying temperatures across incubation: at the onset of incubation, the thermochromic model egg was cold and perceptually similar to a static blue model egg (mimicking the robin’s own blue–green egg color), but by the end of an incubation bout, it was warm and similar to a static beige egg (mimicking the ground color of the egg of the robin’s Brood Parasite, the brown-headed cowbird Molothrus ater ). Thermochromic eggs were rejected at statistically intermediate rates between those of the static blue (mostly accepted) and static beige (mostly rejected) model eggs. This implies that at the population level, egg-rejection relevant cues are not perceived solely when arriving to or solely when departing from the nest. We also found that robins rejected their own eggs more often when exposed to color-changing model eggs relative to static eggs, suggesting that recognizing variable foreign eggs entails costly rejection errors for this host species.
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glucocorticoids mediate egg rejection in a Brood Parasite host
bioRxiv, 2019Co-Authors: Mikus Abolinsabols, Mark E. HauberAbstract:Abstract Avian Brood Parasites and their hosts are engaged in a coevolutionary battle that can result in the evolution of sophisticated trickery by Parasites and novel defence behaviours in hosts. Despite the clear evolutionary and ecological significance of host behaviour, however, we know very little about the mechanisms that regulate host defences, which limits our understanding of both inter- and intraspecific variation in host responses to parasitism. Here we tested whether corticosterone, a hormone known to be upregulated in hosts exposed to parasitism, also mediates one of the most frequent host defences – the rejection of foreign eggs. We experimentally reduced corticosterone levels in free-living Brood Parasite hosts, American robins Turdus migratorius, using mitotane and found that the likelihood of model egg rejection was significantly lower in the mitotane-treated birds relative to the sham-treated birds. These results demonstrate a causal link between glucocorticoids and egg rejection in hosts of avian Brood Parasites, but the physiological and sensory-cognitive pathways that regulate this effect remain unknown.
Marcel Honza - One of the best experts on this subject based on the ideXlab platform.
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Gut microbiota in a host–Brood Parasite system: insights from common cuckoos raised by two warbler species
FEMS Microbiology Ecology, 2020Co-Authors: Lucie Schmiedová, Marcel Honza, Milica Požgayová, Jakub Kreisinger, Jean-françois Martin, Petr ProchazkaAbstract:An animal's gut microbiota (GM) is shaped by a range of environmental factors affecting the bacterial sources invading the host. At the same time, animal hosts are equipped with intrinsic mechanisms enabling regulation of GM. However, there is limited knowledge on the relative importance of these forces. To assess the significance of host-intrinsic vs environmental factors, we studied GM in nestlings of an obligate Brood Parasite, the common cuckoo (Cuculus canorus), raised by two foster species, great reed warblers (Acrocephalus arundinaceus) and Eurasian reed warblers (A. scirpaceus), and compared these with GM of the fosterers' own nestlings. We show that fecal GM varied between cuckoo and warbler nestlings when accounting for the effect of foster/parent species, highlighting the importance of host-intrinsic regulatory mechanisms. In addition to feces, cuckoos also expel a deterrent secretion, which provides protection against olfactory predators. We observed an increased abundance of bacterial genera capable of producing repulsive volatile molecules in the deterrent secretion. Consequently, our results support the hypothesis that microbiota play a role in this antipredator mechanism. Interestingly, fosterer/parent identity affected only cuckoo deterrent secretion and warbler feces microbiota, but not that of cuckoo feces, suggesting a strong selection of bacterial strains in the GM by cuckoo nestlings.
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gut microbiota in a host Brood Parasite system insights from common cuckoos raised by two warbler species
FEMS Microbiology Ecology, 2020Co-Authors: Lucie Schmiedová, Marcel Honza, Milica Požgayová, Jakub Kreisinger, Jean-françois Martin, Petr ProchazkaAbstract:An animal's gut microbiota (GM) is shaped by a range of environmental factors affecting the bacterial sources invading the host. At the same time, animal hosts are equipped with intrinsic mechanisms enabling regulation of GM. However, there is limited knowledge on the relative importance of these forces. To assess the significance of host-intrinsic vs environmental factors, we studied GM in nestlings of an obligate Brood Parasite, the common cuckoo (Cuculus canorus), raised by two foster species, great reed warblers (Acrocephalus arundinaceus) and Eurasian reed warblers (A. scirpaceus), and compared these with GM of the fosterers' own nestlings. We show that fecal GM varied between cuckoo and warbler nestlings when accounting for the effect of foster/parent species, highlighting the importance of host-intrinsic regulatory mechanisms. In addition to feces, cuckoos also expel a deterrent secretion, which provides protection against olfactory predators. We observed an increased abundance of bacterial genera capable of producing repulsive volatile molecules in the deterrent secretion. Consequently, our results support the hypothesis that microbiota play a role in this antipredator mechanism. Interestingly, fosterer/parent identity affected only cuckoo deterrent secretion and warbler feces microbiota, but not that of cuckoo feces, suggesting a strong selection of bacterial strains in the GM by cuckoo nestlings.
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Caught on camera: circumstantial evidence for fatal mobbing of an avian Brood Parasite by a host
Journal of Vertebrate Biology, 2020Co-Authors: Michal Šulc, Petr Prochazka, Milica Požgayová, Kateřina Sosnovcová, Gabriela Štětková, Jan Studecký, Marcel HonzaAbstract:Hosts have evolved a multiplicity of defensive responses against avian Brood Parasites. One of them is mobbing behaviour which often includes direct contact attacks. These aggressive strikes may not only distract the Parasites but may also be fatal to them, as documented by cases of dead Brood Parasite females found near host nests. Here, we present the first video-recording of a great reed warbler (Acrocephalus arundinaceus) host whose vigorous nest defence appears to directly lead to the death of a female common cuckoo (Cuculus canorus). We suggest that the chance of Parasite death probably rises with the presence of unfavourable factors, such as water below the nest. Our observation supports previous suggestions that hosts may pose a lethal danger to their Parasites.
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mimicry cannot explain rejection type in a host Brood Parasite system
Animal Behaviour, 2019Co-Authors: Michal Šulc, Gabriela Štětková, Jolyon Troscianko, Anna E Hughes, Vaclav Jelinek, Miroslav Capek, Marcel HonzaAbstract:One of the most effective defensive strategies of hosts against Brood Parasites is rejection, commonly achieved by ejection of the parasitic egg or desertion of the parasitized nest. Nest desertion should be a costlier strategy than egg ejection, because birds must thesn spend additional time and energy renesting, and therefore we still cannot explain why some individuals desert their nests rather than eject parasitic eggs and continue a given breeding attempt. The great reed warbler, Acrocephalus arundinaceus, is a frequent host of the common cuckoo, Cuculus canorus, and is known to use both types of rejection response. By measuring cuckoo egg mimicry, we investigated the hypothesis that the hosts desert if they cannot reliably recognize the cuckoo egg in their nest. We predicted that we would find better mimicry when hosts deserted rather than ejected. However, we did not find a difference in mimicry between these two groups of nests, implying that host females do not desert because they cannot reliably recognize the parasitic egg. We also showed that neither the date in the season nor the age of the host females influenced the type of rejection. Other factors potentially eliciting nest desertion, including host personality, host, inability to eject, excessive clutch reduction and visibility of the cuckoo female at the host nest, are discussed. Finally, we suggest that desertion may persist as a host defensive strategy against Brood parasitism because it is not as costly as previously assumed and/or it is beneficial for host females in good physical condition.
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repeatability of host female and male aggression towards a Brood Parasite
Ethology, 2013Co-Authors: Alfred Trnka, Milica Požgayová, Peter Samas, Marcel HonzaAbstract:Current research on behavioural consistency showed that various types of animal behaviour are highly repeatable in the context of mate choice, exploration and parental care, including nest protection. However, the repeatability of aggressive nest defence has not yet been studied in hosts of Brood Parasites, although host aggression against adult Parasites represents a crucial line of antiparasitic defences. Here, we investigated the between-season repeatability of the great reed warbler (Acrocephalus arundinaceus) aggression towards a stuffed dummy of the Brood parasitic common cuckoo (Cuculus canorus). We found that under the relatively stable risk of Brood parasitism across breeding seasons, female responses to the cuckoo were highly repeatable, whereas male responses were variable. We suggest that the potential explanation for the observed patterns of female and male behaviours may lie in female's prominent roles in offspring care and nest protection, and in her lower renesting potential in comparison with that of males. However, further studies on the relationship between host aggression and other types of behaviours (host personality) and their fitness consequences under the fluctuating parasitism pressures are required to clarify the adaptive significance of aggressive behaviour observed in hosts of Brood Parasites.
Juan C Reboreda - One of the best experts on this subject based on the ideXlab platform.
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sex differences in learning flexibility in an avian Brood Parasite the shiny cowbird
Behavioural Processes, 2021Co-Authors: Jimena Loismilevicich, Alex Kacelnik, Mariano Cerrutti, Juan C ReboredaAbstract:Abstract Females of Brood parasitic shiny cowbirds, Molothrus bonariensis, search and prospect host nests, synchronizing parasitism with host laying. This behavior is sex-specific, as females perform this task without male's assistance. Host nests must be removed from the female’s memory "library" after being parasitized, to avoid repeated parasitism, or when they become unavailable because of predation. Thus, females must adjust their stored information about host nest status more dynamically than males, possibly leading to differences in learning flexibility. We tested for sex differences in a visual (local cues) and a spatial discrimination reversal learning task, expecting females to outperform males as an expression of greater behavioral flexibility. Both sexes learned faster the spatial than the visual task during both acquisition and reversal. In the visual task there were no sex differences in acquisition, but females reversed faster than males. In the spatial task there were no sex differences during either acquisition or reversal, possibly because of a ceiling effect: both sexes learned too fast for differences in performance to be detectable. Faster female reversal in a visual but not spatial task indicates that the greater behavioral flexibility in females may only be detectable above some level of task difficulty.
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genetic patterns of repeat and multiple parasitism by screaming cowbirds a specialist Brood Parasite
Animal Behaviour, 2020Co-Authors: Juan C Reboreda, Cynthia A Ursino, Meghan J Strong, Christina RiehlAbstract:Avian Brood Parasites lay their eggs in the nests of other species, leaving the hosts to care for the parasitic offspring. The bookkeeping hypothesis predicts that, in order to reduce competition between parasitic nestlings, female Parasites should keep a mental inventory of host nests that they have already parasitized and avoid laying multiple eggs in the same host nest. However, selection against repeat parasitism should be weaker when host nests are limited, or when hosts are able to rear more than one parasitic nestling. Here we use microsatellite genotyping of parasitic eggs to test whether female screaming cowbirds, Molothrus rufoaxillaris, avoid repeatedly parasitizing nests of their primary host, the greyish baywing, Agelaioides badius, in Argentina. Parasitism rates were extremely high (96.5% of 57 host clutches were parasitized with an average of 5.7 cowbird eggs each), indicating that host nests are limited. Although eggs laid by the same female showed moderate spatiotemporal clustering, individual females rarely laid more than one egg in the same host clutch (2 of 57 clutches, 26 of which contained multiple genotyped cowbird eggs). Females were much more likely to lay subsequent eggs in different host nests than to return to the same host nest. We found no evidence for kin structure among female cowbirds parasitizing the same host nest, which were no more closely related than chance would predict. These results suggest that female screaming cowbirds frequently lay eggs in host nests that have already been parasitized by unrelated females. However, they typically lay just one egg per host clutch, even though greyish baywings are capable of rearing several nestlings. Since screaming cowbird laying is often poorly synchronized with that of their host, avoidance of repeat parasitism may be adaptive if it allows females to spread the risk of failure among multiple host nests.
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molecular tracking of individual host use in the shiny cowbird a generalist Brood Parasite
Ecology and Evolution, 2016Co-Authors: Ma Alicia De La Colina, Juan C Reboreda, Mark E. Hauber, Bill M Strausberger, Bettina MahlerAbstract:Generalist Parasites exploit multiple host species at the population level, but the individual Parasite's strategy may be either itself a generalist or a specialist pattern of host species use. Here, we studied the relationship between host availability and host use in the individual parasitism patterns of the Shiny Cowbird Molothrus bonariensis, a generalist avian obligate Brood Parasite that parasitizes an extreme range of hosts. Using five microsatellite markers and an 1120-bp fragment of the mtDNA control region, we reconstructed full-sibling groups from 359 cowbird eggs and chicks found in nests of the two most frequent hosts in our study area, the Chalk-browed Mockingbird Mimus saturninus and the House Wren Troglodytes aedon. We were able to infer the laying behavior of 17 different females a posteriori and found that they were mostly faithful to a particular laying area and host species along the entire reproductive season and did not avoid using previously parasitized nests (multiple parasitism) even when other nests were available for parasitism. Moreover, we found females using the same host nest more than once (repeated parasitism), which had not been previously reported for this species. We also found few females parasitizing more than one host species. The use of an alternative host was not related to the main hosts' nest availability. Overall, female shiny cowbirds use a spatially structured and host species specific approach for parasitism, but they do so nonexclusively, resulting in both detectable levels of multiple parasitism and generalism at the level of individual Parasites.
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nest environment modulates begging behavior of a generalist Brood Parasite
Behavioral Ecology, 2016Co-Authors: Diego T Tuero, Ros Gloag, Juan C ReboredaAbstract:Fil: Tuero, Diego Tomas. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Ciudad Universitaria. Instituto de Ecologia, Genetica y Evolucion de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Ecologia, Genetica y Evolucion de Buenos Aires; Argentina
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reproductive success of the specialist Brood Parasite screaming cowbird in an alternative host the chopi blackbird
The Auk, 2015Co-Authors: Alejandro G Di Giacomo, Juan C ReboredaAbstract:ABSTRACT The Screaming Cowbird (Molothrus rufoaxillaris) is the most specialized Brood-parasitic cowbird, relying almost entirely on the Bay-winged Cowbird (Agelaioides badius) as host. Recently, Screaming Cowbirds have expanded their range to areas where Bay-winged Cowbirds are absent, and they are exploiting the Chopi Blackbird (Gnorimopsar chopi). Interactions between Screaming Cowbirds and Chopi Blackbirds are largely unexplored, as is the reproductive success of the Parasite in this host. Screaming Cowbirds, Chopi Blackbirds, and Bay-winged Cowbirds coexist in northeastern Argentina, providing an ideal system to explore interactions between a specialist Brood Parasite and an alternative host and to compare the reproductive success of the Parasite in its main host and in an alternative host. Screaming Cowbirds parasitized both hosts throughout their breeding seasons (Chopi Blackbirds, mid-October to mid-January; Bay-winged Cowbirds, mid-November to mid-March). Frequency of parasitism was lower in Chop...
John M Eadie - One of the best experts on this subject based on the ideXlab platform.
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an obligate Brood Parasite trapped in the intraspecific arms race of its hosts
Nature, 2004Co-Authors: Bruce E. Lyon, John M EadieAbstract:Reciprocal selection pressures often lead to close and adaptive matching of traits in coevolved species. A failure of one species to match the evolutionary trajectories of another is often attributed to evolutionary lags1,2 or to differing selection pressures across a geographic mosaic3,4. Here we show that mismatches in adaptation of interacting species—an obligate Brood parasitic duck and each of its two main hosts—are best explained by the evolutionary dynamics within the host species. Rejection of the Brood Parasite's eggs was common by both hosts, despite a lack of detectable cost of parasitism to the hosts. Egg rejection markedly reduced Parasite fitness, but egg mimicry experiments revealed no phenotypic natural selection for more mimetic parasitic eggs. These paradoxical results were resolved by the discovery of intraspecific Brood parasitism and conspecific egg rejection within the hosts themselves. The apparent arms race between species seems instead to be an incidental by-product of within-species conflict, with little recourse for evolutionary response by the Parasite.
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an obligate Brood Parasite trapped in the intraspecific arms race of its hosts
Nature, 2004Co-Authors: Bruce E. Lyon, John M EadieAbstract:Reciprocal selection pressures often lead to close and adaptive matching of traits in coevolved species. A failure of one species to match the evolutionary trajectories of another is often attributed to evolutionary lags1,2 or to differing selection pressures across a geographic mosaic3,4. Here we show that mismatches in adaptation of interacting species—an obligate Brood parasitic duck and each of its two main hosts—are best explained by the evolutionary dynamics within the host species. Rejection of the Brood Parasite's eggs was common by both hosts, despite a lack of detectable cost of parasitism to the hosts. Egg rejection markedly reduced Parasite fitness, but egg mimicry experiments revealed no phenotypic natural selection for more mimetic parasitic eggs. These paradoxical results were resolved by the discovery of intraspecific Brood parasitism and conspecific egg rejection within the hosts themselves. The apparent arms race between species seems instead to be an incidental by-product of within-species conflict, with little recourse for evolutionary response by the Parasite.
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paternity parasitism trade offs a model and test of host Parasite cooperation in an avian conspecific Brood Parasite
Evolution, 2002Co-Authors: Bruce E. Lyon, Wesley M Hochachka, John M EadieAbstract:Efforts to evaluate the evolutionary and ecological dynamics of conspecific Brood parasitism in birds and other animals have focused on the fitness costs of parasitism to hosts and fitness benefits to Parasites. However, it has been speculated recently that, in species with biparental care, host males might cooperate with parasitic females by allowing access to the host nest in exchange for copulations. We develop a cost-benefit model to explore the conditions under which such host-Parasite cooperation might occur. When the Brood Parasite does not have a nest of her own, the only benefit to the host male is siring some of the parasitic eggs (quasi-parasitism). Cooperation with the Parasite is favored when the ratio of host male paternity of his own eggs relative to his paternity of parasitic eggs exceeds the cost of parasitism. When the Brood Parasite has a nest of her own, a host male can gain additional, potentially more important benefits by siring the high-value, low-cost eggs laid by the Parasite in her own nest. Under these conditions, host males should be even more likely to accept parasitic eggs in return for copulations with the parasitic female. We tested these predictions for American coots (Fulica americana), a species with a high frequency of conspecific Brood parasitism. Multilocus DNA profiling indicated that host males did not sire any of the parasitic eggs laid in host nests, nor did they sire eggs laid by the Parasite in her own nest. We used field estimates of the model parameters from a four-year study of coots to predict the minimum levels of paternity required for the costs of parasitism to be offset by the benefits of mating with Brood Parasites. Observed levels of paternity were significantly lower than those predicted under a variety of assumptions, and we reject the hypothesis that host males cooperated with parasitic females. Our model clarifies the specific costs and benefits that influence host-Parasite cooperation and, more generally, yields precise predictions about expected levels of host male paternity. These predictions will enable a more rigorous assessment of field studies designed to test adaptive hypotheses of host-Parasite cooperation.
Naomi E. Langmore - One of the best experts on this subject based on the ideXlab platform.
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social learning of a Brood Parasite by its host
Biology Letters, 2013Co-Authors: William E Feeney, Naomi E. LangmoreAbstract:Arms races between Brood Parasites and their hosts provide model systems for studying the evolutionary repercussions of species interactions. However, how naive hosts identify Brood Parasites as enemies remains poorly understood, despite its ecological and evolutionary significance. Here, we investigate whether young, cuckoo-naive superb fairy-wrens, Malurus cyaneus, can learn to recognize cuckoos as a threat through social transmission of information. Naive individuals were initially unresponsive to a cuckoo specimen, but after observing conspecifics mob a cuckoo, they made more whining and mobbing alarm calls, and spent more time physically mobbing the cuckoo. This is the first direct evidence that naive hosts can learn to identify Brood Parasites as enemies via social learning.
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the frontline of avian Brood Parasite host coevolution
Animal Behaviour, 2012Co-Authors: William E Feeney, Justin A Welbergen, Naomi E. LangmoreAbstract:The interactions between avian interspecific Brood Parasites and their hosts provide tractable and informative systems for investigating coevolution. Generally, these investigations have emphasized the egg and chick stages of the coevolutionary arms race; however, recent studies demonstrate that coevolution operates at all stages of the host nesting cycle and emphasize the importance of reciprocal adaptations prior to deposition of the Parasite egg in the host nest: the ‘frontline’ of the arms race. Here we review the diversity of adaptations at the frontline and its implications for our understanding of Brood Parasite–host relationships. Coevolution at the frontline can fundamentally shape the life histories, morphologies, physiologies and behaviours of both Brood Parasites and their hosts, and influences the trajectories and outcomes of their subsequent coevolutionary interactions. We advocate the incorporation of frontline interactions in empirical and theoretical investigations of Brood Parasite–host arms races to provide a more holistic understanding of the coevolutionary processes in these systems.
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escalation of a coevolutionary arms race through host rejection of Brood parasitic young
Nature, 2003Co-Authors: Naomi E. Langmore, Sarah Hunt, Rebecca M KilnerAbstract:Cuckoo nestlings that evict all other young from the nest soon after hatching impose a high reproductive cost on their hosts1. In defence, hosts have coevolved strategies to prevent Brood parasitism. Puzzlingly, they do not extend beyond the egg stage2,3,4,5. Thus, hosts adept at recognizing foreign eggs remain vulnerable to exploitation by cuckoo nestlings6,7. Here we show that the breach of host egg defences by cuckoos creates a new stage in the coevolutionary cycle. We found that defences used during the egg-laying period by host superb fairy-wrens (Malurus cyaneus) are easily evaded by the Horsfield's bronze-cuckoo (Chrysococcyx basalis), a specialist fairy-wren Brood Parasite. However, although hosts never deserted their own Broods, they later abandoned 40% of nests containing a lone Horsfield's bronze-cuckoo nestling, and 100% of nests with a lone shining bronze-cuckoo nestling (Chrysococcyx lucidus), an occasional fairy-wren Brood Parasite. Our experiments demonstrate that host discrimination against evictor-cuckoo nestlings is possible, and suggest that it has selected for the evolution of nestling mimicry in bronze-cuckoos.
