scholarly journals Host–parasite coevolution beyond the nestling stage? Mimicry of host fledglings by the specialist screaming cowbird

2012 ◽  
Vol 279 (1742) ◽  
pp. 3401-3408 ◽  
Author(s):  
María C. De Mársico ◽  
Mariela G. Gantchoff ◽  
Juan C. Reboreda
Keyword(s):  
Survival Rates ◽  
Plumage Colour ◽  
Brood Parasite ◽  
Primary Host ◽  
Brood Parasites ◽  
Molothrus Bonariensis ◽  
Egg Mimicry ◽  
Host Parasite ◽  
Host Rejection

Egg mimicry by obligate avian brood parasites and host rejection of non-mimetic eggs are well-known textbook examples of host–parasite coevolution. By contrast, reciprocal adaptations and counteradaptations beyond the egg stage in brood parasites and their hosts have received less attention. The screaming cowbird ( Molothrus rufoaxillaris ) is a specialist obligate brood parasite whose fledglings look identical to those of its primary host, the baywing ( Agelaioides badius ). Such a resemblance has been proposed as an adaptation in response to host discrimination against odd-looking young, but evidence supporting this idea is scarce. Here, we examined this hypothesis by comparing the survival rates of young screaming cowbirds and non-mimetic shiny cowbirds ( Molothrus bonariensis ) cross-fostered to baywing nests and quantifying the similarity in plumage colour and begging calls between host and cowbird fledglings. Shiny cowbirds suffered higher post-fledging mortality rates (83%) than screaming cowbirds (0%) owing to host rejection. Visual modelling revealed that screaming cowbirds, but not shiny cowbirds, were indistinguishable from host young in plumage colour. Similarly, screaming cowbirds matched baywings' begging calls more closely than shiny cowbirds. Our results strongly support the occurrence of host fledgling mimicry in screaming cowbirds and suggest a role of visual and vocal cues in fledgling discrimination by baywings.

scholarly journals Host alarm calls attract the unwanted attention of the brood parasitic common cuckoo

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Attila Marton ◽  
Attila Fülöp ◽  
Katalin Ozogány ◽  
Csaba Moskát ◽  
Miklós Bán
Keyword(s):  
Bird Species ◽  
Context Dependency ◽  
Visual Signals ◽  
Alarm Calls ◽  
Primary Host ◽  
Nest Location ◽  
Brood Parasites ◽  
Body Of Knowledge ◽  
Vantage Points

AbstractIt is well known that avian brood parasites lay their eggs in the nests of other bird species, called hosts. It remains less clear, however, just how parasites are able to recognize their hosts and identify the exact location of the appropriate nests to lay their eggs in. While previous studies attributed high importance to visual signals in finding the hosts’ nests (e.g. nest building activity or the distance and direct sight of the nest from vantage points used by the brood parasites), the role of host acoustic signals during the nest searching stage has been largely neglected. We present experimental evidence that both female and male common cuckoos Cuculus canorus pay attention to their host’s, the great reed warbler’s Acrocephalus arundinaceus alarm calls, relative to the calls of an unparasitized species used as controls. Parallel to this, we found no difference between the visibility of parasitized and unparasitized nests during drone flights, but great reed warblers that alarmed more frequently experienced higher rates of parasitism. We conclude that alarm calls might be advantageous for the hosts when used against enemies or for alerting conspecifics, but can act in a detrimental manner by providing important nest location cues for eavesdropping brood parasites. Our results suggest that host alarm calls may constitute a suitable trait on which cuckoo nestlings can imprint on to recognize their primary host species later in life. Our study contributes to the growing body of knowledge regarding the context-dependency of animal signals, by providing a novel example of a beneficial acoustic trait intercepted by a heterospecific and used against the emitter.

scholarly journals Evidence for aggressive mimicry in an adult brood parasitic bird, and generalized defences in its host

2015 ◽  
Vol 282 (1810) ◽  
pp. 20150795 ◽  
Author(s):  
W. E. Feeney ◽  
J. Troscianko ◽  
N. E. Langmore ◽  
C. N. Spottiswoode
Keyword(s):  
Reproductive Cycle ◽  
Adult Bird ◽  
Plumage Colour ◽  
Quantitative Evidence ◽  
Brood Parasites ◽  
Aggressive Mimicry ◽  
Host Parasite ◽  
Do So

Mimicry of a harmless model (aggressive mimicry) is used by egg, chick and fledgling brood parasites that resemble the host's own eggs, chicks and fledglings. However, aggressive mimicry may also evolve in adult brood parasites, to avoid attack from hosts and/or manipulate their perception of parasitism risk. We tested the hypothesis that female cuckoo finches ( Anomalospiza imberbis ) are aggressive mimics of female Euplectes weavers, such as the harmless, abundant and sympatric southern red bishop ( Euplectes orix ). We show that female cuckoo finch plumage colour and pattern more closely resembled those of Euplectes weavers (putative models) than Vidua finches (closest relatives); that their tawny-flanked prinia ( Prinia subflava ) hosts were equally aggressive towards female cuckoo finches and southern red bishops, and more aggressive to both than to their male counterparts; and that prinias were equally likely to reject an egg after seeing a female cuckoo finch or bishop, and more likely to do so than after seeing a male bishop near their nest. This is, to our knowledge, the first quantitative evidence for aggressive mimicry in an adult bird, and suggests that host–parasite coevolution can select for aggressive mimicry by avian brood parasites, and counter-defences by hosts, at all stages of the reproductive cycle.

scholarly journals A Comparative Study of Shiny Cowbird Parasitism of Two Large Hosts, the Chalk-Browed Mockingbird and the Rufous-Bellied Thrush

The Condor ◽  
2003 ◽  
Vol 105 (4) ◽  
pp. 728-736 ◽  
Author(s):  
Paula Sackmann ◽  
Juan Carlos Reboreda
Keyword(s):  
Hatching Success ◽  
Nest Survival ◽  
Host Defenses ◽  
Chick Survival ◽  
Egg Survival ◽  
Brood Parasites ◽  
Molothrus Bonariensis ◽  
Cowbird Parasitism ◽  
Egg Destruction ◽  
Host Parasite

AbstractIt is usually accepted that generalist brood parasites should avoid using hosts larger than themselves because host chicks may outcompete parasite chicks for food. We studied the interactions between the Shiny Cowbird (Molothrus bonariensis) and two common hosts larger than the parasite, the Chalk-browed Mockingbird (Mimus saturninus) and the Rufous-bellied Thrush (Turdus rufiventris). For each host we determined (1) frequency and intensity of parasitism during the breeding season, (2) nesting success, egg survival, hatching success, and chick survival in unparasitized and parasitized nests, and (3) antiparasitic defenses. We also determined Shiny Cowbird egg survival, hatching success, and chick survival in both hosts. Parasitism reached 50% in mockingbirds and 66% in thrushes. In both species the main cost of parasitism was egg destruction through punctures. Hatching success, survival of host chicks, and nest survival did not differ between unparasitized and parasitized nests. Both hosts rejected parasitic white-morph eggs but accepted spotted-morph ones, even though they were significantly smaller than host eggs. The proportion of cowbirds fledged per egg laid in successful mockingbird and thrush nests was 0.4 and 0.6, respectively. Considering nest survival, reproductive success of Shiny Cowbirds was 0.15 in mockingbird nests and 0.17 in thrush nests. These values are similar to or higher than cowbird success with smaller hosts. Our results indicate that host quality is not only determined by host-parasite differences in body size, and that other factors, such as host defenses and nest survivorship, should be considered.Un Estudio Comparado del Parasitismo de Molothrus bonariensis en dos Hospedadores de Gran Tamaño, Mimus saturninus y Turdus rufiventrisResumen. Es aceptado generalmente que los parásitos de cría generalistas deberían evitar utilizar hospedadores de mayor tamaño corporal porque los pichones del hospedador podrían desplazar a sus pichones en la competencia por alimento. Se estudiaron las interacciones entre Molothrus bonariensis y dos hospedadores frecuentes de mayor tamaño que el parásito, Mimus saturninus y Turdus rufiventris. Para cada hospedador se determinó (1) frecuencia e intensidad de parasitismo durante la temporada reproductiva, (2) éxito de nidificación, supervivencia de huevos, éxito de eclosión y supervivencia de pichones en nidos no parasitados y parasitados, y (3) defensas antiparasitarias. También se determinó el éxito reproductivo del parásito en ambos hospedadores. El porcentaje de nidos parasitados fue 50% en Mimus saturninus y 66% en Turdus rufiventris. En ambas especies, el principal costo del parasitismo fue la destrucción de huevos por picaduras. El éxito de eclosión, la supervivencia de pichones y el éxito de nidificación fueron semejantes entre nidos no parasitados y parasitados. Ambos hospedadores rechazaron los huevos parásitos del morfo blanco pero aceptaron los del morfo manchado, si bien éstos fueron de menor tamaño que los del hospedador. La proporción de volantones de Molothrus bonariensis por huevo puesto en nidos exitosos de Mimus saturninus y Turdus rufiventris fue 0.4 y 0.6, respectivamente. Considerando la supervivencia de los nidos, el éxito reproductivo fue 0.15 en Mimus saturninus y 0.17 en Turdus rufiventris. Estos valores son similares o mayores que los reportados para hospedadores de menor tamaño que el parásito. Nuestros resultados indican que la calidad del hospedador no está sólo determinada por las diferencias en tamaño corporal entre el hospedador y el parásito y que otros factores, como defensas del hospedador y supervivencia de los nidos, deberían ser considerados.

scholarly journals How to evade a coevolving brood parasite: egg discrimination versus egg variability as host defences

2011 ◽  
Vol 278 (1724) ◽  
pp. 3566-3573 ◽  
Author(s):  
Claire N. Spottiswoode ◽  
Martin Stevens
Keyword(s):  
Visual Cues ◽  
Field Experiments ◽  
Brood Parasite ◽  
Arms Races ◽  
Egg Discrimination ◽  
Fitness Advantage ◽  
Evolutionary Trajectories ◽  
Negative Frequency Dependent Selection ◽  
Egg Mimicry ◽  
Host Rejection

Arms races between avian brood parasites and their hosts often result in parasitic mimicry of host eggs, to evade rejection. Once egg mimicry has evolved, host defences could escalate in two ways: (i) hosts could improve their level of egg discrimination; and (ii) negative frequency-dependent selection could generate increased variation in egg appearance (polymorphism) among individuals. Proficiency in one defence might reduce selection on the other, while a combination of the two should enable successful rejection of parasitic eggs. We compared three highly variable host species of the Afrotropical cuckoo finch Anomalospiza imberbis , using egg rejection experiments and modelling of avian colour and pattern vision. We show that each differed in their level of polymorphism, in the visual cues they used to reject foreign eggs, and in their degree of discrimination. The most polymorphic host had the crudest discrimination, whereas the least polymorphic was most discriminating. The third species, not currently parasitized, was intermediate for both defences. A model simulating parasitic laying and host rejection behaviour based on the field experiments showed that the two host strategies result in approximately the same fitness advantage to hosts. Thus, neither strategy is superior, but rather they reflect alternative potential evolutionary trajectories.

scholarly journals Breeding Success of a Specialist Brood Parasite, the Screaming Cowbird, Parasitizing an Alternative Host

The Condor ◽  
2003 ◽  
Vol 105 (1) ◽  
pp. 63-72 ◽  
Author(s):  
Myriam E. Mermoz ◽  
Gustavo J. Fernández
Keyword(s):  
Reproductive Success ◽  
Growth Rates ◽  
Breeding Success ◽  
Survival Rates ◽  
Alternative Host ◽  
Brood Parasite ◽  
Molothrus Bonariensis ◽  
Daily Survival ◽  
Differential Reproductive Success ◽  
Agelaioides Badius

Abstract The Screaming Cowbird (Molothrus rufoaxillaris) is a specialized brood parasite that primarily parasitizes the Bay-winged Cowbird, (Agelaioides badius; Screaming Cowbirds parasitize 80–100% of this species' nests). In contrast, the Shiny Cowbird (M. bonariensis) parasitizes more than 200 hosts. According to the differential reproductive success hypothesis, we expect that Screaming Cowbirds would have a lower reproductive success than Shiny Cowbirds when parasitizing other hosts. We assessed the breeding success of the Screaming Cowbird using an alternative host, the Brown-and-yellow Marshbird (Pseudoleistes virescens). This species is a common host of the Shiny Cowbird with 60–70% of nests parasitized, and is also regularly parasitized by the Screaming Cowbird but with lower frequency (6–20% of the nests). We compared the breeding success of Screaming and Shiny Cowbirds parasitizing this host species. No differences were found in the number of fledglings produced per egg laid between cowbird species. About 8–10% of cowbird eggs produced fledglings. The daily survival rate of Screaming Cowbird eggs was higher than daily survival rates for Shiny Cowbird eggs, but no differences were detected in the nestling daily survival rates. Moreover, we could not detect any difference in the hatching success (nestlings per egg), fledging success (fledglings per nestling), or growth rates of the two parasitic cowbird chicks. Furthermore, breeding success and growth rates of Screaming Cowbird chicks were similar to those previously reported while parasitizing the Bay-winged Cowbird. Our results are not consistent with the differential reproductive success hypothesis proposed as an explanation for the specialized parasitism of Screaming Cowbirds. Éxito Reproductivo del Parásito de Cría Especialista, Molothrus rufoaxillaris, Parasitando un Hospedador Alternativo Resumen. Molothrus rufoaxillaris es un parásito de cría especialista que parasita principalmente a Agelaioides badius (80–100% de los nidos son parasitados). Contrariamente, Molothrus bonariensis parasita más de 200 especies. Basándonos en la hipótesis del éxito reproductivo diferencial, esperamos que M. rufoaxillaris tenga un menor éxito reproductivo que M. bonariensis al parasitar a otros hospedadores. En este trabajo evaluamos el éxito reproductivo de M. rufoaxillaris parasitando un hospedador alternativo, Pseudoleistes virescens. Esta especie es un hospedador común de M. bonariensis con 60–70% de los nidos parasitados, y es también regularmente parasitado por M. rufoaxillaris pero con menor frecuencia (6–20% de los nidos). Comparamos el éxito reproductivo de M. rufoaxillaris y M. bonariensis parasitando esta especie. No encontramos diferencias en el número de volantones producidos por huevo puesto entre ambos parásitos. Alrededor del 8–10% de los huevos puestos por los Molothrus produjeron volantones. La tasa de supervivencia diaria de los huevos de M. rufoaxillaris fue más alta que la de huevos de M. bonariensis. Tampoco encontramos diferencias en el éxito de eclosión (pichón por huevo), éxito de emplumamiento (volantón por pichón), ni en las tasas de crecimiento de los pichones de Molothrus. Además, el éxito reproductivo de M. rufoaxillaris y las tasas de crecimiento de sus pichones fueron similares a las previamente descritas cuando parasita a A. badius. En consecuencia, nuestros resultados no avalan la hipótesis del éxito reproductivo diferencial para explicar la especialización en el parasitismo de M. rufoaxillaris.

scholarly journals Imperfect mimicry of host begging calls by a brood parasitic cuckoo: a cue for nestling rejection by hosts?

2021 ◽  
Author(s):  
Hee-Jin Noh ◽  
Ros Gloag ◽  
Ana V Leitão ◽  
Naomi E Langmore
Keyword(s):  
Visual Cues ◽  
Brood Parasite ◽  
Primary Host ◽  
Brood Parasites ◽  
Vocal Cues ◽  
Call Structure ◽  
Vocal Mimicry ◽  
Nestling Period ◽  
Imperfect Mimicry

Abstract Coevolutionary interactions between avian brood parasites and their hosts often lead to the evolution of discrimination and rejection of parasite eggs or chicks by hosts based on visual cues, and the evolution of visual mimicry of host eggs or chicks by brood parasites. Hosts may also base rejection of brood parasite nestlings on vocal cues, which would in turn select for mimicry of host begging calls in brood parasite chicks. In cuckoos that exploit multiple hosts with different begging calls, call structure may be plastic, allowing nestlings to modify their calls to match those of their various hosts, or fixed, in which case we would predict either imperfect mimicry or divergence of the species into host-specific lineages. In our study of the little bronze-cuckoo Chalcites minutillus and its primary host, the large-billed gerygone Gerygone magnirostris, we tested whether: (a) hosts use nestling vocalisations as a cue to discriminate cuckoo chicks; (b) cuckoo nestlings mimic the host begging calls throughout the nestling period; and (c) the cuckoo begging calls are plastic, thereby facilitating mimicry of the calls of different hosts. We found that the begging calls of little bronze-cuckoos are most similar to their gerygone hosts shortly after hatching (when rejection by hosts typically occurs) but become less similar as cuckoo chicks get older. Begging call structure may be used as a cue for rejection by hosts, and these results are consistent with gerygone defences selecting for age-specific vocal mimicry in cuckoo chicks. We found no evidence that little bronze-cuckoo begging calls were plastic.

scholarly journals Prognostic and Clinicopathological Significance of MiR-155 in Breast Cancer: A Systematic Review

2020 ◽  
Vol 21 (16) ◽  
pp. 5834
Author(s):  
Anna Maria Grimaldi ◽  
Silvia Nuzzo ◽  
Gerolama Condorelli ◽  
Marco Salvatore ◽  
Mariarosaria Incoronato
Keyword(s):  
Breast Cancer ◽  
Systematic Review ◽  
Prognostic Biomarker ◽  
Survival Rates ◽  
Prognostic Significance ◽  
Unmet Need ◽  
Non Invasive ◽  
Clinicopathological Significance ◽  
Present Systematic Review

There is an unmet need for novel non-invasive prognostic molecular tumour markers for breast cancer (BC). Accumulating evidence shows that miR-155 plays a pivotal role in tumorigenesis. Generally, miR-155 is considered an oncogenic miRNA promoting tumour growth, angiogenesis and aggressiveness of BC. Therefore, many researchers have focused on its use as a prognostic biomarker and therapeutic target. However, its prognostic value for BC patients remains controversial. To address this issue, the present systematic review aims to summarize the available evidence and give a picture of a prognostic significance of miR-155 in BC pathology. All eligible studies were searched on PubMed and EMBASE databases through various search strategies. Starting from 289 potential eligible records, data were examined from 28 studies, comparing tissue and circulating miR-155 expression levels with clinicopathological features and survival rates in BC patients. We discuss the pitfalls and challenges that need to be assessed to understand the power of miR-155 to respond to real clinical needs, highlighting the consistency, robustness or lack of results obtained to sate in translating this molecule to clinical practice. Our paper suggests that the prognostic role of miR-155 in the management of BC needs to be further verified.

scholarly journals Glioma Revisited: From Neurogenesis and Cancer Stem Cells to the Epigenetic Regulation of the Niche

2012 ◽  
Vol 2012 ◽  
pp. 1-20 ◽  
Author(s):  
Felipe de Almeida Sassi ◽  
Algemir Lunardi Brunetto ◽  
Gilberto Schwartsmann ◽  
Rafael Roesler ◽  
Ana Lucia Abujamra
Keyword(s):  
Stem Cells ◽  
Cancer Stem Cells ◽  
Cellular Proliferation ◽  
Survival Rates ◽  
Comprehensive Analysis ◽  
Heterogeneous Population ◽  
Aggressive Tumor ◽  
Epigenetic Modulation ◽  
The Brain

Gliomas are the most incident brain tumor in adults. This malignancy has very low survival rates, even when combining radio- and chemotherapy. Among the gliomas, glioblastoma multiforme (GBM) is the most common and aggressive type, and patients frequently relapse or become refractory to conventional therapies. The fact that such an aggressive tumor can arise in such a carefully orchestrated organ, where cellular proliferation is barely needed to maintain its function, is a question that has intrigued scientists until very recently, when the discovery of the existence of proliferative cells in the brain overcame such challenges. Even so, the precise origin of gliomas still remains elusive. Thanks to new advents in molecular biology, researchers have been able to depict the first steps of glioma formation and to accumulate knowledge about how neural stem cells and its progenitors become gliomas. Indeed, GBM are composed of a very heterogeneous population of cells, which exhibit a plethora of tumorigenic properties, supporting the presence of cancer stem cells (CSCs) in these tumors. This paper provides a comprehensive analysis of how gliomas initiate and progress, taking into account the role of epigenetic modulation in the crosstalk of cancer cells with their environment.

scholarly journals Spleen Tyrosine Kinase Inhibition Modulates p53 Activity

2017 ◽  
Vol 10 ◽  
pp. 117906601773156 ◽  
Author(s):  
Mohammad Althubiti
Keyword(s):  
Tyrosine Kinase ◽  
Survival Rates ◽  
Lymphocytic Leukemia ◽  
Spleen Tyrosine Kinase ◽  
Ht1080 Cell ◽  
P53 Expression ◽  
Chemical Inhibitors ◽  
Dependent Mechanism

Spleen tyrosine kinase (SYK) is a cytoplasmic enzyme that promotes survival and proliferation of B cells. SYK inhibition has shown promising results in the treatment of arthritis and chronic lymphocytic leukemia (CLL). However, in other context, it has been shown that SYK overexpression in epithelial cancer cells induced senescence in p53-dependent mechanism, which underscored its antineoplastic activity in vitro. Here, we show that SYK was induced in response of DNA damage in parallel with p53 levels. In addition, using chemical inhibitors of SYK reduced p53 levels in HCT116 and HT1080 cell lines, which underlines the role of SYK inhibition on p53 activity. Furthermore, SYK inhibition modulated the cell growth, which resulted in a decreasing in cell death. Interestingly, SYK expression showed a positive prognosis in patients with solid tumors in correlations with their survival rates, as expected negative correlation was seen between SYK expression and survival rate of patients with CLL. In conclusion, these findings demonstrate that SYK inhibition modulates p53 expression and activity in HCT116 and HT1080 cells. Reconsidering using of SYK inhibitors in clinical setting in the future should be evaluated carefully in accordance with these findings to prevent the formation of secondary malignancies.

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