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Zhong G, Wan G, Zhang Y, Zhao H, Wang L, Liang W. Nest desertion as an anti-parasitism strategy in hosts selects for late egg-laying behavior in cuckoos. iScience 2023; 26:108156. [PMID: 37965152 PMCID: PMC10641250 DOI: 10.1016/j.isci.2023.108156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 07/13/2023] [Accepted: 10/04/2023] [Indexed: 11/16/2023] Open
Abstract
Studies have shown that brood parasites lay their eggs early in the egg-laying sequence of their hosts, providing them with the advantage of earlier hatching. However, common cuckoos (Cuculus canorus) appear to parasitize the nests of gray bushchat (Saxicola ferreus) during the late egg-laying stage. The bushchat often abandons parasitized nests in the early stages, but not in the late egg-laying stages, thus favoring late egg-laying by cuckoos. In this study, four experiments were conducted to determine whether gray bushchats employ a nest desertion strategy targeted at cuckoo parasitism. The results showed that nest desertion was significantly correlated with parasitism cues and occurred mainly during the hosts' early egg-laying stage. Our study provides the first experimental evidence that nest desertion is an anti-parasitic strategy used by hosts in response to cuckoos. Additionally, our experiments demonstrated that the nest desertion is influenced by the trade-offs of investments in different egg-laying stages.
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Affiliation(s)
- Guo Zhong
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Guixia Wan
- School of Life Sciences, Guizhou Normal University, Guiyang 550001, China
| | - Yuhan Zhang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Huahua Zhao
- School of Life Sciences, Guizhou Normal University, Guiyang 550001, China
| | - Longwu Wang
- School of Life Sciences, Guizhou Normal University, Guiyang 550001, China
| | - Wei Liang
- Ministry of Education Key Laboratory for Ecology of Tropical Islands, College of Life Sciences, Hainan Normal University, Haikou 571158, China
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2
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Crudele I, Hauber ME, Reboreda JC, Fiorini VD. Gradual changes in model shape affect egg-directed behaviours by parasitic shiny cowbirds Molothrus bonariensis in captivity. ROYAL SOCIETY OPEN SCIENCE 2023; 10:221477. [PMID: 37181795 PMCID: PMC10170346 DOI: 10.1098/rsos.221477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 04/11/2023] [Indexed: 05/16/2023]
Abstract
Eggs are critically important for avian reproduction as all birds are oviparous. Accordingly, the recognition and care of own eggs represent the cornerstones of avian breeding, whereas the elimination of foreign objects, including brood-parasitic eggs and non-egg items from the nest are known to also increase fitness by refocusing incubation effort on the parents' own eggs. But egg recognition also plays a role in some avian obligate brood parasites' reproductive strategy through the pecking of already present eggs in the hosts' clutch to reduce nestmate competition with the parasite's own hatchling. Here we tested egg shape recognition in this parasitic egg-pecking context by exposing two different series of 3D printed models to captive obligate brood-parasitic shiny cowbirds (Molothrus bonariensis) in artificial nests. Natural egg-shaped models were pecked more often compared with increasingly thinner models, but there was no effect of increasing angularity on pecking rates, implying that a natural, rather than an artificial, range of variability elicited adaptive responses from parasitic cowbirds.
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Affiliation(s)
- Ignacio Crudele
- Departamento de Ecología, Genética y Evolución and IEGEBA-UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
| | - Mark E. Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Juan C. Reboreda
- Departamento de Ecología, Genética y Evolución and IEGEBA-UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
| | - Vanina D. Fiorini
- Departamento de Ecología, Genética y Evolución and IEGEBA-UBA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II Ciudad Universitaria, Buenos Aires C1428EGA, Argentina
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3
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Zhang J, Santema P, Li J, Feeney WE, Deng W, Kempenaers B. The mere presence of cuckoos in breeding area alters egg-ejection decisions in Daurian redstarts. Behav Ecol 2022. [DOI: 10.1093/beheco/arac084] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Abstract
Brood parasitic cuckoos and their hosts serve as model systems for studying host–parasite coevolution. Egg-rejection behavior constitutes an effective defense against brood parasitism, but some host species show phenotypic plasticity in egg-rejection behavior. Direct exposure to a cuckoo near the nest can increase egg-rejection likelihood, and long-term studies have shown that increased the egg-rejection rates generally correlate with higher parasite prevalence. However, it remains unclear whether such increases result from interactions between parasites and hosts, as these can be surprisingly common, or whether the mere presence of cuckoos in the breeding area is sufficient. Daurian redstarts Phoenicurus auroreus are a common host of the common cuckoo Cuculus canorus that defend against cuckoo parasitism mainly by ejecting the parasitic egg from the nest. This species is unique, as its first breeding attempt of the year takes place before the arrival of cuckoos, excluding the possibility for direct interactions. We simulated the ambient presence of cuckoos or hoopoes Upupa epops (control) in sub-populations of redstarts during their first egg-laying period by presenting taxidermic models and playing back vocalizations. Redstarts in cuckoo-treated plots showed significantly higher egg-ejection rates than individuals in control plots, even though females in both groups were equally likely to recognize the parasitic egg. Among females that did recognize the parasitic egg, those exposed to the cuckoo treatment were more likely to eject it than those exposed to the control treatment. Our results demonstrate unequivocally that the mere presence of cuckoos in the environment is sufficient to provoke egg-ejection behavior.
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Affiliation(s)
- Jinggang Zhang
- Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University , XinjiekouWai Str. 19, Haidian District, Beijing 100875 , China
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology , Eberhard-Gwinner-Str. 8, Seewiesen 82319 , Germany
| | - Peter Santema
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology , Eberhard-Gwinner-Str. 8, Seewiesen 82319 , Germany
| | - Jianqiang Li
- School of Ecology and Nature Conservation, Beijing Forestry University , Qinghua E Rd. 35, Haidian District, Beijing 100083 , China
| | - William E Feeney
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology , Eberhard-Gwinner-Str. 8, Seewiesen 82319 , Germany
| | - Wenhong Deng
- Ministry of Education Key Laboratory for Biodiversity Sciences and Ecological Engineering, College of Life Sciences, Beijing Normal University , XinjiekouWai Str. 19, Haidian District, Beijing 100875 , China
| | - Bart Kempenaers
- Department of Behavioural Ecology and Evolutionary Genetics, Max Planck Institute for Ornithology , Eberhard-Gwinner-Str. 8, Seewiesen 82319 , Germany
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4
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Tumulty JP, Fouilloux CA, Vallejos JG, Bee MA. Predicting and measuring decision rules for social recognition in a Neotropical frog. Am Nat 2022; 200:E77-E92. [DOI: 10.1086/720279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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5
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Defensive adaptations to cuckoo parasitism in the black-browed reed warbler (Acrocephalus bistrigiceps): recognition and mechanism. Anim Cogn 2022; 25:1299-1306. [PMID: 35320446 DOI: 10.1007/s10071-022-01613-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2021] [Revised: 02/25/2022] [Accepted: 03/08/2022] [Indexed: 02/05/2023]
Abstract
Hosts of avian brood parasites suffer a high cost of reproductive loss due to parasitism, driving them to evolve a variety of anti-parasitic defenses. These defenses comprise a series of components, including the recognition of brood parasites and the eggs laid by the parasites, cues used for recognition, and the mechanisms on which these behaviors are based. In this study, we conducted egg recognition and nest intruder experiments to examine these components of anti-parasitic behavior in the black-browed reed warbler (Acrocephalus bistrigiceps), a rare host of the common cuckoo (Cuculus canorus). We found that the host possessed strong recognition capacity, rejecting 100% of parasitic eggs, and used a template-based mechanism for egg recognition. The host birds also rejected 80% of their own eggs on which artificial markings were added to the blunt pole; however, they accepted all eggs with the same manipulation on the sharp pole, implying that the blunt pole was an important recognition cue. Furthermore, the host exhibited stronger aggression to cuckoos than to harmless controls; a behavior specific to the incubation stage rather than the nestling stage. Therefore, the host was able to distinguish the cuckoo from other nest intruders as being a brood parasite. These results together help explain the near absence of cuckoo parasitism in black-browed reed warblers and provide new information concerning anti-parasitic defenses in this host species.
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6
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Turcotte-van de Rydt AV, Petalas C, Sblendorio JM, Pearl CA, Gill SA, Guigueno MF. Clutch Abandoning Parasitised Yellow Warblers Have Increased Circulating Corticosterone With No Effect of Past Corticosterone or Differences in Egg Maculation Characteristics. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.711732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Parental care can be costly to parents’ fitness. As such, abandonment of the current reproductive attempt may benefit potential future opportunities, maximising lifetime reproductive success. Obligate brood parasitism, a reproductive strategy in which parasites lay their eggs in the nests of other species and rely solely on them to raise the parasitic young, is an ideal system to study brood abandonment. Some parasitised host species have evolved anti-parasitic defences, notably clutch abandonment (egg burial and nest desertion), that may mitigate negative consequences of parasitism. Abandonment of clutches due to parasitism is not unlike abandonment of reproduction in times of stress, suggesting that host responses to parasitism could be triggered at least partly by elevated stress hormones that mediate individual decisions. Yet, the mechanistic basis for clutch abandonment remains unclear. Here, we experimentally parasitised clutches of yellow warblers (Setophaga petechia), a common host of the brown-headed cowbird (Molothrus ater), with model cowbird eggs to examine whether host circulating corticosterone (CORT) differed among females that accepted parasitic eggs or rejected them through clutch abandonment. We also assessed whether feather CORT, a measure of past corticosterone exposure, differed between accepters and abandoners. Finally, we investigated whether egg visual signals, specifically differences in maculation characteristics between model cowbird and host eggs, predicted abandonment of experimentally parasitised clutches. Circulating CORT was higher in females who abandoned their parasitised clutches, but not in those who accepted, relative to controls with no egg addition. Past stress and differences in maculation characteristics did not predict whether individuals accepted or abandoned experimentally parasitised clutches. Moreover, differences in maculation characteristics between the host and model cowbird eggs did not predict CORT levels or nest abandonment. Thus, parasitism with subsequent clutch abandonment may be associated with elevated circulating CORT, but neither past stress nor differences in maculation characteristics influenced abandonment. The combination of these results contributes to our understanding of the roles of corticosterone and egg visual signals in the context of clutch abandonment in brood parasitism specifically, and of parental care more broadly.
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7
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Hanley D, Moghaddame-Jafari B, Rutledge SL. Could diffuse coevolution explain the generic eggshell color of the brown-headed cowbird? Curr Zool 2021; 67:645-652. [PMID: 34805542 PMCID: PMC8599007 DOI: 10.1093/cz/zoab078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2021] [Accepted: 09/13/2021] [Indexed: 11/14/2022] Open
Abstract
The brown-headed cowbird (hereafter cowbird) is an avian brood parasite that produces an egg dissimilar to those produced by the majority of its diverse host community. The cowbird’s generic egg may result from a Jack-of-all-trades strategy; however, the evolutionary mechanisms that select for their generic eggs are unclear. Here we propose that the cowbird’s eggshell phenotypes have evolved via diffuse coevolution, which results from community-level selective pressures, rather than via pairwise coevolution that occurs between a particular host species and its brood parasite. Under diffuse coevolution the cowbird’s host community, with varying eggshell phenotypes and recognition abilities, would select for a cowbird eggshell phenotype intermediate to those of its host community. This selection is exerted by hosts that reject cowbird eggs, rather than those that accept them; therefore, we expect cowbird eggshell colors can be approximated by both the phenotypes and rejection abilities of their host community. Here we use eggshell reflectance data from 43 host species to demonstrate that the cowbird eggshell phenotypes are reasonably predicted (within 2 just noticeable differences) by the eggshell phenotypes and rejection rates of their hosts. These findings suggest that cowbird eggshell phenotypes, and potentially those of other some generalist parasites, may evolve via diffuse coevolution. Importantly, this research provides insight into the underlying evolutionary processes that explain observed phenotypic variation and provides a framework for studying selection on both specialist and generalist parasites’ traits.
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Affiliation(s)
- Daniel Hanley
- Department of Biology, George Mason University, Fairfax, VA 22030, USA
| | | | - Samantha L Rutledge
- Department of Biology, Mansfield University of Pennsylvania, Mansfield, PA 16933, USA.,Museum of Natural Science and Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA
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8
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Hanley D, Rutledge SL, Villa J. The Perceptual and Cognitive Processes That Govern Egg Rejection in Hosts of Avian Brood Parasites. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.702934] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Hosts of avian brood parasites are under intense selective pressure to prevent or reduce the cost of parasitism. Many have evolved refined egg discrimination abilities, which can select for eggshell mimicry in their parasite. A classic assumption underlying these coevolutionary dynamics is that host egg recognition depends on the perceivable difference between their own eggs and those of their parasite. Over the past two decades, the receptor noise-limited (RNL) model has contributed to our understanding of these coevolutionary interactions by providing researchers a method to predict a host’s ability to discriminate a parasite’s egg from its own. Recent research has shown that some hosts are more likely to reject brown eggs than blue eggs, regardless of the perceived differences to their own. Such responses suggest that host egg recognition may be due to perceptual or cognitive processes not currently predictable by the RNL model. In this perspective, we discuss the potential value of using the RNL model as a null model to explore alternative perceptual processes and higher-order cognitive processes that could explain how and why some hosts make seemingly counter-intuitive decisions. Further, we outline experiments that should be fruitful for determining the perceptual and cognitive processing used by hosts for egg recognition tasks.
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9
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Garcia JE, Rohr DH, Dyer AG. Colour Discrimination From Perceived Differences by Birds. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.639513] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The ability of visual generalists to see and perceive displayed colour signals is essential to understanding decision making in natural environments. Whilst modelling approaches have typically considered relatively simple physiological explanations of how colour may be processed, data on key bee species reveals that colour is a complex multistage perception largely generated by opponent neural representations in a brain. Thus, a biologically meaningful unit of colour information must consider the psychophysics responses of an animal engaged in colour decision making. We extracted previously collected psychophysics data for a Violet-Sensitive (VS) bird, the pigeon (Columba livia), and used a non-linear function that reliably represents the behavioural choices of hymenopteran and dipteran pollinators to produce the first behaviourally validated and biologically meaningful representation of how VS birds use colour information in a probabilistic way. The function describes how similar or dis-similar spectral information can lead to different choice behaviours in birds, even though all such spectral information is above discrimination threshold. This new representation of bird vision will enable enhanced modelling representations of how bird vision can sense and use colour information in complex environments.
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10
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Egg rejection changes with seasonal variation in risk of cuckoo parasitism in Daurian redstarts, Phoenicurus auroreus. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.03.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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11
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Abernathy VE, Johnson LE, Langmore NE. An Experimental Test of Defenses Against Avian Brood Parasitism in a Recent Host. Front Ecol Evol 2021. [DOI: 10.3389/fevo.2021.651733] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Theoretical studies predict that hosts of avian brood parasites should evolve defenses against parasitism in a matter of decades. However, opportunities to test these predictions are limited because brood parasites rarely switch to naïve hosts. Here, we capitalize on a recent host switch by the brood-parasitic Pacific Koel (Eudynamys orientalis) in eastern Australia, to investigate how quickly the Red Wattlebird (Anthochaera carunculata), a recent host that has been annexed by the koel within the last 90 years, can learn to recognize and mob adult cuckoos and evolve the ability to eject parasite eggs. Pacific Koel nestlings kill all host young, so there should be strong selection for hosts to evolve defenses. However, low parasitism rates and high egg recognition costs might slow the spread of egg ejection in our study populations, while adult parasite recognition should be able to spread more rapidly, as this defense has been shown to be a learned trait rather than a genetically inherited defense. We tested Red Wattlebirds at two sites where parasitism rate differed. As predicted, we found that the Red Wattlebird showed little or no ability to eject foreign model eggs at either site, whereas two historical hosts showed high levels of egg ejection at both sites. However, Red Wattlebirds responded significantly more aggressively to a koel mount than to mounts of a harmless control and nest predator at the site with the higher parasitism rate and gave significantly more alarm calls overall toward the koel mount. Our results support previous evidence that recognition and mobbing of a brood parasite are learned traits and may be especially beneficial to naïve hosts that have not had enough time or a high enough selection pressure to evolve egg rejection.
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12
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Turner AM, Hauber ME. The American robin (
Turdus migratorius
): A focal species for anti‐parasitic egg rejection studies among hosts of the brown‐headed cowbird (
Molothrus ater
). Ethology 2021. [DOI: 10.1111/eth.13158] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Affiliation(s)
- Abbigail M. Turner
- Department of Evolution, Ecology, and Behavior School of Integrative Biology University of Illinois at Urbana‐Champaign Urbana IL USA
| | - Mark E. Hauber
- Department of Evolution, Ecology, and Behavior School of Integrative Biology University of Illinois at Urbana‐Champaign Urbana IL USA
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13
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Scharf HM, Abolins-Abols M, Stenstrom KH, Tolman DT, Schelsky WM, Hauber ME. Exposure to a mimetic or non-mimetic model avian brood parasite egg does not produce differential glucocorticoid responses in an egg-accepter host species. Gen Comp Endocrinol 2021; 304:113723. [PMID: 33539900 DOI: 10.1016/j.ygcen.2021.113723] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 01/20/2021] [Accepted: 01/22/2021] [Indexed: 10/22/2022]
Abstract
Avian obligate brood parasitism, a reproductive strategy where a parasite lays its egg into the nest of another species, imposes significant fitness costs upon host parents and their offspring. To combat brood parasitism, many host species recognize and reject foreign eggs (rejecters), but others are accepters that raise the parasitic progeny. Some accepter hosts may be unable to grasp or pierce parasitic eggs even if they recognize them as foreign eggs in the clutch, whereas other accepters may not have evolved the cognitive skillsets to recognize dissimilar eggs in the nest. Here we assessed the endocrine responses of an accepter host species to model parasitic eggs to address these two alternatives. We experimentally parasitized nests of a locally common host of the brood-parasitic brown-headed cowbird (Molothrus ater), the prothonotary warbler (Protonotaria citrea; a cowbird-egg accepter), with a mimetic or non-mimetic model cowbird-sized egg. Our goal was to determine whether they perceived the non-mimetic egg as a greater stressor by measuring circulating corticosterone levels. We added eggs to nests during the incubation stage and obtained blood plasma samples from females on the nest 2 h later, using females with unmanipulated clutches as controls. Incubating females showed no differences in baseline plasma corticosterone levels between our different treatments. We conclude that exposure to foreign eggs does not activate the hypothalamic-pituitary-adrenal axis of prothonotary warbler hosts in this experimental paradigm.
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Affiliation(s)
- H M Scharf
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA.
| | - M Abolins-Abols
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA; Department of Biology, University of Louisville, KY, USA
| | - K H Stenstrom
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA
| | - D T Tolman
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA
| | - W M Schelsky
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, IL, USA
| | - M E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois Urbana-Champaign, IL, USA; Illinois Natural History Survey, Prairie Research Institute, University of Illinois Urbana-Champaign, IL, USA; Hanse-Wissenschaftskolleg (Institute for Advanced Study), Delmenhorst 27753, Germany
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14
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Hauber ME, Winnicki SK, Hoover JP, Hanley D, Hays IR. The limits of egg recognition: testing acceptance thresholds of American robins in response to decreasingly egg-shaped objects in the nest. ROYAL SOCIETY OPEN SCIENCE 2021; 8:201615. [PMID: 33614093 PMCID: PMC7890492 DOI: 10.1098/rsos.201615] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/06/2021] [Indexed: 05/28/2023]
Abstract
Some hosts of avian brood parasites reduce or eliminate the costs of parasitism by removing foreign eggs from the nest (rejecter hosts). In turn, even acceptor hosts typically remove most non-egg-shaped objects from the nest, including broken shells, fallen leaves and other detritus. In search for the evolutionary origins and sensory mechanisms of egg rejection, we assessed where the potential threshold between egg recognition and nest hygiene may lie when it comes to stimulus shape. Most previous studies applied comparisons of egg-sized objects with non-continuous variation in shape. Here, instead, we used two series of three-dimensional-printed objects, designed a priori to increasingly diverge from natural eggs along two axes (width or angularity) of shape variation. As predicted, we detected transitions from mostly acceptance to mostly rejection in the nests of American robins Turdus migratorius along each of the two axes. Our methods parallel previous innovations in egg-rejection studies through the use of continuous variation in egg coloration and maculation contrast, to better understand the sensory limits and thresholds of variation in egg recognition and rejection in diverse hosts of avian brood parasites.
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Affiliation(s)
- Mark E. Hauber
- Department of Evolution, Ecology, and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Program in Ecology, Evolution, and Conservation, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Sarah K. Winnicki
- Department of Evolution, Ecology, and Behavior, University of Illinois at Urbana-Champaign, Urbana, IL, USA
- Program in Ecology, Evolution, and Conservation, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Jeffrey P. Hoover
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Daniel Hanley
- Department of Biology, George Mason University, Fairfax, VA, USA
| | - Ian R. Hays
- Department of Biological Sciences; Rutgers, The State University of New Jersey, Newark, NJ, USA
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15
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Li D, Li X, Zhang Y, Guan S, Ruan Y. Contrasting effects of egg size and appearance on egg recognition and rejection response by Oriental reed warblers. Ecol Evol 2020; 10:10508-10519. [PMID: 33072276 PMCID: PMC7548169 DOI: 10.1002/ece3.6707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/14/2020] [Accepted: 07/29/2020] [Indexed: 11/07/2022] Open
Abstract
Background Among potential hosts, the rejection of foreign eggs, which is a common and effective strategy to counter brood parasitism, depends on egg recognition. Multimodal and multicomponent recognition cues of brood parasitic eggs, which include both tactile (size, shape, and texture) and visual (size, shape, color, and maculation) cues, are potentially involved in the perception and discrimination of foreign eggs by hosts. An egg rejection experiment on the host with different types of model eggs can help to accurately assess the relative contribution of different components on egg recognition and constraints to rejection, in which videos can help identify the method of host rejection. Methods Here, we assessed egg recognition and rejection responses by Oriental reed warblers (Acrocephalus orientalis), one of the most common hosts of common cuckoos (Cuculus canorus) which breed in eastern China. We designed six groups of model eggs for rejection experiments in which sensory cues included three grades of size and two categories of visual mimicry. Results Our experiments confirmed that the multimodal traits, which included variation in size, were significant predictors of egg rejection: We detected significantly higher rejection rates of mimetic spotted model eggs than of nonmimetic blue eggs. However, large model eggs did not yield higher rejection rates and, instead, these were less likely to be rejected and more likely to be deserted compared with smaller eggs. Further video‐recording data showed that there was no significant effect of egg size on the egg recognition rate (percentage of nests with evidence of egg pecking). No evidence that the egg appearance had an effect on the method of egg rejection (ejection or nest desertion) was found. Conclusions Only visual signals, such as color and maculation, contributed to the recognition of foreign eggs by Oriental reed warblers as recognizable clues, but not the egg size. The egg size had an impact on the type of egg rejection. It was less feasible for the warblers to eject large eggs and that is why they opted more often for desertion as the mean of model egg rejection. The significantly lower egg rejection rate of large eggs suggested that although some of them were recognized as foreign eggs, hosts failed to reject these eggs and finally the eggs were assumed to being accepted by the commonly used nest‐checking methods.
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Affiliation(s)
- Donglai Li
- School of Life SciencesLiaoning UniversityShenyangLiaoningChina
| | - Xiaoshuang Li
- School of Life SciencesLiaoning UniversityShenyangLiaoningChina
| | - Yan Zhang
- School of Life SciencesLiaoning UniversityShenyangLiaoningChina
| | - Shuang Guan
- School of Life SciencesLiaoning UniversityShenyangLiaoningChina
- Present address:
Changchun Longjia International AirportChangchunJilinChina
| | - Yanan Ruan
- School of Life SciencesLiaoning UniversityShenyangLiaoningChina
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16
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Luro AB, Fernández-Juricic E, Baumhardt P, Hauber ME. Visual acuity and egg spatial chromatic contrast predict egg rejection behavior of American robins. J Exp Biol 2020; 223:jeb229609. [PMID: 32895322 DOI: 10.1242/jeb.229609] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2020] [Accepted: 08/29/2020] [Indexed: 08/25/2023]
Abstract
Color and spatial vision is critical for recognition and discrimination tasks affecting fitness, including finding food and mates, and recognizing offspring. For example, as a counter defense to avoid the cost of raising the unrelated offspring of obligate interspecific avian brood parasites, many host species routinely view, recognize and remove the foreign egg(s) from their nests. Recent research has shown that host species visually attend to both chromatic and spatial pattern features of eggs; yet how hosts simultaneously integrate these features together when recognizing eggs remains an open question. Here, we tested egg rejection responses of American robins (Turdus migratorius) using a range of 3D-printed model eggs covered with blue and yellow checkered patterns differing in relative square sizes. We predicted that robins would reject a model egg if they could visually resolve the blue and yellow squares as separate features, or accept it if the squares blended together and appeared similar in color to the natural blue-green color of robin eggs as perceived by the avian visual system. As predicted, the probability of robins rejecting a model egg increased with greater sizes of its blue and yellow squares. Our results suggest that chromatic visual acuity and viewing distance have the potential to limit the ability of a bird to recognize a foreign egg in its nest, thus providing a limitation to host egg recognition that obligate interspecific avian brood parasites may exploit.
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Affiliation(s)
- Alec B Luro
- Department of Evolution, Ecology and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Esteban Fernández-Juricic
- Department of Biological Sciences, College of Science, Purdue University, West Lafayette, IN 47907, USA
| | - Patrice Baumhardt
- Department of Biological Sciences, College of Science, Purdue University, West Lafayette, IN 47907, USA
| | - Mark E Hauber
- Department of Evolution, Ecology and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
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17
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Suarez AV, Scharf HM, Reeve HK, Hauber ME. Signal detection, acceptance thresholds and the evolution of animal recognition systems. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190464. [PMID: 32420845 DOI: 10.1098/rstb.2019.0464] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Affiliation(s)
- A V Suarez
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - H M Scharf
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
| | - H K Reeve
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - M E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois at Urbana-Champaign, 515 Morrill Hall, 505 S. Goodwin Avenue, Urbana, IL 61801, USA
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18
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Tibbetts EA, Liu M, Laub EC, Shen SF. Complex signals alter recognition accuracy and conspecific acceptance thresholds. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190482. [PMID: 32420854 DOI: 10.1098/rstb.2019.0482] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Many aspects of behaviour depend on recognition, but accurate recognition is difficult because the traits used for recognition often overlap. For example, brood parasitic birds mimic host eggs, so it is challenging for hosts to discriminate between their own eggs and parasitic eggs. Complex signals that occur in multiple sensory modalities or involve multiple signal components are thought to facilitate accurate recognition. However, we lack models that explore the effect of complex signals on the evolution of recognition systems. Here, we use individual-based models with a genetic algorithm to test how complex signals influence recognition thresholds, signaller phenotypes and receiver responses. The model has three main results. First, complex signals lead to more accurate recognition than simple signals. Second, when two signals provide different amounts of information, receivers will rely on the more informative signal to make recognition decisions and may ignore the less informative signal. As a result, the particular traits used for recognition change over evolutionary time as sender and receiver phenotypes evolve. Third, complex signals are more likely to evolve when recognition errors are high cost than when errors are low cost. Overall, redundant, complex signals are an evolutionarily stable mechanism to reduce recognition errors. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
| | - Ming Liu
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan, Republic of China
| | - Emily C Laub
- Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI, USA
| | - Sheng-Feng Shen
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan, Republic of China
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19
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Avilés JM. Avian egg and nestling detection in the wild: should we rely on visual models or behavioural experiments? Philos Trans R Soc Lond B Biol Sci 2020; 375:20190485. [PMID: 32420848 DOI: 10.1098/rstb.2019.0485] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The fields of avian egg and nestling colour detection have rapidly advanced owing to the application of visual models, which have allowed assessing of evolutionary questions considering receiver perception. Here, I first review the literature aiming to identify patterns of avian visual model usage. Second, I elaborate on limitations in the application of the receptor-noise limited perceptual (RNL hereafter) model. A systematic literature review revealed that the RNL model was the most used approach (81% of studies) in the field, and that most studies (76%) were concerned with classic evolutionary questions in avian brood parasitism. Some known limitations of the RNL model deal with model assumptions and parameterization, or, a poor consideration of post-detection neural processes. Others, however, are specific of the fields of egg and nestling discrimination and deal with the highly variable nature of ambient light at the nests, the complex colour design of eggs and nestlings, the multi-dimensional nature of perception, and the possible implication of learning. I, therefore, conclude that visual models should be used with caution to establish inference about egg and nestling discrimination, and rather be used to provide reasonable hypotheses which need to be validated with behavioural experiments. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- Jesús M Avilés
- Department of Functional and Evolutionary Ecology, Spanish Council for Research (EEZA-CSIC), Carretera de Sacramento s/n, 04120, La Cañada de San Urbano, E04120 Almería, Spain
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20
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Scharf HM, Suarez AV, Reeve HK, Hauber ME. The evolution of conspecific acceptance threshold models. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190475. [PMID: 32420847 DOI: 10.1098/rstb.2019.0475] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
How do organisms balance different types of recognition errors when cues associated with desirable and undesirable individuals or resources overlap? This is a fundamental question of signal detection theory (SDT). As applied in sociobiology, SDT is not limited to a single context or animal taxon, therefore its application can span what may be considered dissimilar systems. One of the applications of SDT is the suite of acceptance threshold models proposed by Reeve (1989), which analysed how individuals should balance acceptance and rejection errors in social discrimination decisions across a variety of recognition contexts, distinguished by how these costs and benefits relatively combine. We conducted a literature review to evaluate whether these models' specific predictions have been upheld. By examining over 350 research papers, we quantify how Reeve's models (Reeve 1989 Am. Nat. 133, 407-435 (doi:10.1086/284926)) have influenced the field of ecological and behavioural recognition systems research. We found overall empirical support for the predictions of the specific models proposed by Reeve, and argue for further expansion of their applications into more diverse taxonomic and additional recognition contexts. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- Hannah M Scharf
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - Andrew V Suarez
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
| | - H Kern Reeve
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - Mark E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
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21
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Sheehan MJ, Reeve HK. Evolutionarily stable investments in recognition systems explain patterns of discrimination failure and success. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190465. [PMID: 32420853 DOI: 10.1098/rstb.2019.0465] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Many animals are able to perform recognition feats that astound us-such as a rodent recognizing kin it has never met. Yet in other contexts, animals appear clueless as when reed warblers rear cuckoo chicks that bear no resemblance to their own species. Failures of recognition when it would seem adaptive have been especially puzzling. Here, we present a simple tug-of-war game theory model examining how individuals should optimally invest in affecting the accuracy of discrimination between desirable and undesirable recipients. In the game, discriminating individuals (operators) and desirable and undesirable recipients (targets and mimics, respectively) can all invest effort into their own preferred outcome. We demonstrate that stable inaccurate recognition will arise when undesirable recipients have large fitness gains from inaccurate recognition relative to the pay-offs that the other two parties receive from accurate recognition. The probability of accurate recognition is often determined by just the relative pay-offs to the desirable and undesirable recipients, rather than to the discriminator. Our results provide a new lens on long-standing puzzles including a lack of nepotism in social insect colonies, tolerance of brood parasites and male birds caring for extra-pair young in their nests, which our model suggests should often lack accurate discrimination. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- Michael J Sheehan
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
| | - H Kern Reeve
- Department of Neurobiology and Behavior, Cornell University, Ithaca, NY 14853, USA
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22
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Ruiz-Raya F, Soler M. Signal detection and optimal acceptance thresholds in avian brood parasite-host systems: implications for egg rejection. Philos Trans R Soc Lond B Biol Sci 2020; 375:20190477. [PMID: 32420851 DOI: 10.1098/rstb.2019.0477] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Signal detection theory addresses the challenge of successfully identifying informative signals in noisy information contexts, allowing optimal behavioural decisions in diverse ecological contexts. The optimal acceptance threshold hypothesis proposed by Reeve (Reeve 1989 Am. Nat. 133, 407-435. (doi:10.1086/284926)) is an elegant theoretical model to predict the flexibility of acceptance thresholds for conspecific discrimination. This model has provided a robust framework used to explore recognition systems in a broad range of contexts such as animal communication, nest-mate discrimination or anti-parasitic host responses. In this review, we discuss key concepts related to the optimal acceptance threshold hypothesis applied to egg rejection decisions in avian brood parasite-host interactions. We explore those factors determining signal detectability in parasitized nests and how hosts adjust their rejection decisions to both the risk of parasitism and the potential costs associated with egg rejection. In addition, we discuss recent results that challenge some traditional assumptions of the optimal acceptance threshold hypothesis and provide a novel perspective to explore rejection decisions, such as the existence of single-threshold decision rules or acceptance decisions. An integrative view combining current evidence with traditional theory is needed to further advance the comprehension of optimal acceptance thresholds. This article is part of the theme issue 'Signal detection theory in recognition systems: from evolving models to experimental tests'.
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Affiliation(s)
- Francisco Ruiz-Raya
- Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spain
| | - Manuel Soler
- Departamento de Zoología, Facultad de Ciencias, Universidad de Granada, E-18071 Granada, Spain
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23
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Yang C, Si X, Liang W, Møller AP. Spatial variation in egg polymorphism among cuckoo hosts across 4 continents. Curr Zool 2020; 66:477-483. [PMID: 33293928 PMCID: PMC7705517 DOI: 10.1093/cz/zoaa011] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2019] [Accepted: 03/12/2020] [Indexed: 11/14/2022] Open
Abstract
Although egg color polymorphism has evolved as an effective defensive adaptation to brood parasitism, spatial variations in egg color polymorphism remain poorly characterized. Here, we investigated egg polymorphism in 647 host species (68 families and 231 genera) parasitized by 41 species of Old Word cuckoos (1 family and 11 genera) across Asia, Europe, Africa, and Australia. The diversity of parasitic cuckoos differs among continents, reflecting the continent-specific intensities of parasitic selection pressure on hosts. Therefore, host egg polymorphism is expected to evolve more frequently on continents with higher cuckoo diversity. We identified egg polymorphism in 24.1% of all host species and 47.6% of all host families. The common cuckoo Cuculus canorus utilized 184 hosts (28.4% of all host species). Hosts of the common cuckoo and of Chrysococcyx species were more likely to have polymorphic eggs than hosts parasitized by other cuckoos. Both the number of host species and the host families targeted by the cuckoo species were positively correlated with the frequency of host egg polymorphism. Most host species and most hosts exhibiting egg color polymorphism were located in Asia and Africa. Host egg polymorphism was observed less frequently in Australia and Europe. Our results also suggested that egg polymorphism tends to occur more frequently in hosts that are utilized by several cuckoo species or by generalist cuckoo species. We suggest that selection pressure on hosts from a given continent increases proportionally to the number of cuckoo species, and that this selection pressure may, in turn, favor the evolution of host egg polymorphism.
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Affiliation(s)
- Canchao Yang
- Ministry of Education Key Laboratory for Tropical Plant and Animal Ecology, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Xingfeng Si
- Zhejiang Tiantong Forest Ecosystem National Observation and Research Station, School of Ecological and Environmental Sciences, East China Normal University, Shanghai 200241, China.,Institute of Eco-Chongming (IEC), Shanghai 202162, China
| | - Wei Liang
- Ministry of Education Key Laboratory for Tropical Plant and Animal Ecology, College of Life Sciences, Hainan Normal University, Haikou 571158, China
| | - Anders Pape Møller
- Ecologie Systématique Evolution, Université Paris-Sud, CNRS, AgroParisTech, Université Paris-Saclay, F-91405 Orsay Cedex, France
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24
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Fitting different visual models to behavioral patterns of parasitic egg rejection along a natural egg color gradient in a cavity-nesting host species. Vision Res 2020; 167:54-59. [DOI: 10.1016/j.visres.2019.12.007] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2019] [Revised: 11/30/2019] [Accepted: 12/09/2019] [Indexed: 11/19/2022]
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25
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When are egg-rejection cues perceived? A test using thermochromic eggs in an avian brood parasite host. Anim Cogn 2019; 22:1141-1148. [PMID: 31515648 DOI: 10.1007/s10071-019-01306-w] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2019] [Revised: 08/27/2019] [Accepted: 09/04/2019] [Indexed: 01/27/2023]
Abstract
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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26
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Abolins-Abols M, Hanley D, Moskát C, Grim T, Hauber ME. Anti-parasitic egg rejection by great reed warblers (Acrocephalus arundinaceus) tracks differences along an eggshell color gradient. Behav Processes 2019; 166:103902. [PMID: 31283976 DOI: 10.1016/j.beproc.2019.103902] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Revised: 07/04/2019] [Accepted: 07/04/2019] [Indexed: 11/29/2022]
Abstract
One of the most effective defenses against avian brood parasitism is the rejection of the foreign egg from the host's nest. Until recently, most studies have tested whether hosts discriminate between own and foreign eggs based on the absolute differences in avian-perceivable eggshell coloration and maculation. However, recent studies suggest that hosts may instead contrast egg appearances across a directional eggshell color gradient. We assessed which discrimination rule best explained egg rejection by great reed warblers Acrocephalus arundinaceus, a frequent host to an egg-mimetic race of common cuckoos Cuculus canorus. We deployed 3D-printed model eggs varying in blue-green to brown coloration and in the presence of maculation. Using visual modeling, we calculated the absolute chromatic and achromatic just-noticeable differences (JNDs), as well as directional JNDs across a blue-green to brown egg color gradient, between host and model eggs. While most model eggs were rejected by great reed warblers, browner eggs were rejected with higher probability than more blue-green eggs, and the rejection probability did not depend on maculation. Directional egg color discrimination shown here and in a suite of recent studies on other host species may shape the cognitive decision rules that hosts use to recognize foreign eggs and affect the course of evolution in parasitic egg mimicry.
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Affiliation(s)
- Mikus Abolins-Abols
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, USA.
| | - Daniel Hanley
- Department of Biology and Environmental Sciences, Long Island University - Post, USA
| | - Csaba Moskát
- MTA-ELTE-MTM Ecology Research Group: a joint research group of the Hungarian Academy of Sciences, the Eötvös Loránd University, and the Hungarian Natural History Museum, Budapest, Hungary
| | - Tomáš Grim
- Na Orátě 497, 78361, Hlubočky, Czech Republic
| | - Mark E Hauber
- Department of Evolution, Ecology, and Behavior, School of Integrative Biology, University of Illinois, Urbana-Champaign, USA
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27
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Hanley D, Gern K, Hauber ME, Grim T. Host Responses to Foreign Eggs across the Avian Visual Color Space. Am Nat 2019; 194:17-27. [DOI: 10.1086/703534] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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28
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Cotter SC, Pincheira-Donoso D, Thorogood R. Defences against brood parasites from a social immunity perspective. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180207. [PMID: 30967090 PMCID: PMC6388036 DOI: 10.1098/rstb.2018.0207] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/07/2019] [Indexed: 12/14/2022] Open
Abstract
Parasitic interactions are so ubiquitous that all multicellular organisms have evolved a system of defences to reduce their costs, whether the parasites they encounter are the classic parasites which feed on the individual, or brood parasites which usurp parental care. Many parallels have been drawn between defences deployed against both types of parasite, but typically, while defences against classic parasites have been selected to protect survival, those against brood parasites have been selected to protect the parent's inclusive fitness, suggesting that the selection pressures they impose are fundamentally different. However, there is another class of defences against classic parasites that have specifically been selected to protect an individual's inclusive fitness, known as social immunity. Social immune responses include the anti-parasite defences typically provided for others in kin-structured groups, such as the antifungal secretions produced by termite workers to protect the brood. Defences against brood parasites, therefore, are more closely aligned with social immune responses. Much like social immunity, host defences against brood parasitism are employed by a donor (a parent) for the benefit of one or more recipients (typically kin), and as with social defences against classic parasites, defences have therefore evolved to protect the donor's inclusive fitness, not the survival or ultimately the fitness of individual recipients This can lead to severe conflicts between the different parties, whose interests are not always aligned. Here, we consider defences against brood parasitism in the light of social immunity, at different stages of parasite encounter, addressing where conflicts occur and how they might be resolved. We finish with considering how this approach could help us to address longstanding questions in our understanding of brood parasitism. This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.
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Affiliation(s)
- S. C. Cotter
- School of Life Sciences, University of Lincoln, Brayford Pool, Lincoln, Lincolnshire LN6 7TS, UK
| | - D. Pincheira-Donoso
- Department of Biosciences, Nottingham Trent University, Clifton Campus, Nottingham, Nottinghamshire NG1 8NS, UK
| | - R. Thorogood
- Helsinki Institute of Life Science (HiLIFE), University of Helsinki, Helsinki, Finland
- Research Programme in Organismal and Evolutionary Biology, Faculty of Biological & Environmental Sciences, University of Helsinki, Helsinki, Finland
- Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, UK
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29
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Thorogood R, Spottiswoode CN, Portugal SJ, Gloag R. The coevolutionary biology of brood parasitism: a call for integration. Philos Trans R Soc Lond B Biol Sci 2019; 374:20180190. [PMID: 30967086 PMCID: PMC6388032 DOI: 10.1098/rstb.2018.0190] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2019] [Indexed: 11/12/2022] Open
Abstract
Obligate brood-parasitic cheats have fascinated natural historians since ancient times. Passing on the costs of parental care to others occurs widely in birds, insects and fish, and often exerts selection pressure on hosts that in turn evolve defences. Brood parasites have therefore provided an illuminating system for researching coevolution. Nevertheless, much remains unknown about how ecology and evolutionary history constrain or facilitate brood parasitism, or the mechanisms that shape or respond to selection. In this special issue, we bring together examples from across the animal kingdom to illustrate the diverse ways in which recent research is addressing these gaps. This special issue also considers how research on brood parasitism may benefit from, and in turn inform, related fields such as social evolution and immunity. Here, we argue that progress in our understanding of coevolution would benefit from the increased integration of ideas across taxonomic boundaries and across Tinbergen's Four Questions: mechanism, ontogeny, function and phylogeny of brood parasitism. We also encourage renewed vigour in uncovering the natural history of the majority of the world's brood parasites that remain little-known. Indeed, it seems very likely that some of nature's brood parasites remain entirely unknown, because otherwise we are left with a puzzle: if parental care is so costly, why is brood parasitism not more common? This article is part of the theme issue 'The coevolutionary biology of brood parasitism: from mechanism to pattern'.
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Affiliation(s)
- Rose Thorogood
- Helsinki Institute of Life Science, University of Helsinki, Helsinki 00014, Finland
- Research Program in Organismal and Evolutionary Biology, Faculty of Environmental and Biological Sciences, University of Helsinki, Helsinki 00014, Finland
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Claire N. Spottiswoode
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
- FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Rondebosch 7701, South Africa
| | - Steven J. Portugal
- School of Biological Sciences, Royal Holloway University of London, Egham, Surrey TW20 0EX, UK
| | - Ros Gloag
- School of Life and Environmental Sciences, University of Sydney, Sydney 2006, Australia
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