How to Spot a Stranger's Egg? A Mimicry‐Specific Discordancy Effect in the Recognition of Parasitic Eggs

Moskát, Csaba; Zölei, Anikó; Bán, Miklós; Elek, Zoltán; Tong, Lainga; Geltsch, Nikoletta; Hauber, Márk E.

doi:10.1111/eth.12234

Cited by 27 publications

(30 citation statements)

References 62 publications

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“…That the rejection of foreign eggs does not depend on the degree of contrast between eggs and the nest lining (this study) provides support for earlier findings in hosts of egg-mimetic brood parasites that egg rejection is driven mechanistically by differences between foreign and own eggs (Cassey et al, 2008;Stevens et al, 2013;Moskat et al, 2014b). In contrast, cowbird eggs in robin nests are exceptional to this pattern: Croston and Hauber (2014a) showed that while robins' responses to artificial egg colors are generally predicted by chromatic JNDs differentiating foreign versus host eggs, artificial cowbird ground color-mimetic (beige) eggs are rejected in 100% of trials, despite their relatively low avianperceivable chromatic difference from robin eggs (Fig.…”

Section: Discussionsupporting

confidence: 87%

The role of egg-nest contrast in the rejection of brood parasitic eggs

Aidala

Croston

Schwartz

et al. 2015

Journal of Experimental Biology

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Hosts of avian brood parasites can avoid the reproductive costs of raising genetically unrelated offspring by rejecting parasitic eggs. The perceptual cues and controls mediating parasitic egg discrimination and ejection are well studied: hosts are thought to use differences in egg color, brightness, maculation, size and shape to discriminate between their own and foreign eggs. Most theories of brood parasitism implicitly assume that the primary criteria to which hosts attend when discriminating eggs are differences between the eggs themselves. However, this assumption is confounded by the degree to which chromatic and achromatic characteristics of the nest lining co-vary with egg coloration, so that egg-nest contrast per se might be the recognition cue driving parasitic egg detection. Here, we systematically tested whether and how egg-nest contrast itself contributes to foreign egg discrimination. In an artificial parasitism experiment, we independently manipulated egg color and nest lining color of the egg-ejector American robin (Turdus migratorius), a host of the obligate brood parasitic brown-headed cowbird (Molothrus ater). We hypothesized that the degree of contrast between foreign eggs and the nest background would affect host egg rejection behavior. We predicted that experimentally decreasing egg-nest chromatic and achromatic contrast (i.e. rendering parasitic eggs more cryptic against the nest lining) would decrease rejection rates, while increasing egg-nest contrast would increase rejection rates. In contrast to our predictions, egg-nest contrast was not a significant predictor of egg ejection patterns. Instead, egg color significantly predicted responses to parasitism. We conclude that eggegg differences are the primary drivers of egg rejection in this system. Future studies should test for the effects of egg-nest contrast per se in predicting parasitic egg recognition in other host-parasite systems, including those hosts building enclosed nests and those parasites laying cryptic eggs, as an alternative to hypothesized effects of egg-egg contrast.

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Section: Discussionsupporting

confidence: 87%

The role of egg-nest contrast in the rejection of brood parasitic eggs

Aidala

Croston

Schwartz

et al. 2015

Journal of Experimental Biology

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“…In our case, we found that egg rejection by warblers was as high as 78.3% when the warbler eggs were artificially painted with ten extra spots. Although the spots deliberately painted on the egg could not represent the natural spot pattern of the egg, this manipulation is commonly used to test the effect of egg patterns on egg rejection by warbler hosts (Hauber et al 2006;Moskát et al 2008Moskát et al , 2014. Therefore, our study clearly confirms that egg-spot patterns play an important role in egg rejection by the Oriental Reed Warbler, consequently leading to high selection pressure for the cuckoo to evolve a better matching egg-laying strategy.…”

Section: Discussionsupporting

confidence: 57%

“…Several studies have pointed out the significance of the effect of spot pattern on egg recognition by the hosts (Hauber et al 2006;Moskát et al 2008Moskát et al , 2014. Therefore, we also conducted egg recognition experiments to confirm the importance of spot matching in this cuckoowarbler system.…”

Section: Egg Recognition Experimentsmentioning

confidence: 72%

Egg-spot matching in common cuckoo parasitism of the oriental reed warbler: effects of host nest availability and egg rejection

Ruan

Wang

et al. 2016

Avian Res

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Background:The success of cuckoo parasitism is thought to depend largely on the extent of egg matching between cuckoo and host eggs, since poor-matching cuckoo egg would lead to more frequent egg rejection by the host. In this study, we investigated how egg-spot matching between the Common Cuckoo (Cuculus canorus) and its host, the Oriental Reed Warbler (Acrocephalus orientalis) is affected by the local parasitism rate, nest availability in breeding synchronization and egg rejection. Methods:We used the paired design of parasitized and their nearest non-parasitized nests where breeding occurred simultaneously to compare egg-spot matching. The image analysis was used to compare four eggshell pattern variables, namely spot size, density, coverage on the different areas of egg surface, and the distribution on the whole egg surface. Egg recognition experiments were conducted to test the effect of egg spots on egg rejection by the host. Results:Our results show that much better matching in almost all spot parameters tested on the side of the egg and the spot distribution on the whole egg occurred in parasitized nests than in non-parasitized nests. Matching of spot density between cuckoo and host eggs in parasitized nests increased with the synchronization between temporal availability of nests and the egg-laying period of female cuckoos. Egg recognition experiments in which the warbler eggs were deliberately painted with extra spots led to a significantly higher egg rejection rate (78.3%) than of unpainted eggs. Conclusion:Our data suggest that both the high temporal encounter rate between cuckoo and warbler nests as well as the high egg rejection ability of the host are important factors for egg-spot matching of the cuckoos.

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“…Previous research on this host has shown that perceived eggshell coloration is an important cue for warblers’ egg rejection (Moskát et al. ; Hauber et al. ), while in our study population age, host genotype, and ambient light do not affect host egg rejection (Honza et al.…”

Section: Introductioncontrasting

confidence: 42%

Dynamic egg color mimicry

Hanley

Šulc

Hauber

et al. 2016

Ecology and Evolution

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Evolutionary hypotheses regarding the function of eggshell phenotypes, from solar protection through mimicry, have implicitly assumed that eggshell appearance remains static throughout the laying and incubation periods. However, recent research demonstrates that egg coloration changes over relatively short, biologically relevant timescales. Here, we provide the first evidence that such changes impact brood parasite–host eggshell color mimicry during the incubation stage. First, we use long‐term data to establish how rapidly the Acrocephalus arundinaceus Linnaeus (great reed warbler) responded to natural parasitic eggs laid by the Cuculus canorus Linnaeus (common cuckoo). Most hosts rejected parasitic eggs just prior to clutch completion, but the host response period extended well into incubation (~10 days after clutch completion). Using reflectance spectrometry and visual modeling, we demonstrate that eggshell coloration in the great reed warbler and its brood parasite, the common cuckoo, changes rapidly, and the extent of eggshell color mimicry shifts dynamically over the host response period. Specifically, 4 days after being laid, the host should notice achromatic color changes to both cuckoo and warbler eggs, while chromatic color changes would be noticeable after 8 days. Furthermore, we demonstrate that the perceived match between host and cuckoo eggshell color worsened over the incubation period. These findings have important implications for parasite–host coevolution dynamics, because host egg discrimination may be aided by disparate temporal color changes in host and parasite eggs.

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How to Spot a Stranger's Egg? A Mimicry‐Specific Discordancy Effect in the Recognition of Parasitic Eggs

Cited by 27 publications

References 62 publications

The role of egg-nest contrast in the rejection of brood parasitic eggs

The role of egg-nest contrast in the rejection of brood parasitic eggs

Egg-spot matching in common cuckoo parasitism of the oriental reed warbler: effects of host nest availability and egg rejection

Dynamic egg color mimicry

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