Parasitic cowbirds may defeat host defense by causing rejecters to misimprint on cowbird eggs

Strausberger, Bill M.; Rothstein, Stephen I.

doi:10.1093/beheco/arp042

Cited by 38 publications

(36 citation statements)

References 63 publications

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“…Our second hypothesis tested the importance of observational inspection of hosts' eggs during egg laying in egg discrimination by the great reed warbler, by exposing hosts to false learning of the parasitic eggs (Strausberger and Rothstein, 2009). We found consistently similar results in the 'without learning' and 'with learning' variants of the 'all spotted eggs except one' treatment as Data are number of nests (N).…”

Section: Discussionmentioning

confidence: 62%

Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites

Moskát

Bán

Székely

et al. 2010

Journal of Experimental Biology

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SUMMARYMany avian hosts have evolved antiparasite defence mechanisms, including egg rejection, to reduce the costs of brood parasitism. The two main alternative cognitive mechanisms of egg discrimination are thought to be based on the perceived discordancy of eggs in a clutch or the use of recognition templates by hosts. Our experiments reveal that the great reed warbler (Acrocephalus arundinaceus), a host of the common cuckoo (Cuculus canorus), relies on both mechanisms. In support of the discordancy mechanism, hosts rejected their own eggs (13%) and manipulated ('parasitic') eggs (27%) above control levels in experiments when manipulated eggs were in the majority but when clutches also included a minority of own eggs. Hosts that had the chance to observe the manipulated eggs daily just after laying did not show stronger rejection of manipulated eggs than when the eggs were manipulated at clutch completion. When clutches contained only manipulated eggs, in 33% of the nests hosts showed rejection, also supporting a mechanism of template-based egg discrimination. Rejection using a recognition template might be more advantageous because discordancy-based egg discrimination is increasingly error prone with higher rates of multiple parasitism.

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Section: Discussionmentioning

confidence: 62%

Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites

Moskát

Bán

Székely

et al. 2010

Journal of Experimental Biology

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“…8,9,[11][12][13][14] Learning is an important component of host defenses such as egg recognition, 2,15,16 , and theory suggests that it could be fundamental to the presence or absence of chick recognition in some taxa as well. 10,17 One prominent theory 10 shows that if chick recognition were learned, as it is with eggs, 2,15,16 then the evolution of parasitic chick recognition in hosts of common cuckoos, Cuculus canorus, could be constrained simply by the costs of errors in learning. Shortly after hatching, cuckoo chicks evict all host eggs and chicks, 7 and hosts are assumed to learn the features of their own eggs and chicks in their first breeding attempt.…”

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confidence: 99%

“…21 We tested the hypothesis that coots use the first chicks that hatch in the brood as referents for recognition, following an idea suggested decades ago for egg recognition 15,23,24 and recently supported empirically for eggs. 16 Coots lay large clutches (average 9.0 eggs) that hatch very asynchronously (three to ten days for the complete clutch to hatch). At most parasitized nests, the three chicks that typically hatch on the first hatching day are all host chicks (see later).…”

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confidence: 99%

Coots use hatch order to learn to recognize and reject conspecific brood parasitic chicks

Shizuka

Lyon

2009

Nature

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Avian brood parasites and their hosts provide model systems for investigating links between recognition, learning, and their fitness consequences. [1][2][3][4] One major evolutionary puzzle has continued to capture the attention of naturalists for centuries: why do hosts of brood parasites generally fail to recognize parasitic offspring after they have hatched from the egg, 5-9 even when the host and parasitic chicks differ to almost comic degrees? 7 One prominent theory to explain this pattern proposes that the costs of mistakenly learning to recognize the wrong offspring make recognition maladaptive. 10 Here we show that American coots, Fulica americana, can recognize and reject parasitic chicks in their brood by using learned cues, despite the fact that the hosts and the brood parasites are of the same species. A series of chick cross-fostering experiments confirm that coots use first-hatched chicks in a brood as referents to learn to recognize their own chicks and then discriminate against later-hatched parasitic chicks in the same brood. When experimentally provided with the wrong reference chicks, coots can be induced to discriminate against their own offspring, confirming that the learning errors proposed by theory can exist. 10 However, learning based on hatching order is reliable in naturally parasitized coot nests because host eggs hatch predictably ahead of parasite eggs. Conversely, a lack of reliable information may help to explain why the evolution of chick recognition is not more common in hosts of most interspecific brood parasites.The puzzling absence of chick recognition as a host defense against avian brood parasites has fuelled a long-standing and unresolved debate over what constrains the evolution of such a seemingly obvious host adaptation, producing many alternative hypotheses. 8, 9,[11][12][13][14] Learning is an important component of host defenses such as egg recognition, 2,15,16 , and theory suggests that it could be fundamental to the presence or absence of chick recognition in some taxa as well. 10,17 One prominent theory 10 shows that if chick recognition were learned, as it is with eggs, 2,15,16 then the evolution of parasitic chick recognition in hosts of common cuckoos, Cuculus canorus, could be constrained simply by the costs of errors in learning. Shortly after hatching, cuckoo chicks evict all host eggs and chicks, 7 and hosts are assumed to learn the features of their own eggs and chicks in their first breeding attempt. 2,15 According to the theory, a host parasitized during its first breeding attempt would falsely imprint on the lone parasite as its own chick, and thereafter reject its own offspring for the rest of its life. The extreme fitness costs of such misimprinting 10 could potentially explain why so many cuckoo hosts, and perhaps the hosts of other parasitic species, 17 do not recognize parasitic chicks. Because this misimprinting hypothesis was proposed to explain the absence of adaptation, it cannot be tested directly, but two corollary predictions are tes...

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“…With the assumption that egg patterns are learned the first time a bird breeds, any birds parasitized in their first breeding attempt are predicted to imprint on both their own eggs and the brood parasite's and, consequently, become lifelong acceptors (Lotem et al, 1992;Strausberger and Rothstein, 2009). This predicts that the ratio of acceptors is roughly proportional to the parasitism frequency of first-time breeders.…”

Section: Discussionmentioning

confidence: 99%

Interspecific egg rejection as ecological collateral damage from selection driven by conspecific brood parasitism

2015

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Parasitic cowbirds may defeat host defense by causing rejecters to misimprint on cowbird eggs

Cited by 38 publications

References 63 publications

Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites

Discordancy or template-based recognition? Dissecting the cognitive basis of the rejection of foreign eggs in hosts of avian brood parasites

Coots use hatch order to learn to recognize and reject conspecific brood parasitic chicks

Interspecific egg rejection as ecological collateral damage from selection driven by conspecific brood parasitism

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