Antagonistic antiparasite defenses: nest defense and egg rejection in the magpie host of the great spotted cuckoo |
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Authors: | Soler Juan Jose; Soler Manuel; Perez-Contreras Tomas; Aragon Santiago; Moller Anders Pape |
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Institution: | a
Departamento de Biología Animal y
Ecología, Facultad de Ciencias, Universidad de
Granada, E-18071 Granada, Spain
b
Ecole Normale Supérieure, Departement de
Biologie, Laboratoire Signaux et Régulations
Endocrines, CNRS EP 119, 46, rue d'Ulm, F-75252 Paris Cedex 05, France
c
Laboratoire d'Ecologie, CNRS URA 258,
Université Pierre et Marie Curie, 7 quai St.
Bernard, Case 237, F-75252 Paris Cedex 05, France |
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Abstract: | Brood parasites dramatically reduce the reproductive successof their
hosts, which therefore have developed defenses againstbrood parasites. The
first line of defense is protecting thenest against adult parasites. When the
parasite has successfullyparasitized a host nest, some hosts are able to
recognize andreject the eggs of the brood parasite, which constitutes the
secondline of defense. Both defense tactics are costly and would be
counteractedby brood parasites. While a failure in nest defense implies
successfulparasitism and therefore great reduction of reproductive successof
hosts, a host that recognizes parasitic eggs has the opportunityto reduce the
effect of parasitism by removing the parasiticegg. We hypothesized that, when
nest defense is counteractedby the brood parasite, hosts that recognize
cuckoo eggs shoulddefend their nests at a lower level than nonrecognizers
becausethe former also recognize adult cuckoos. Magpie (Pica pica)
hoststhat rejected model eggs of the brood parasitic great spottedcuckoo
(Clamator glandarius) showed lower levels of nest defensewhen
exposed to a great spotted cuckoo than when exposed toa nest predator (a
carrion crow Corvus corone). Moreover, magpiesrejecting cuckoo eggs
showed lower levels of nest defense againstgreat spotted cuckoos than
nonrecognizer magpies, whereas differencesin levels of defense disappeared
when exposed to a carrion crow.These results suggest that hosts specialize in
antiparasitedefense and that different kinds of defense are antagonistically
expressed.We suggest that nest-defense mechanisms are ancestral, whereasegg
recognition and rejection is a subsequent stage in the coevolutionaryprocess.
However, host recognition ability will not be expressedwhen brood parasites
break this second line of defense. |
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Keywords: | brood parasitism Clamator glandarius coevolution hierarchical defense strategies host defense strategies great spotted cuckoos magpies Pica pica |
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