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Experimental demonstration of a parasite-induced immune response in wild birds: Darwin’s ﬁnches and introduced nest ﬂies.

Por:

Koop, Jennifer A

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ArtículoIdioma: Inglés Tema(s):

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21 598.883 KOO

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En: Ecology and Evolution Vol. 3, no. 8 (May 2013), p. 2514-2523Tema: Ecological immunology aims to explain variation among hosts in the strength and efﬁcacy of immunological defenses. However, a shortcoming has been the failure to link host immune responses to actual parasites under natural conditions. Here, we present one of the ﬁrst experimental demonstrations of a parasiteinduced immune response in a wild bird population. The recently introduced ectoparasitic nest ﬂy Philornis downsi severely impacts the ﬁtness of Darwin’s ﬁnches and other land birds in the Galapagos Islands. An earlier study showed that female medium ground ﬁnches (Geospiza fortis) had P. downsi-binding antibodies correlating with presumed variation in ﬂy exposure over time. In the current study, we experimentally manipulated ﬂy abundance to test whether the ﬂy does, in fact, cause changes in antibody levels. We manipulated P. downsi abundance in nests and quantiﬁed P. downsi-binding antibody levels of médium ground ﬁnch mothers, fathers, and nestlings. We also quantiﬁed host behaviors, such as preening, which can integrate with antibody-mediated defenses against ectoparasites. Philornis downsi-binding antibody levels were signiﬁcantly higher among mothers at parasitized nests, compared to mothers at (fumigated) nonparasitized nests. Mothers with higher antibody levels tended to have fewer parasites in their nests, suggesting that antibodies play a role in defense against parasites. Mothers showed no behavioral changes that would enhance the effectiveness of the immune response. Neither adult males, nor nestlings, had P. downsi-induced immunological or behavioral responses that would enhance defense against ﬂies. None of the parasitized nests ﬂedged any offspring, despite the immune response by mothers. Thus, this study shows that, while the immune response of mothers appeared to be defensive, it was not sufﬁcient to rescue current reproductive ﬁtness. This study further shows the importance of testing the ﬁtness consequences of immune defenses, rather than assuming that such responses increase host ﬁtness.

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Existencias
Imagen de cubierta	Tipo de ítem	Biblioteca actual	Biblioteca de origen	Colección	Ubicación en estantería	Signatura topográfica	Materiales especificados	Info Vol	URL	Copia número	Estado	Notas	Fecha de vencimiento	Código de barras	Reserva de ítems	Prioridad de la cola de reserva de ejemplar	Reservas para cursos
	Artículo	Corley Smith Library Artículos		Galápagos		598.883 KOO (Navegar estantería(Abre debajo))					Disponible			2017-2144
	Documento electrónico	Corley Smith Library Colección PDF		Galápagos		598.883 KOO 2013 (Navegar estantería(Abre debajo))					Disponible			2021-2016

Ecological immunology aims to explain variation among hosts in the strength and efﬁcacy of immunological defenses. However, a shortcoming has been the failure to link host immune responses to actual parasites under natural conditions.
Here, we present one of the ﬁrst experimental demonstrations of a parasiteinduced immune response in a wild bird population. The recently introduced ectoparasitic nest ﬂy Philornis downsi severely impacts the ﬁtness of Darwin’s
ﬁnches and other land birds in the Galapagos Islands. An earlier study showed that female medium ground ﬁnches (Geospiza fortis) had P. downsi-binding antibodies correlating with presumed variation in ﬂy exposure over time. In the current study, we experimentally manipulated ﬂy abundance to test whether the ﬂy does, in fact, cause changes in antibody levels. We manipulated P. downsi abundance in nests and quantiﬁed P. downsi-binding antibody levels of médium ground ﬁnch mothers, fathers, and nestlings. We also quantiﬁed host behaviors, such as preening, which can integrate with antibody-mediated defenses against ectoparasites. Philornis downsi-binding antibody levels were signiﬁcantly higher among mothers at parasitized nests, compared to mothers at (fumigated) nonparasitized nests. Mothers with higher antibody levels tended to have fewer parasites in their nests, suggesting that antibodies play a role in defense against parasites. Mothers showed no behavioral changes that would enhance the effectiveness of the immune response. Neither adult males, nor nestlings, had P. downsi-induced immunological or behavioral responses that would enhance defense against ﬂies. None of the parasitized nests ﬂedged any offspring, despite the immune response by mothers. Thus, this study shows that, while the immune response of mothers appeared to be defensive, it was not sufﬁcient to rescue current reproductive ﬁtness. This study further shows the importance of testing the ﬁtness consequences of immune defenses, rather than assuming that such responses increase host ﬁtness.

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