title: Does migration of hybrids contribute to post-zygotic isolation in flycatchers?
abstract: In the face of hybridization, species integrity can only be maintained through post-zygotic isolating barriers (PIBs). PIBs need not only be intrinsic (i.e. hybrid inviability and sterility caused by developmental incompatibilities), but also can be extrinsic due to the hybrid's intermediate phenotype falling between the parental niches. For example, in migratory species, hybrid fitness might be reduced as a result of intermediate migration pathways and reaching suboptimal wintering grounds. Here, we test this idea by comparing the juvenile to adult survival probabilities as well as the wintering grounds of pied flycatchers (Ficedula hypoleuca), collared flycatchers (Ficedula albicollis) and their hybrids using stable isotope ratios of carbon (delta13C) and nitrogen (delta15N) in feathers developed at the wintering site. Our result supports earlier observations of largely segregated wintering grounds of the two parental species. The isotope signature of hybrids clustered with that of pied flycatchers. We argue that this pattern can explain the high annual survival of hybrid flycatchers. Hence, dominant expression of the traits of one of the parental species in hybrids may substantially reduce the ecological costs of hybridization.
authors.affiliation: Theoretical Biology Group, Centre for Ecological and Evolutionary Studies, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands. t.veen@rug.nl
authors.forename: Thor
authors.initials: T
authors.lastname: Veen
authors.forename: Nina
authors.initials: N
authors.lastname: Svedin
authors.forename: Jukka T
authors.initials: JT
authors.lastname: Forsman
authors.forename: Mårten B
authors.initials: MB
authors.lastname: Hjernquist
authors.forename: Anna
authors.initials: A
authors.lastname: Qvarnström
authors.forename: Katherine A Thuman
authors.initials: KA
authors.lastname: Hjernquist
authors.forename: Johan
authors.initials: J
authors.lastname: Träff
authors.forename: Marcel
authors.initials: M
authors.lastname: Klaassen
mesh_terms: D000349:Africa; D000367:Age Factors; D000704:Analysis of Variance; D025041:Animal Migration; D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D016000:Cluster Analysis; D003710:Demography; D005828:Genetics, Population; D006824:Hybridization, Genetic; D040582:Inheritance Patterns / Q000235:genetics; D009587:Nitrogen Isotopes / Q000032:analysis; D046109:Passeriformes / Q000235:genetics* / Q000502:physiology; D020641:Polymorphism, Single Nucleotide; D012621:Seasons
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes