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dc.contributor.authorDaCosta, Jeffreyen_US
dc.date.accessioned2016-03-31T19:15:50Z
dc.date.available2016-03-31T19:15:50Z
dc.date.issued2014
dc.identifier.urihttps://hdl.handle.net/2144/15392
dc.description.abstractThe African indigobirds (Vidua spp.) are exceptional among avian brood parasites in that mimicry of host vocalizations plays an integral role in their social behaviors and evolutionary history. Young indigobirds imprint on the vocalizations of their hosts during development, adult males include mimicry of these vocalizations in their own repertoire, and adult females use these songs to choose both their mates and the nests they parasitize. Imprinting on the host during development therefore results in assortative mating and host fidelity, but also provides a mechanism for rapid, sympatric speciation via host shift. Host shifts require some degree of host infidelity, however, and the same behavioral mechanisms may thus lead to hybridization if eggs are laid in the nest of a host species already "occupied" by another indigobird species. Thus, it is not clear if the morphological and genetic similarity of most indigobird species is due to recent common ancestry or ongoing hybridization. I addressed this uncertainty by studying indigobirds in East Africa, a region that was colonized by West African ancestors in the late Pleistocene and is currently home to four indigobird species. I analyzed variation among species in: vi1) the responses of territorial males to playbacks of conspecific and heterospecific vocalizations; 2) temporal and frequency traits of chatter calls and complex non-mimicry songs; 3) morphological characters; and 4) genomic polymorphisms. The playback experiment shows that host mimicry is an important cue in species recognition, and suggests that it may contribute to species cohesion when juveniles or adults disperse beyond the boundaries of their dialect neighborhood. Analyses of both non-mimetic vocalizations and morphological characters (i.e., plumage color and body size) reveal that they are shaped by divergence among species as well as local ecology. Analyses of thousands of "double-digest" restriction site-associated DNA (ddRAD) loci scattered across the genome indicate that both species identity and geographic divergence contribute to population structure. Taken together, the results show that the tempo of speciation and morphological divergence among indigobirds associated with different hosts is likely variable, depending on geographic context, and the breeding ecology and morphology of alternative hosts.en_US
dc.language.isoen_US
dc.subjectZoologyen_US
dc.titleBehavioral, morphological, and genomic analyses of population structure in brood parasitic indigobirds (Vidua spp.)en_US
dc.typeThesis/Dissertationen_US
dc.date.updated2016-03-12T07:12:37Z
etd.degree.nameDoctor of Philosophyen_US
etd.degree.leveldoctoralen_US
etd.degree.disciplineBiologyen_US
etd.degree.grantorBoston Universityen_US


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