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Hybrid ancestry of an island subspecies of Galápagos mockingbird explains discordant gene trees


Nietlisbach, Pirmin; Wandeler, Peter; Parker, Patricia G; Grant, Peter R; Grant, Rosemary B; Keller, Lukas F; Hoeck, Paquita E A (2013). Hybrid ancestry of an island subspecies of Galápagos mockingbird explains discordant gene trees. Molecular Phylogenetics and Evolution, 69:581-592.

Abstract

Introgression of genes through hybridization has been proposed to be an important driver of speciation, but in animals this has been shown only in relatively few cases until recently. Additionally, introgressive hybridization among non-sister species leads to a change in the gene tree topology of the concerned loci and thus complicates phylogenetic reconstruction. However, such cases of ancient introgression have been very difficult to demonstrate in birds. Here, we present such an example in an island bird subspecies, the Genovesa mockingbird (Mimus parvulus bauri). We assessed phylogenetic relationships and population structure among mockingbirds of the Galápagos archipelago using mitochondrial and nuclear DNA sequences, autosomal microsatellites, and morphological measurements. Mitochondrial haplotypes of Genovesa mockingbirds clustered closely with the haplotypes from two different species, San Cristóbal (M. melanotis) and Española (M. macdonaldi) mockingbirds. The same pattern was found for some haplotypes of two nuclear gene introns, while the majority of nuclear haplotypes of Genovesa mockingbirds were shared with other populations of the same species (M. parvulus). At 26 autosomal microsatellites, Genovesa mockingbirds grouped with otherM. parvuluspopulations. This pattern shows that Genovesa mockingbirds contain mitochondria and some autosomal alleles that have most likely introgressed from M. melanotisinto a largely M. parvulusbackground, making Genovesa mockingbirds a lineage of mixed ancestry, possibly undergoing speciation. Consistent with this hypothesis, mockingbirds on Genovesa are more clearly differentiated morphologically from otherM. parvuluspopulations thanM. melanotis is from M. parvulus.

Abstract

Introgression of genes through hybridization has been proposed to be an important driver of speciation, but in animals this has been shown only in relatively few cases until recently. Additionally, introgressive hybridization among non-sister species leads to a change in the gene tree topology of the concerned loci and thus complicates phylogenetic reconstruction. However, such cases of ancient introgression have been very difficult to demonstrate in birds. Here, we present such an example in an island bird subspecies, the Genovesa mockingbird (Mimus parvulus bauri). We assessed phylogenetic relationships and population structure among mockingbirds of the Galápagos archipelago using mitochondrial and nuclear DNA sequences, autosomal microsatellites, and morphological measurements. Mitochondrial haplotypes of Genovesa mockingbirds clustered closely with the haplotypes from two different species, San Cristóbal (M. melanotis) and Española (M. macdonaldi) mockingbirds. The same pattern was found for some haplotypes of two nuclear gene introns, while the majority of nuclear haplotypes of Genovesa mockingbirds were shared with other populations of the same species (M. parvulus). At 26 autosomal microsatellites, Genovesa mockingbirds grouped with otherM. parvuluspopulations. This pattern shows that Genovesa mockingbirds contain mitochondria and some autosomal alleles that have most likely introgressed from M. melanotisinto a largely M. parvulusbackground, making Genovesa mockingbirds a lineage of mixed ancestry, possibly undergoing speciation. Consistent with this hypothesis, mockingbirds on Genovesa are more clearly differentiated morphologically from otherM. parvuluspopulations thanM. melanotis is from M. parvulus.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Evolutionary Biology and Environmental Studies
Dewey Decimal Classification:570 Life sciences; biology
590 Animals (Zoology)
Language:English
Date:2013
Deposited On:29 Nov 2013 15:22
Last Modified:08 Dec 2017 00:11
Publisher:Elsevier
ISSN:1055-7903
Publisher DOI:https://doi.org/10.1016/j.ympev.2013.07.020

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