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

作者：Nietli**ach Pirmin^*; Wandeler Peter; Parker Patricia G; Grant Peter R; Grant B Rosemary; Keller Lukas F; Hoeck Paquita E A

来源：Molecular Phylogenetics and Evolution, 2013, 69(3): 581-592.

DOI：10.1016/j.ympev.2013.07.020

• Introgression
• Hybridization
• Phylogeny
• Speciation
• Mimus
• Nesomimus

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 Galapagos 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 Cristobal (M. melanotis) and Espanola (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 other M. parvulus populations. This pattern shows that Genovesa mockingbirds contain mitochondria and some autosomal alleles that have most likely introgressed from M. melanotis into a largely M. parvulus background, making Genovesa mockingbirds a lineage of mixed ancestry, possibly undergoing speciation. Consistent with this hypothesis, mockingbirds on Genovesa are more clearly differentiated morphologically from other M. parvulus populations than M. melanotis is from M. parvulus.

• 出版日期2013-12