Species hybridization can lead to fitness costs, species collapse, and novel evolutionary trajectories in changing environments. Hybridization is predicted to be more common when environmental conditions change rapidly. Here, we test patterns of hybridization in three sympatric tree finch species (small tree finch Camarhynchus parvulus, medium tree finch Camarhynchus pauper, and large tree finch: Camarhynchus psittacula) that are currently recognized on Floreana Island, Galápagos Archipelago. Genetic analysis of microsatellite data from contemporary samples showed two genetic populations and one hybrid cluster in both 2005 and 2010; hybrid individuals were derived from genetic population 1 (small morph) and genetic population 2 (large morph). Females of the large and rare species were more likely to pair with males of the small common species. Finch populations differed in morphology in 1852–1906 compared with 2005/2010. An unsupervised clustering method showed (a) support for three morphological clusters in the historical tree finch sample (1852–1906), which is consistent with current species recognition; (b) support for two or three morphological clusters in 2005 with some (19%) hybridization; and (c) support for just two morphological clusters in 2010 with frequent (41%) hybridization. We discuss these findings in relation to species demarcations of Camarhynchus tree finches on Floreana Island.
Allele size data Floreana Tree Finches 2005 & 2010
Allele size data for tree finches on Floreana Island, Galapagos. "Year" refers to whether an individual was sampled in 2005 or 2010. "FTA" is a unique number that was given to the blood sample of each sampled individual (this number was written next to blood samples stored on FTA paper). "Ring number" refers to the identifier inscribed on an aluminum band around a bird's tarsus. "Pop" refers to the species category given to each individual in the field: small tree finch=1, medium tree finch=2, large tree finch=3. Remaining information refers to allele size (maximum height at peak of allele) at each of 10 microsatellite loci (Gf01, Gf03, Gf04, Gf05, Gf06, Gf07, Gf09, Gf11, Gf12, Gf13)
Allele size data Floreana Tree Finches 2005 and 2010 Dryad.xlsx
Genetic Population and Morphology_Floreana Tree Finches 2005 and 2010_Am Nat
Morphological measurements of tree finches sampled on Floreana Island, Galapagos, 2005 and 2010. Techniques for measuring morphological features are described in the associated manuscript. Genetic population refers to population assignment based on analyses of microsatellite loci (using the program STRUCTURE).
Assortative Pairing and Genetic Population_Am Nat
Assortative pairing, genetic and morphological data for male and female tree finches sampled on Floreana Island, Galapagos, 2005 and 2010. Techniques for measuring morphological features are described in the associated manuscript. Genetic population refers to population assignment based on analyses of microsatellite loci (using the program STRUCTURE).
Philornis Intensity and Genetic Population Floreana Tree Finches_Am Nat
Total Philornis downsi larvae intensity per nest for tree finches breeding on Floreana Island in 2005, 2010 and 2012. Genetic population refers to population assignment based on analyses of microsatellite loci (using the program STRUCTURE). Male colour and putative species assignment are also provided (STF=small tree finch, MTF=medium tree finch, LTF= large tree finch).
Philornis Intensity and Genetic Population_Floreana Tree Finches_Am Nat.xlsx