Data from: Hybridization fluctuates with rainfall in Darwin's tree finches

Hybridization in natural populations may be an adaptive response to shifting climatic regimes, but understanding this can be limited by temporal sampling effort and confident hybrid identification. On the Galapagos Islands, Darwin's finches regularly hybridize, and the islands show extreme annual variation in rainfall, however the effect of annual rainfall on the frequency of finch hybridization is little known. Across a 19-year period on Floreana Island, we compare patterns of hybridization in sympatric Darwin's tree finches (N = 425; Camaryhnchus spp.) and test for an effect of annual rainfall on, 1) the frequency of hybrids (C. pauper × C. parvulus), and 2) the percentage of male hybrid birds produced per year (hybrid recruitment). Annual rainfall correlated with recruitment positively for hybrids, negatively for C. parvulus and not at all for C. pauper. Furthermore, the percentage of hybrids (range: 12-56%) and C. parvulus did not change with sampling year, but the critically endangered C. pauper declined. Our findings indicate that hybrid recruitment is recurring and variable according to annual rainfall in Camarhynchus Darwin's finches.The dataset contains two files: 1) Genetic data (microsatellite data) for 9 loci - with individual IDs and initial assignment to each parental cluster prior to assessment of admixture and hybridisation via STRUCTURE analysis. 2) Data for male age and birth year and rainfall data per year with individuals genetically assigned to either the parental or hybrid groups. Funding provided by: Australian Research CouncilCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000923Award Number: Funding provided by: Rufford FoundationCrossref Funder Registry ID: http://dx.doi.org/10.13039/100007463Award Number: Funding provided by: Mohamed bin Zayed Species Conservation FundCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100011672Award Number: Funding provided by: Max Planck Institute for Ornithology*Crossref Funder Registry ID: Award Number: Funding provided by: Royal Society for the Protection of Birds/Birdfair*Crossref Funder Registry ID: Award Number: Funding provided by: Earthwatch InstituteCrossref Funder Registry ID: http://dx.doi.org/10.13039/100001089Award Number: Funding provided by: Galapagos Conservation FundCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100016404Award Number: Funding provided by: Australian Federation of University Women – South AustraliaCrossref Funder Registry ID: http://dx.doi.org/10.13039/501100000993Award Number: Funding provided by: Max Planck Institute for OrnithologyCrossref Funder Registry ID: Funding provided by: Royal Society for the Protection of Birds/BirdfairCrossref Funder Registry ID:Our study was conducted in the highlands of Floreana Island, Galápagos Archipelago during February and in some cases March/April during 1997, 2005, 2006, 2010, 2012, 2013, 2014, and 2016 (8 years of sampling spanning 19 years). The focal tree finch species were small tree finch (Camarhynchus parvulus), medium tree finch (C. pauper), and the recently discovered hybrid group that arises from pairings between C. pauper females and C. parvulus males. DNA was extracted and genotyped using nine microsatellite loci designed for Darwin's medium ground finch (Geospiza fortis: GF01, GF03, GF04, GF05, GF06, GF07, GF11, GF12, GF13, Petren, 1998), with protocols described in Kleindorfer et al. (2014) and Peters et al. (2017). Analyses are as described in the corresponding paper with this data