DOI: 10.5061/dryad.mc534
title: Data from: Females drive asymmetrical introgression from rare to common species in Darwin's tree finches

description: The consequences of hybridization for biodiversity depend on the specific
 ecological and evolutionary context in which it occurs. Understanding
 patterns of gene flow among hybridizing species is crucial for determining
 the evolutionary trajectories of species assemblages. The recently
 discovered hybridization between two species of Darwin's tree finches
 (Camarhynchus parvulus and C. pauper) on Floreana Island, Galápagos,
 presents an exciting opportunity to investigate the mechanisms causing
 hybridization and its potential evolutionary consequences under conditions
 of recent habitat disturbance and the introduction of invasive pathogens.
 In this study, we combine morphological and genetic analysis with pairing
 observations to explore the extent, direction and drivers of hybridization
 and to test if hybridization patterns are a result of asymmetrical pairing
 preference driven by females of the rarer species (C. pauper). We found
 asymmetrical introgression from the critically endangered, larger-bodied
 C. pauper to the common, smaller-bodied C. parvulus, which was associated
 with a lack of selection against heterospecific males by C. pauper
 females. Examination of pairing data showed that C. parvulus females
 paired assortatively while C. pauper females showed no such pattern. This
 study shows how sex-specific drivers can determine the direction of gene
 flow in hybridizing species. Furthermore, our results suggest the
 existence of a hybrid swarm comprised of C. parvulus and hybrid birds. We
 discuss the influence of interspecific abundance differences and
 susceptibility to the invasive parasite Philornis downsi on the observed
 hybridisation and recommend that the conservation of this iconic species
 group should be managed jointly rather than species-specific.
description: Peters et al.
 GenotypeDataAllele size data for
 tree finches on Floreana Island, Galapagos "Ring#" refers to the
 identifier inscribed on an aluminum band around a bird's tarsus.
 ‘Cluster’ refers to population assignment based on analyses of
 microsatellite loci using the program STRUCTURE (C. parvulus, Hybrid, C.
 pauper). Remaining information refers to allele size (maximum height at
 peak of allele) at each of nine microsatellite loci (Gf01, Gf03, Gf04,
 Gf05, Gf06, Gf07, Gf11, Gf12, Gf13)Peters et al.
 MorphologyDataMorphological
 measurements of tree finches sampled on Floreana Island, Galápagos in
 2004, 2005, 2006, 2008, 2010, 2012, 2013 and 2014. Techniques for
 measuring morphological variables are described in the associated
 manuscript. ‘Putative population’ refers to assignment based on morphology
 for exploratory analyses (see associated manuscript and supplementary
 material). ‘Cluster’ and ‘Membership Coefficient’ refers to population
 assignment based on analyses of microsatellite loci (using the program
 STRUCTURE).Peters et al.
 PairingDataAssortative pairing,
 genetic and morphological data for male and female tree finches sampled on
 Floreana Island, Galapagos, 2005, 2010, 2012, 2014 and 2014. Techniques
 for measuring morphological features are described in the associated
 manuscript. ‘Cluster’, ‘Cluster_2’ and ‘Membership Coefficient’ refers to
 population assignment based on analyses of microsatellite loci (using the
 program STRUCTURE).