Genomic signatures of isolation, hybridization, and selection during speciation of island finches

Data associated to the study Genomic signatures of isolation, hybridization, and selection during speciation of island finches

Contents

• Table_S9_samples_accession_nos.xlsx: Editable Excel matrix with sample names and accession numbers.
• RAD_SNPs_stacks_42424_loci.vcf.tar.gz: VCF file (gzip-compressed tarball) containing SNPs in 42,424 loci, based on analyses of restriction site-associated DNA (RAD) sequencing using Stacks.
• RAD_SNPs_standard_variant_calling.vcf.tar.gz: VCF file (gzip-compressed tarball) containing 131,661 SNPs from standard variant calling pipelines.
• mitochondrial_markers_full_data.nex: Nexus file containing mitochondrial (mt) sequences used for mt-phylogeny. Partitioned for COX2, tRNA-Lys, ATP8, and ATP6. 
• sequences_nuclear_genotype_with_zebra_finch_TG.tar.gz: Directory (gzip-compressed tarball) containing genotype sequence (heterozygous sites with IUPAC codes) alignments of nuclear markers in nexus files. In addition to the study species, the sequence for zebra finch Taeniopygia guttata is included with sample code TG.
• sequences_nuclear_phased_and_mitochondrial_haplotypes_matching.tar.gz: Directory (gzip-compressed tarball) containing phased sequence (haplotype) alignments of nuclear markers in nexus files. These include only those individuals that match individuals sequenced for mitochondrial markers (also included here). In case of recombining loci, both the full locus and the largest non-recombining block are represented.
• sequences_nuclear_phased_haplotypes_all.tar.gz: Directory (gzip-compressed tarball) containing phased sequence (haplotype) alignments of nuclear markers in nexus files. These include all individuals. In case of recombining loci, both the full locus and the largest non-recombining block are represented.
• microsatellite_dataset.xlsx: Microsatellite datasets for the study species and additional outgroups.

  Sequences and short read datasets available from NCBI; accession numbers in Table S9 (Table_S9_samples_accession_nos.xlsx).

Study summary

Sister species occurring sympatrically on islands are rare and offer unique opportunities to understand how speciation can proceed in the face of gene flow. The São Tomé grosbeak is a massive-billed, ‘giant’ finch endemic to the island of São Tomé in the Gulf of Guinea, where it has diverged from its co-occurring sister species the Príncipe seedeater, an average-sized finch that also inhabits two neighbouring islands. Here, we show that the grosbeak carries a large number of unique alleles different from all three Príncipe seedeater populations, but also shares many alleles with the sympatric São Tomé population of the seedeater, a genomic signature signifying divergence in isolation as well as subsequent introgressive hybridization. Furthermore, genomic segments that remain unique to the grosbeak are situated close to genes, including genes that determine bill morphology, suggesting the preservation of adaptive variation through natural selection during divergence with gene flow. This study reveals a complex speciation process whereby genetic drift, introgression, and selection during periods of isolation and secondary contact all have shaped the diverging genomes of these sympatric island endemic finches.